# Patent

## Title
Multi-beam active phased array architecture with independent polarization control

## Abstract

In an exemplary embodiment, a phased array antenna comprises multiple subcircuits in communication with multiple radiating elements. The radio frequency signals are independently adjusted for both polarization control and beam steering. In a receive embodiment, multiple RF signals of various polarizations are received and combined into at least one receive beam output. In a transmit embodiment, at least one transmit beam input is divided and transmitted through multiple radiating elements, with the transmitted beams having various polarizations. In an exemplary embodiment, the phased array antenna provides multi-beam formation over multiple operating frequency bands. The wideband nature of the active components allows for operation over multiple frequency bands simultaneously.

## Background
CROSS REFERENCE TO RELATED APPLICATIONS
This application is a continuation of U.S. application Ser. No. 14/617,630, entitled MULTI-BEAM ACTIVE PHASED ARRAY ARCHITECTURE WITH INDEPENDENT POLARIZATION CONTROL,” which was filed on Feb. 9, 2015. The '630 application is a continuation of U.S. application Ser. No. 14/216,760, entitled MULTI-BEAM ACTIVE PHASED ARRAY ARCHITECTURE WITH INDEPENDENT POLARIZATION CONTROL,” which was filed on Mar. 17, 2014. The '760 application is a continuation of U.S. application Ser. No. 13/692,683, entitled “MULTI-BEAM ACTIVE PHASED ARRAY ARCHITECTURE WITH INDEPENDENT POLARIZATION CONTROL,” which was filed on Dec. 3, 2012. The '683 application is a continuation-in-part of U.S. application Ser. No. 13/412,901, entitled “MULTI-BEAM ACTIVE PHASED ARRAY ARCHITECTURE,” which was filed on Mar. 6, 2012. The '901 application is a continuation application of U.S. application Ser. No. 12/759,059, entitled “MULTI-BEAM ACTIVE PHASED ARRAY ARCHITECTURE,” which was filed on Apr. 13, 2010, which is a non-provisional of U.S. Provisional Application No. 61/237,967, entitled “ACTIVE BUTLER AND BLASS MATRICES,” which was filed on Aug. 28, 2009. The '059 application is also a non-provisional of U.S. Provisional Application No. 61/259,375, entitled “ACTIVE HYBRIDS FOR ANTENNA SYSTEMS,” which was filed on Nov. 9, 2009. The '059 application is also a non-provisional of U.S. Provisional Application No. 61/234,513, entitled “ACTIVE FEED FORWARD AMPLIFIER,” which was filed on Aug. 17, 2009. The '059 application is also a non-provisional of U.S. Provisional Application No. 61/222,354, entitled “ACTIVE PHASED ARRAY ARCHITECTURE,” which was filed on Jul. 1, 2009. The '059 application is also a non-provisional of U.S. Provisional Application No. 61/168,913, entitled “ACTIVE COMPONENT PHASED ARRAY ANTENNA,” which was filed on Apr. 13, 2009. The '059 application is also a non-provisional of U.S. Provisional Application No. 61/259,049, entitled “DYNAMIC REAL-TIME POLARIZATION FOR ANTENNAS,” which was filed on Nov. 6, 2009. The '059 application is also a non-provisional of U.S. Provisional Application No. 61/234,521, entitled “MULTI-BAND MULTI-BEAM PHASED ARRAY ARCHITECTURE,” which was filed on Aug. 17, 2009. The '059 application is also a non-provisional of U.S. Provisional Application No. 61/265,605, entitled “HALF-DUPLEX PHASED ARRAY ANTENNA SYSTEM,” which was filed on Dec. 1, 2009. The '059 application is also a non-provisional of U.S. Provisional Application No. 61/222,363, entitled “BIDIRECTIONAL ANTENNA POLARIZER,” which was filed on Jul. 1, 2009. All of the contents of the previously identified applications are hereby incorporated by reference for any purpose in their entirety.


BACKGROUND
A phased array antenna uses multiple radiating elements to transmit, receive, or transmit and receive radio frequency (RF) signals. Phased array antennas are used in various capacities, including communications on the move (COTM) antennas, satellite communication (SATCOM) airborne terminals, SATCOM mobile communications, and SATCOM earth terminals. The application of mobile terminals typically requires the use of automatic tracking antennas that are able to track the beam in azimuth, elevation, and polarization to follow the satellite position while the vehicle is in motion. Moreover, the antenna should be “low-profile,” small and lightweight, thereby fulfilling the stringent aerodynamic and mass constraints encountered in the typical mounting.
One well known type of phased array antenna is an electronically steerable phased array antenna. The electronically steerable phased array antenna has full electronic steering capability and is more compact and lower profile than a comparable mechanical phased array antenna. The main drawback of fully electronic steering is that the antenna usually requires the integration of a lot of expensive analog RF electronic components which may prohibitively raise the cost for commercial applications. A typical electronically steerable phased array antenna comprises an assembly of phase shifters, power splitters, power combiners, and quadrature hybrids. Additionally, a typical electronically steerable phased array requires at least a few of these components at every element in the phased array, which increases the cost and complexity of the architecture.
In a typical prior art embodiment and with reference to FIG. 1, a phased array antenna 100 comprises a radiating element 101 that communicates dual linear signals to a hybrid coupler 102 (either 90° or 180°) and then through low noise amplifiers 103, 104. Furthermore, the dual orthogonal signals are individually phase adjusted by phase shifters 105, 106 before passing through a power combiner 107. In addition, the typical components in a phased array antenna are distributed components that are frequency sensitive and designed for specific frequency bands.
Phase shifters are used in a phased array antenna in order to steer the beam of the signals by controlling the respective phases of the RF signals communicated through the phase shifters. A typical digital phase shifter uses switched delay lines, is physically large, and operates over a narrow band of frequencies due to its distributed nature. Another typical digital phase shifter implements a switched high-pass low-pass filter architecture which has better operating bandwidth compared to a switched delay line but is still physically large.
Also, the phase shifter is often made on gallium arsenide (GaAs). Though other materials may be used, GaAs is a higher quality material designed and controlled to provide good performance of electronic devices. However, in addition to being a higher quality material than the other possible materials, GaAs is also more expensive and more difficult to manufacture. The typical phased array components take up a lot of area on the GaAs, and result in higher costs. Furthermore, a standard phase shifter has high RF loss, which is typically about n+1 dB of loss, where n is the number of phase bits in the phase shifter. Another prior art embodiment uses RF MEMS switches and has lower loss but still consumes similar space and is generally incompatible with monolithic solutions.
Quadrature hybrids or other differential phase generating hybrids are used in a variety of RF applications. In an exemplary embodiment, quadrature hybrids are used for generating circular polarization signals, power combining, or power splitting. In an exemplary embodiment, the outputs of a quadrature hybrid have equal amplitude and a nominally 90° phase difference. In another typical embodiment, the quadrature hybrid is implemented as a distributed structure, such as a Lange coupler, a branchline coupler, and/or the like. A 180° hybrid, such as a magic tee or a ring hybrid, results in a nominally 180° phase shift. In general, quadrature hybrids and 180° hybrids are limited in frequency band and require significant physical space. Additionally, since the structures are distributed in nature, their physical size increases with decreasing frequency. Moreover, the quadrature hybrids and 180° hybrids are typically made of GaAs and have associated RF power loss on the order of 3-4 dB per hybrid when used as a power splitter, and an associated power loss of about 1 dB when used as a power combiner.
In-phase power combiners and in-phase power splitters are also used in a variety of RF applications. In an exemplary embodiment, the outputs of an in-phase hybrid have equal amplitude and a substantially zero differential phase difference. In another exemplary embodiment, the inputs of an in-phase hybrid configured as a power combiner encounter substantially zero differential phase and amplitude shift. In a prior art embodiment, the in-phase hybrid is implemented as a distributed structure such as a Wilkinson coupler. In general, an in-phase hybrid is limited in frequency band and requires significant physical space. Additionally, since the structure is distributed in nature, the physical size increases with decreasing frequency. The in-phase hybrid is typically made of GaAs. Moreover, the in-phase hybrid generally has associated RF power loss on the order of 3-4 dB per hybrid when used as a power splitter and an associated RF power loss of about 1 dB when used as a power combiner.
In addition to the different components in a phased array antenna, an antenna signal can have different polarizations, namely linear, elliptical, or circular. Linear polarization consists of vertical polarization and horizontal polarization, whereas circular polarization consists of left-hand circular polarization (LHCP) and right-hand circular polarization (RHCP). Elliptical polarization is similar to circular polarization but occurs with different values for the vertical and horizontal component magnitudes or if the phase difference between the vertical and horizontal components is a value other than 90°.
Conventional antennas utilize a fixed polarization that is hardware dependent. The basis polarization is generally set during installation of the satellite terminal, at which point the manual configuration of the polarizer hardware is fixed. For example, a polarizer is generally set for LHCP or RHCP and fastened into position. To change polarization would require unfastening the polarizer, rotating it 90° to the opposite circular polarization, and then refastening the polarizer. Clearly this could not be done with much frequency and only a limited number (on the order of 10 or maybe 20) of transceivers could be switched per technician in a given day.
Unlike a typical prior art single polarization antenna, some devices are configured to change polarizations without disassembling the antenna terminal. As an example and with reference to FIG. 2, a prior embodiment is the use of “baseball” switches to provide electronically commandable switching between polarizations. As can be understood by the block diagram, the rotation of the “baseball” switches causes a change in polarization by connecting one signal path to a waveguide while terminating the other signal path. However, each “baseball” switch is physically large and requires a separate rotational actuator with independent control circuitry, which increases the cost of the device such that this configuration is typically not used in consumer broadband terminals.
Furthermore, another approach is to have a system with duplicate transmit and receive hardware for each polarization. The polarization selection is achieved by maintaining the path of the desired signal and deselecting the undesired signal. However, doubling the hardware greatly increases the cost of the terminal. In yet another embodiment, a system may implement solid state diode or FET-based switches. The use of these electronic components may lead to high loss and limited power handling in microwave and mm-wave applications. These alternatives are size, power, and cost prohibitive for most applications, including phased arrays and low cost commercial applications.
Additionally, typical phased array antennas only form a single beam at a time and are often not capable of switching polarization. In order to form additional beams and/or have polarization switching ability from the same radiating aperture, additional phase shifting and power splitting or combining components are required at every radiating element. These additional components are typically distributed in nature, require significant physical space, are lossy, and only operate over relatively narrow frequency bands. For these reasons, polarization agile, multiple beam phased array antennas that can operate over multiple frequency bands are difficult to realize in practice.
Thus, a need exists for a phased array antenna architecture that is not frequency limited or polarization specific, and that is reconfigurable for different polarizations and able to transmit and/or receive over multiple frequencies and form multiple beams. Furthermore, the antenna architecture should be able to be manufactured on a variety of materials and with no associated RF loss. Also, a need exists for a phased array antenna that uses less space than a similar capability prior art architecture, is suitable for a monolithic implementation, and has components with a physical size that is independent of operating frequency.
SUMMARY
An active phased array architecture may replace traditional distributed and GaAs implementations for the necessary functions required to operate electronically steerable phased array antennas. The architecture combines active versions of vector generators, power splitters, power combiners, and/or RF hybrids in a novel fashion to realize a fully or substantially monolithic solution for a wide range of antenna applications that can be realized with radiating elements having dual-polarized feeds.
Overall, an active antenna polarizer is a digitally controlled active implementation for processing an RF signal. In accordance with an exemplary receive embodiment, the polarization and amplitude of the RF signal communicated through a phased array radiating element is adjustable by operating multiple vector generators in parallel and feeding one or both output signals of the multiple vector generators to the radiating element in spatially orthogonal fashion. In various embodiments, two output beams can have independent polarization and beam steering. The phased array antenna is configured to electrically change between polarizations and/or support beam steering. For example, the phased array antenna may alternate between linear polarization, elliptical polarization, and circular polarization. In accordance with an exemplary embodiment, in order to operate in these different polarizations, vector generators control the relative phase of the antenna signal. In an exemplary embodiment, the basic transmit embodiment and receive embodiment are used in any frequency band and with different polarizations.
In an exemplary embodiment, a phased array antenna comprises multiple subcircuits in communication with multiple radiating elements. The radio frequency signals are adjusted for both polarization control and beam steering. In a receive embodiment, multiple RF signals are received and combined into at least one receive beam output. In a transmit embodiment, at least one transmit beam input is divided and transmitted through multiple radiating elements.
In an exemplary embodiment, the phased array antenna provides multi-beam formation over multiple operating frequency bands. The phased array antenna replaces traditional distributed components and GaAs functions with active components to operate an electronically steerable multiple beam phased array antenna. The wideband nature of the active components allows for operation over multiple frequency bands simultaneously. Furthermore, the antenna polarization may be static or dynamically controlled at the subarray or radiating element level.
Advantages of the exemplary phased array antenna include increased system capacity and flexibility. Furthermore, an antenna that can operate over multiple frequency bands optimizes system availability. This system may be implemented in mobile applications, or fixed position applications where multiple systems are desired. Also, a single antenna can communicate with multiple systems and/or users, allowing for increased capacity and availability.



BRIEF DESCRIPTION OF THE DRAWING FIGURES
A more complete understanding of the present invention may be derived by referring to the detailed description and claims when considered in connection with the drawing figures, wherein like reference numbers refer to similar elements throughout the drawing figures, and:
FIG. 1 illustrates a prior art example of a phased array antenna element and control electronics;
FIG. 2 illustrates a prior art example of an antenna with polarization switching;
FIG. 3 illustrates an example embodiment of an active power splitter;
FIG. 4 illustrates an example embodiment of an active power combiner;
FIG. 5 illustrates an example embodiment of an active vector generator;
FIG. 6 illustrates an example embodiment of an active RF hybrid;
FIG. 7 illustrates an example embodiment of an active antenna signal polarizer;
FIG. 8 illustrates an example embodiment of a phased array antenna with horizontal linear polarization for transmit mode;
FIG. 9 illustrates an example embodiment of a phased array antenna with dual linear polarization for transmit mode;
FIG. 10 illustrates an example embodiment of a phased array antenna with horizontal linear polarization for receive mode;
FIG. 11 illustrates an example embodiment of a phased array antenna with dual linear polarization for receive mode;
FIG. 12 illustrates an example embodiment of a phased array antenna with differentially fed horizontal linear polarization for transmit mode;
FIG. 13 illustrates an example embodiment of a phased array antenna with differentially fed dual linear polarization for transmit mode;
FIG. 14 illustrates an example embodiment of a phased array antenna with differentially fed horizontal linear polarization for receive mode;
FIG. 15 illustrates an example embodiment of a phased array antenna with differentially fed dual linear polarization for receive mode;
FIG. 16 illustrates an example embodiment of a phased array integrated circuit configured as a 1-beam, 4-element transmitter;
FIG. 17 illustrates an example embodiment of a phased array integrated circuit configured as a 1-beam, 4-element receiver;
FIG. 18 illustrates an example embodiment of a phased array integrated circuit configured as a 2-beam, 4-element receiver;
FIG. 19 illustrates an example embodiment of a phased array integrated circuit configured as a 2-beam, 4-element transmitter;
FIG. 20 illustrates an example embodiment of a phased array integrated circuit configured as a 4-beam, 4-element receiver;
FIG. 21 illustrates an example embodiment of a phased array integrated circuit configured as a 4-beam, 4-element transmitter;
FIG. 22 illustrates another example embodiment of a phased array integrated circuit configured as a 2-beam, 4-element receiver;
FIG. 23 illustrates an example embodiment of a multi-beam architecture;
FIG. 24 illustrates an example embodiment of a dual-polarization multi-beam receive architecture;
FIG. 25 illustrates another example embodiment of a dual-polarization multi-beam receive architecture;
FIG. 26 illustrates an example embodiment of a dual-polarization multi-beam transmit architecture;
FIG. 27 illustrates another example embodiment of a dual-polarization multi-beam transmit architecture;
FIG. 28 illustrates an example embodiment of color distribution;
FIGS. 29A-29C illustrate various satellite spot beam multicolor agility methods in accordance with example embodiments;
FIG. 30 illustrates an example embodiment of a phased array antenna with slant polarization for receive mode;
FIG. 31 illustrates an example embodiment of a phased array antenna with slant polarization for transmit mode;
FIG. 32 illustrates an example embodiment of a phased array antenna with dual-beam slant polarization for receive mode;
FIG. 33 illustrates an example embodiment of a phased array antenna with dual-beam slant polarization for transmit mode;
FIG. 34 illustrates an example embodiment of a phased array integrated circuit configured as a 4-beam, 1-element receiver;
FIG. 35 illustrates an example embodiment of a phased array integrated circuit configured as a 4-beam, 1-element transmitter;
FIG. 36 illustrates an example embodiment of a phased array integrated circuit configured as a 2-beam, 1-element receiver with independent polarization;
FIG. 37 illustrates an example embodiment of a phased array integrated circuit configured as a 2-beam, 1-element transmitter with independent polarization;
FIG. 38 illustrates an example embodiment of a phased array integrated circuit configured as a 4-beam, 1-element receiver with independent polarization;
FIG. 39 illustrates an example embodiment of a phased array integrated circuit configured as a 4-beam, 1-element transmitter with independent polarization;
FIG. 40 illustrates an example embodiment of a phased array integrated circuit configured as a 2-beam, 4-element receiver with independent polarization;
FIG. 41 illustrates an example embodiment of a phased array integrated circuit configured as a 2-beam, 4-element transmitter with independent polarization;
FIGS. 42A-42B illustrate an example embodiment of a phased array integrated circuit configured as a 4-beam, 4-element receiver with independent polarization; and
FIGS. 43A-43B illustrate an example embodiment of a phased array integrated circuit configured as a 4-beam, 4-element transmitter with independent polarization.



DETAILED DESCRIPTION OF THE INVENTION
While exemplary embodiments are described herein in sufficient detail to enable those skilled in the art to practice the invention, it should be understood that other embodiments may be realized and that logical material, electrical, and mechanical changes may be made without departing from the spirit and scope of the invention. Thus, the following detailed description is presented for purposes of illustration only.
An electronically steerable phased array antenna may be used in various scenarios. For example, the phased array antenna may be implemented in COTM antennas, SATCOM airborne terminals, SATCOM mobile communications, and SATCOM earth terminals. In an exemplary embodiment, a phased array antenna comprises a layout of various active component building blocks, such as baluns, power splitters, power combiners, hybrids, and vector generators. Although throughout the application reference may be made to “active power splitters, vector generators, and active power combiners” in various exemplary embodiments, only one or more of those devices may be used in various embodiments, as opposed to all three devices.
A phased array antenna generally comprises multiple radiating elements, with each radiating element having a polarization component. In an exemplary embodiment, the radiating element has spatially orthogonal linear polarizations, spatially and electrically orthogonal circular polarizations, or spatially orthogonal and electrically non-orthogonal elliptical polarizations. In an exemplary embodiment, a phased array antenna comprises various components. The various components may include a vector generator, an active power splitter, an active power combiner, or the like. Furthermore, in an exemplary embodiment, the phased array antenna comprises a patch antenna. Though a patch antenna is illustrated in the figures and described herein, other types of radiating elements may be implemented. Such radiating elements include a fragmented radiator, a feed horn antenna, a slot antenna, and the like.
In an exemplary embodiment, each radiating element has two feed ports and results in an unbalanced feed system. In yet another exemplary embodiment, each radiating element has three feed ports and results in a partially balanced feed system. In another exemplary embodiment, each radiating element has four feed ports and results in a fully balanced feed system.
In an exemplary embodiment, a phased array antenna with two feed ports is configured to generate and control different polarizations. Exemplary polarization states include a single circular polarization state, a single elliptical polarization state, a single linear polarization state, and two orthogonal linear polarization states.
The radiating elements may be in communication with an RF integrated circuit (RFIC). In an exemplary embodiment, the RFIC is configured to divide, alter, and re-combine the basis polarizations to other orthogonal polarization states. The RF signal corresponding to the net polarization state in the RFIC may additionally be combined in a beam-forming network of the array.
Active Splitter:
FIG. 3 illustrates a schematic of an exemplary active power splitter. In an exemplary embodiment, an active power splitter 300 comprises a differential input subcircuit 310, a first differential output subcircuit 320, and a second differential output sub circuit 330. The differential input subcircuit 310 has paired transistors 311, 312 with a common emitter node and is constant current biased, as is typical in a differential amplifier. An input signal is communicated to the base of paired transistors 311, 312 in the differential input subcircuit 310. Both the first and second differential output subcircuits 320, 330 comprise a pair of transistors with a common base node and each common base is connected to ground.
The first differential output subcircuit 320 has a first transistor 321 emitter connected to the collector of one of the input subcircuit transistors 312. The emitter of the second output subcircuit transistor 322 is connected to the collector of the other input subcircuit transistor 311. In the exemplary embodiment, the first output is drawn from the collectors of transistors 321, 322 of the first differential output subcircuit 320. Furthermore, the second differential output subcircuit 330 is similarly connected, except the transistor 331, 332 emitters are inversely connected to the input subcircuit transistor 311, 312 collectors with respect to transistors 321, 322.
By inverting the input subcircuit transistor collector connections between the first and second differential output subcircuits, the first output and the second output are approximately 180° out of phase with each other. In another exemplary embodiment, transistor 331, 332 emitters are non-inversely connected to input subcircuit transistor 311, 312 collectors, causing the first output and the second output to be approximately in phase with each other. In general, the absolute phase shift of the output signals through the power splitter is not as important as the relative phasing between the first and second output signals.
In an exemplary embodiment, active power splitter 300 converts an input RF signal into two output signals. The output signal levels may be equal in amplitude, though this is not required. For a prior art passive power splitter, each output signal would be about 3 dB lower in power than the input signal. In contrast, an exemplary active splitter, such as active power splitter 300, can provide gain and the relative power level between the input signal and output signal is adjustable and can be selectively designed. In an exemplary embodiment, the output signal is configured to achieve a substantially neutral or positive power gain over the input signal. For example, the output signal may achieve a 3 dB signal power gain over the input signal. In an exemplary embodiment, the output signal may achieve a power gain in the 0 dB to 5 dB range. Moreover, the output signal may be configured to achieve any suitable power gain.
In accordance with an exemplary embodiment, active power splitter 300 produces output signals with a differential phase between the two signals that is zero or substantially zero. The absolute phase shift of output signals through the active power splitter may not be as important as the differential phasing between the output signals.
In another exemplary embodiment, active power splitter 300 additionally provides matched impedances at the input and output ports. The matched impedances may be 50 ohms, 75 ohms, or other suitable impedances. Furthermore, in an exemplary embodiment, active power splitter 300 provides isolation between the output ports of the active power splitter. In one exemplary embodiment, active power splitter 300 is manufactured as a radio frequency integrated circuit (RFIC) with a compact size that is independent of the operating frequency due to a lack of distributed components.
Active Combiner:
In an exemplary embodiment and with reference to FIG. 4, an active power combiner 400 comprises a first differential input subcircuit 410, a second differential input subcircuit 420, a single ended output subcircuit 430, and a differential output subcircuit 440. Each differential input subcircuit 410, 420 includes two pairs of transistors, with each transistor of each differential input subcircuit 410, 420 having a common emitter node with constant current biasing, as is typical in a differential amplifier.
A first input signal is communicated to the bases of the transistors in first differential input subcircuit 410. For example, a first line of input signal ml is provided to one transistor of each transistor pair in first differential input subcircuit 410, and a second line of input signal ml is provided to the other transistor of each transistor pair. Similarly, a second input signal is communicated to the bases of the transistors in second differential input subcircuit 420. For example, a first line of input signal In2 is provided to one transistor of each transistor pair in first differential input subcircuit 420, and a second line of input signal In2 is provided to the other transistor of each transistor pair. Furthermore, in an exemplary embodiment, a differential output signal is formed by a combination of signals from collectors of transistors in first and second differential input subcircuits 410, 420.
In an exemplary embodiment, active power combiner 400 converts two input RF signals into a single output signal. The output signal can either be a single ended output at single ended output subcircuit 430, or a differential output at differential output subcircuit 440. In other words, active power combiner 400 performs a function that is the inverse of active power splitter 300. The input signal levels can be of arbitrary amplitude and phase. Similar to an active power splitter, active power combiner 400 can provide gain and the relative power level between the inputs and output is also adjustable and can be selectively designed. In an exemplary embodiment, the output signal achieves a substantially neutral or positive signal power gain over the input signal. For example, the output signal may achieve a 3 dB power gain over the sum of the input signals. In an exemplary embodiment, the output signal may achieve a power gain in the 0 dB to 5 dB range. Moreover, the output signal may achieve any suitable power gain.
In an exemplary embodiment, active power combiner 400 additionally provides matched impedances at the input and output ports. The matched impedances may be 50 ohms, 75 ohms, or other suitable impedances. Furthermore, in an exemplary embodiment, active power combiner 400 provides isolation between the input ports of the power combiner. In one exemplary embodiment, active power combiner 400 is manufactured as a RFIC with a compact size that is independent of the operating frequency due to a lack of distributed components.
Vector Generator:
In an exemplary embodiment, a vector generator converts an RF input signal into an output signal (sometimes referred to as an output vector) that is shifted in phase and/or amplitude to a desired level. This replaces the function of a typical phase shifter and adds the capability of amplitude control. In other words, a vector generator is a magnitude and phase control circuit. In the exemplary embodiment, the vector generator accomplishes this function by feeding the RF input signal into a quadrature network resulting in two output signals that differ in phase by about 90°. The two output signals are fed into parallel quadrant select circuits, and then through parallel variable gain amplifiers (VGAs). In an exemplary embodiment, the quadrant select circuits receive commands and may be configured to either pass the output signals with no additional relative phase shift between them or invert either or both of the output signals by an additional 180°. In this fashion, all four possible quadrants of the 360° continuum are available to both orthogonal signals. The resulting composite output signals from the current summer are modulated in at least one of amplitude and phase.
In accordance with an exemplary embodiment and with reference to FIG. 5, a vector generator 500 comprises a passive I/Q generator 510, a first VGA 520 and a second VGA 521, a first quadrant select 530 and a second quadrant select 531 each configured for phase inversion switching, and a current summer 540. The first quadrant select 530 is in communication with I/Q generator 510 and first VGA 520. The second quadrant select 531 is in communication with I/Q generator 510 and second VGA 521. Furthermore, in an exemplary embodiment, vector generator 500 comprises a digital controller 550 that controls a first digital-to-analog converter (DAC) 560 and a second DAC 561. The first and second DACs 560, 561 control first and second VGAs 521, 520, respectively. Additionally, digital controller 550 controls first and second quadrant selects 530, 531.
In an exemplary embodiment, vector generator 500 controls the phase and amplitude of an RF signal by splitting the RF signal into two separate vectors, the in-phase (I) vector and the quadrature-phase (Q) vector. In one embodiment, the RF signal is communicated differentially. The differential RF signal communication may be throughout vector generator 500 or limited to various portions of vector generator 500. In another exemplary embodiment, the RF signals are communicated non-differentially. The I vector and Q vector are processed in parallel, each passing through the phase inverting switching performed by first and second quadrant selects 530, 531. The resultant outputs of the phase inverting switches comprise four possible signals: a non-inverted I, an inverted I, a non-inverted Q, and an inverted Q. In this manner, all four quadrants of a phasor diagram are available for further processing by VGAs 520, 521. In an exemplary embodiment, two of the four possible signals non-inverted I, inverted I, non-inverted Q, and inverted Q are processed respectively through VGAs 520, 521, until the two selected signals are combined in current summer 540 to form a composite RF signal. The current summer 540 outputs the composite RF signal with phase and amplitude adjustments. In an exemplary embodiment, the composite RF signal is in differential signal form. In another exemplary embodiment, the composite RF signals are in single-ended form.
In an exemplary embodiment, control for the quadrant shifting and VGA functions is provided by a pair of DACs. In an exemplary embodiment, reconfiguration of digital controller 550 allows the number of phase bits to be digitally controlled after vector generator 500 is fabricated if adequate DAC resolution and automatic gain control (AGC) dynamic range exists. In an exemplary embodiment with adequate DAC resolution and AGC dynamic range, any desired vector phase and amplitude can be produced with selectable fine quantization steps using digital control. In another exemplary embodiment, reconfiguration of DACs 560, 561 can be made after vector generator 500 is fabricated in order to facilitate adjustment of the vector amplitudes.
Active RF Hybrid:
In an exemplary embodiment, and with reference to FIG. 6, an active RF hybrid 600 comprises a first active power splitter 610, a second active power splitter 611, a first vector generator 620, a second vector generator 621, a first active power combiner 630, a second active power combiner 631, a first digital-to-analog converter (DAC) 640 and a second DAC 641. In accordance with the exemplary embodiment, first active power splitter 610 receives an input at Port 1 and communicates the input to first vector generator 620 and second active power combiner 631. Likewise, second active power splitter 611 receives an input at Port 2 and communicates the input to second vector generator 621 and first active power combiner 630. Vector generators 620, 621 are controlled in part by respective DACs 640, 641. In an exemplary embodiment, a 4-bit DAC is used but any number of bits many be used.
Furthermore, the output of first vector generator 620 is communicated to first active power combiner 630, and the output of second vector generator 621 is communicated to second active power combiner 631. In the exemplary embodiment, first active power combiner 630 receives input from first vector generator 620 and second active power splitter 611, and outputs a signal to Port 3. Similarly, second active power combiner 631 receives input from second vector generator 621 and first active power splitter 610, and outputs a signal to Port 4.
Active RF hybrid 600 may be used to replace various distributed components, such as a branchline coupler, Lange coupler, directional coupler, or 180° hybrid. In accordance with an exemplary embodiment, an active RF hybrid provides similar functionality in comparison to a traditional distributed hybrid. For example, active RF hybrid 600 may be dynamically configured to have variable phase differences between the output ports, which could be 90°, 180°, or some other phase difference. Another example is that active RF hybrid 600 provides port-to-port isolation and matched impedances at the input/output ports. Additional information regarding active RF hybrids is disclosed in the U.S. patent application Ser. No. 12/759,043, entitled “ACTIVE HYBRIDS FOR ANTENNA SYSTEMS,” filed Apr. 13, 2010, which is hereby incorporated by reference.
Furthermore, the active RF hybrid 600 has various advantages over a traditional passive distributed hybrid. In an exemplary embodiment, the active RF hybrid 600 does not result in a loss of power, but instead has a gain or is at least gain neutral. In another exemplary embodiment, the active RF hybrid 600 does not rely on distributed elements and is capable of operating over very wide bandwidths. In yet another exemplary embodiment, the active RF hybrid 600 implements identical building block components as used in an exemplary active phased array architecture. In one exemplary embodiment, the active RF hybrid 600 is manufactured as a monolithic microwave integrated circuit (MMIC) with a compact size that is independent of the operating frequency due to a lack of distributed components.
The components described above may be implemented in various phased array antenna embodiments. The various phased array antenna embodiments include variations on transmit or receive embodiments, number of beams, different polarizations including linear, circular, and elliptical, and the use of single ended signals or differentially fed signals.
In an exemplary embodiment, an electronically steerable phased array antenna comprises a radiating element array, an active vector generator, and a DAC. In one exemplary embodiment, the DAC is reconfigurable to operate the phased array antenna in numerous configurations. For example, the phased array antenna can support multiple frequency bands and be reprogrammed to change between different polarization types. The reconfiguration can be made after the antenna architecture is fabricated.
In accordance with an exemplary embodiment, a phased array antenna comprises active components manufactured on silicon germanium (SiGe) in a monolithic solution. Other materials may be used, such as GaAs, silicon, or other suitable materials now known or hereinafter devised. A monolithic SiGe embodiment using active components results in certain advantages over the distributed/passive network in the prior art, including lower cost, smaller physical size, wider operating bandwidths, and the ability to provide power gain rather than a power loss.
Additionally, other advantages over the prior art embodiments are possible, depending on the phased array architecture. Some of the advantages include extensive system flexibility and very compact antenna systems because no distributed structures are required. In one embodiment, the size of the control function components of the phased array architecture is compact and independent of operating frequency. Furthermore, some embodiments employ differential signaling to improve signal isolation when the RF signal is in analog form.
Some of the main advantages include that RF signals undergo a neutral or slight positive gain when being communicated through the antenna system, rather than losses that occur in the passive prior art systems. Another advantage is that the antenna system is not band limited. In other words, the antenna system is applicable to all frequency bands, including X, K, Ku, Ka, and Q bands. Furthermore, in an exemplary embodiment, the antenna system is configured to operate, after manufacture or installation, at a first frequency range and subsequently operate at a second frequency range not equal to the first frequency range. In another exemplary embodiment, the antenna system is configured to operate at the first frequency range and the second frequency range simultaneously. In an exemplary embodiment, multi-band antennas are a practical option as a product.
Reconfigurability of the antenna system is also an advantage. This includes the ability to reconfigure the number of phase bits over full product life, being able to reconfigure the amplitude taper of the system over full product life, and being able to reconfigure the system polarization over full product life.
Described below are various specific phased array antenna system embodiments. The embodiments vary in terms of polarization, transmit or receive modes, and whether differential signaling is implemented.
Active Antenna Polarizer:
Overall, an active antenna polarizer is a digitally controlled active implementation for processing an RF signal. In accordance with an exemplary embodiment, the polarization and amplitude of a phased array radiating element is adjustable by operating two vector generators in parallel and feeding both output signals of the two vector generators to the radiating element in a spatially orthogonal fashion. The phased array antenna is configured to electrically change between polarizations. For example, the phased array antenna may alternate between linear polarization and circular polarization. In a first embodiment, the system achieves linear polarization by using a single vector generator to drive the radiating element. In a second embodiment, the system achieves circular polarization by using two vector generators to drive the radiating element in a spatially orthogonal fashion with two vectors that are electrically 90° out of phase from each other. In a third embodiment, the system achieves elliptical polarization by using two vector generators to drive the radiating element in a spatially orthogonal fashion with two vectors that are electrically out of phase by a value other than 90° with each other.
In an exemplary embodiment, the active antenna polarizer comprises discrete active components. In another exemplary embodiment, an active polarizer comprises a monolithic solution of active components. In yet another exemplary embodiment, the active antenna polarizer comprises a combination of discrete components and a monolithic solution.
In an exemplary embodiment and with reference to FIG. 7, a transmit active antenna polarizer 700 comprises an active power splitter 710, two vector generators 720, 721, and two DACs 730, 731. An RF input signal is actively split and transmitted through two vector generators 720, 721 in parallel. The vector generators 720, 721 are controlled by DACs 730, 731 respectively, and each vector generator produces a linear output signal. These two linear outputs can be used to energize/drive the spatially orthogonal feed ports of a radiating element (not shown).
The transmit active antenna polarizer 700 may be considered a basic transmit embodiment, which is configured to be implemented in a variety of different phased array antenna architectures. In an exemplary embodiment, the basic transmit embodiment is used in any frequency band and with different polarizations. For example, and as described below, the basic transmit embodiment may be used as the basis for at least one of beam steering and the phased array antenna transmitting in linear polarization, circular polarization, or elliptical polarization. In accordance with an exemplary embodiment, in order to operate in these different polarizations, vector generators 720, 721 control the phase of the antenna signal. In another embodiment, vector generators 720, 721 are configured for beam steering in conjunction with polarization control.
In an exemplary embodiment, reconfiguration of DACs 730, 731 allows the number of phase bits to be digitally controlled after transmit active antenna polarizer 700 is fabricated if adequate DAC resolution and AGC dynamic range exists. In an exemplary embodiment with adequate DAC resolution and AGC dynamic range, any desired vector phase and amplitude can be produced with selectable fine quantization steps using digital control. In another exemplary embodiment, reconfiguration of DACs 730, 731 can be made after transmit active antenna polarizer 700 is fabricated in order to facilitate adjustment of the signal amplitudes.
Reconfigurability of the antenna system is also an advantage. In an exemplary embodiment, the antenna system includes the ability to reconfigure the number of phase bits in a DAC over full product life. In another exemplary embodiment, the antenna system is able to reconfigure the amplitude taper of the system over full product life. In yet another exemplary embodiment, the antenna system is able to reconfigure the system polarization over full product life. Moreover, in an exemplary embodiment with adequate DAC resolution and AGC dynamic range, any desired vector phase and amplitude can be produced with selectable fine quantization steps using digital control.
In an exemplary embodiment, the vector generators are controlled by software and digital hardware, and the antenna polarization is software definable. In other words, software may be implemented to control the antenna polarization by modifying the operating parameters of the vector generators via the DACs or other digital control. The operating parameters, for example, may include the relative phase between the outputs of the vector generators. In an exemplary embodiment, software controls the phase change by programming the DACs to achieve the desired phase relationship. Moreover, in an exemplary embodiment, the polarization of the energy radiated from the antenna is controlled in real-time. This results in a completely electronic technique where software allows continuous dynamic adjustment of the polarization of dual polarization feed antennas.
A receive active antenna is similar to a transmit active antenna as already described. In an exemplary embodiment, two RF input signals are communicated from a radiating element. The two RF input signals are processed in parallel through two vector generators before being combined by an active combiner. A receive active antenna polarizer may be considered a basic receive embodiment which is configured to be implemented in a variety of different phased array antenna architectures. In an exemplary embodiment, the basic receive embodiment is used in any frequency band and with different polarizations. For example, the basic receive embodiment may be used as the basis for at least one of beam steering and the phased array antenna receiving in linear polarization, circular polarization, or elliptical polarization. In accordance with an exemplary embodiment, in order to operate in these different polarizations, the vector generators control the phase of the antenna signal as described herein.
In accordance with an exemplary embodiment, an active antenna polarizer is configured to dynamically change the polarization of an antenna using radiating elements with dual-polarized feeds. Furthermore, in an exemplary embodiment, an antenna is configured to statically or dynamically control the polarization of the antenna on a subarray or individual element basis in order to optimize a performance characteristic associated with polarization. Examples of such polarization associated characteristics include polarization loss factors and polarization efficiency. In an exemplary embodiment, the use of dual-polarized feeds facilitates the performance optimization. For example, in an exemplary embodiment, a maximum signal level may be obtained by varying the polarization around an expected value until the optimal level is set. The difference between the expected value and the optimal value may occur due to various factors. For example, objects may be present in the signal path. As another example, manufacturing tolerances may result in the physical structure being in a less-optimal position. In still another example, inclement weather can result in one polarization performing better than another polarization. In other words, an exemplary antenna is configured to adjust the polarization in order to compensate for manufacturing tolerances, weather, inferring objects, and the like. In an exemplary embodiment, a polarization sweep is performed in order to receive different signals which can be used for signal identification.
FIG. 8 shows an exemplary embodiment of a phased array antenna 800 configured to transmit a signal with linear polarization. Phased array antenna 800 comprises an active power splitter 810, a first vector generator 820, a second vector generator 821, a first DAC 830, and a second DAC 831. Phased array antenna 800 is a basic transmit embodiment with an output signal of first vector generator 820 energizing a radiating element 801 and with second vector generator 821 not in communication with radiating element 801. In an alternative but similar embodiment, second vector generator 821 energizes radiating element 801 with first vector generator 820 not in communication with radiating element 801. Additionally, radiating element 801 can have a “horizontal” orientation or a “vertical” orientation. In the exemplary embodiment, the basic transmit embodiment with two vector generators 820, 821 is implemented in order to demonstrate that a standard architecture may be used in numerous antenna types. This enables cost benefits because the same underlying component is used instead of different, more customized components.
In another exemplary embodiment, a phased array antenna, configured to transmit a signal with linear polarization, comprises only one vector generator and a controlling DAC. As one skilled in the art understands, the embodiments described herein that manipulate only one vector generator output can comprise only a single vector generator. In other words, in one embodiment, phased array antenna 800 comprises first vector generator 820 but not second vector generator 821 or active power splitter 810.
In contrast, a dual linear polarization antenna communicates two signals to a radiating element. In an exemplary embodiment and with reference to FIG. 9, a phased array antenna 900 is configured to transmit a signal with dual linear polarization. Phased array antenna 900 comprises an active power splitter 910, a first vector generator 920, a second vector generator 921, a first DAC 930, and a second DAC 931. Phased array antenna 900 is a basic transmit embodiment with the two vector generator output signals energizing a radiating element 901, in both the horizontal and vertical orientations. Furthermore, the output signals of vector generators 920, 921 can have any relative phase between the two signals. In a circular polarization embodiment, the output signal of vector generator 920 has a +/−90° relative phase difference with the output signal of vector generator 921 when energizing radiating element 901. In an exemplary embodiment with elliptical polarization, the output signal of vector generator 920 has a relative phase difference other than +/−90° with the output signal of vector generator 921 when energizing radiating element 901.
FIG. 10 shows an exemplary embodiment of a phased array antenna 1000 configured to receive a signal with linear polarization. Phased array antenna 1000 comprises an active power combiner 1010, a first vector generator 1020, a second vector generator 1021, a first DAC 1030 and a second DAC 1031. Phased array antenna 1000 is a basic receive embodiment with one of vector generators 1020, 1021 communicating a signal from a radiating element 1001 to active power combiner 1010 and the other of vector generators 1020, 1021 not being in communication with radiating element 1001. Additionally, radiating element 1001 can have a horizontal or vertical orientation.
In another exemplary embodiment, a phased array antenna is configured to receive a signal with linear polarization and comprises only one vector generator and corresponding controlling DAC. As would be known to one skilled in the art, various embodiments described herein that manipulate only one vector generator output may comprise only one vector generator. In other words, in one embodiment, phased array antenna 1000 comprises first vector generator 1020 but not second vector generator 1021 or active combiner 1010.
In contrast, a dual linear polarization antenna communicates two signals from a radiating element. In an exemplary embodiment and with reference to FIG. 11, a phased array antenna 1100 is configured to receive a signal with dual linear polarization. Phased array antenna 1100 comprises an active power combiner 1110, a first vector generator 1120, a second vector generator 1121, a first DAC 1130, and a second DAC 1131. Phased array antenna 1100 is a basic receive embodiment with vector generators 1120, 1121 receiving individual polarized signals from radiating element 1101 as input signals. The individual polarized signals may be a horizontal oriented signal and a vertical oriented signal. Furthermore, the input signals of vector generators 1120, 1121 can have any relative phase between the two signals. In a circular polarization embodiment, the input signal of vector generator 1120 has a +/−90° relative phase difference with the input signal of vector generator 1121 when received from radiating element 1101. In an exemplary embodiment with elliptical polarization, the input signal of vector generator 1120 has a relative phase difference other than +/−90° with the input signal of vector generator 1121 when received from radiating element 1101.
FIG. 12 shows an exemplary embodiment of a phased array antenna 1200 configured to transmit a signal with differentially fed linear polarization. Phased array antenna 1200 comprises an active power splitter 1210, a first vector generator 1220, a second vector generator 1221, a first DAC 1230 and a second DAC 1231. Phased array antenna 1200 is a basic transmit embodiment with a differential output signal from one of vector generators 1220, 1221 energizing a radiating element 1201. As is known to one in the art, a differential signal has two signals are 180° out of phase from each other. In various embodiments, the differential signal may be fed into the “horizontal” portions of radiating element 1201 or into the “vertical” portions of radiating element 1201.
In another exemplary embodiment, a phased array antenna configured to transmit a differential signal with linear polarization comprises only one vector generator and a controlling DAC. As one skilled in the art understands, the embodiments described herein that manipulate only one vector generator output can comprise only a single vector generator. In other words, in one embodiment, phased array antenna 1200 comprises first vector generator 1220 but not second vector generator 1221 or active power splitter 1210.
In contrast, a dual linear polarization antenna communicates two differentially fed signals to a radiating element. In an exemplary embodiment and with reference to FIG. 13, a phased array antenna 1300 is configured to transmit differential signals with dual linear polarization. Phased array antenna 1300 comprises an active power splitter 1310, a first vector generator 1320, a second vector generator 1321, a first DAC 1330, and a second DAC 1331. Phased array antenna 1300 is a basic transmit embodiment with a first differentially fed output signal of vector generator 1320 and a second differentially fed output signal of vector generator 1321 energizing a radiating element 1301. In an exemplary embodiment, the first differentially fed output signal is fed into radiating element 1301 in a vertical orientation. Furthermore, in the exemplary embodiment, the second differentially fed output signal is fed into radiating element 1301 in a horizontal orientation. Moreover, the first differentially fed output signal of vector generator 1320 and the second differentially fed output signal of vector generator 1321 can have any relative phase between the two signals. In a circular polarization embodiment, the first differentially fed output signal of vector generators 1320 has a +/−90° relative phase difference with the second differentially fed output signal of vector generator 1321 when energizing radiating element 1301. In an exemplary embodiment with elliptical polarization, the first differentially fed output signal of vector generator 1320 has a relative phase difference other than +/−90° with the second differentially fed output signal of vector generator 1321 when energizing radiating element 1301.
FIG. 14 shows an exemplary embodiment of a phased array antenna 1400 configured to receive a signal with differentially fed horizontal linear polarization. Phased array antenna 1400 comprises an active power combiner 1410, a first vector generator 1420, a second vector generator 1421, a first DAC 1430 and a second DAC 1431. Phased array antenna 1400 is a basic receive embodiment with one of vector generators 1420, 1421 receiving a differential input signal from a radiating element 1401 and communicating an output signal to active power combiner 1410. In one embodiment, and similar to phased array antenna 800, the other of vector generators 1420, 1421 is not in communication with radiating element 1401. Furthermore, the differential signal may be received from the “horizontal” portions of radiating element 1401 or from the “vertical” portions of radiating element 1401.
In another exemplary embodiment, a phased array antenna is configured to receive a signal with differentially fed horizontal linear polarization and comprises only one vector generator and corresponding controlling DAC. As would be known to one skilled in the art, various embodiments described herein that manipulate only one vector generator input may comprise only one vector generator. In other words, in one embodiment, phased array antenna 1400 comprises first vector generator 1420 but not second vector generator 1421 or active combiner 1410.
In contrast, a dual linear polarization antenna communicates two differentially fed signals from a radiating element. In an exemplary embodiment and with reference to FIG. 15, a phased array antenna 1500 is configured to receive differential signals with dual linear polarization. Phased array antenna 1500 comprises an active power combiner 1510, a first vector generator 1520, a second vector generator 1521, a first DAC 1530, and a second DAC 1531. Phased array antenna 1500 is a basic receive embodiment with vector generator 1520 receiving a first differentially fed input signal and vector generator 1521 receiving a second differentially fed input signal from a radiating element 1501. In an exemplary embodiment, the first differentially fed input signal is received from radiating element 1501 in a vertical orientation. Furthermore, in the exemplary embodiment, the second differentially fed input signal is received from radiating element 1501 in a horizontal orientation. Moreover, the first and second differentially fed input signals of vector generators 1520, 1521 can have any relative phase between the two signals. In a circular polarization embodiment, the first differentially fed input signal of vector generator 1520 has a +/−90° relative phase difference with the second differentially fed input signal of vector generator 1521 when received from radiating element 1501. In an exemplary embodiment with elliptical polarization, the first differentially fed output signal of vector generator 1520 has a relative phase difference other than +/−90° with the second differentially fed output signal of vector generator 1521 when energizing radiating element 1501.
The various phased array antenna embodiments described above may be implemented into multiple radiating element architecture. Furthermore, the multiple radiating elements are scalable in terms of both radiating elements and beam forming. An embodiment with vector generators in communication with individual radiating elements facilitates additional beams while using the same radiating aperture. Furthermore, the radiating element transmitter/receiver may comprise various numbers of radiating elements. For example, the antenna architecture could comprise multiple radiating elements in the range of 2-20.
In accordance with an exemplary embodiment, and with reference to FIG. 16, a phased array integrated circuit (IC) 1600 is configured as a 4-radiating element transmitter. The phased array IC 1600 comprises a first subcircuit 1610 in communication with a first radiating element 1611, a second subcircuit 1620 in communication with a second radiating element 1621, a third subcircuit 1630 in communication with a third radiating element 1631, and a fourth subcircuit 1640 in communication with a fourth radiating element 1641. Each subcircuit 1610, 1620, 1630, 1640 receives an input signal and transmits the signal to the spatially orthogonal ports of the respective radiating element 1611, 1621, 1631, 1641.
In accordance with an exemplary embodiment, an RF input signal is provided to phased array IC 1600. In an exemplary embodiment, multiple splitters are used to divide the RF input signal that is communicated to each of four subcircuits 1610, 1620, 1630, 1640 as input signals. In a more specific exemplary embodiment, a balun may be implemented to convert the RF input signal into a differential RF input signal. Differential signaling may improve signal isolation and interference rejection if the RF signal is in analog form. An active splitter 1653 is configured to divide the differential RF input signal into two separate signals that are communicated to an active splitter 1651 and an active splitter 1652, respectively. At the next stage, active splitter 1651 is configured to divide the communicated signal and communicate the divided signals to first subcircuit 1610 and second subcircuit 1620. Similarly, active splitter 1652 is configured to divide the communicated signals and communicate the divided signals to third subcircuit 1630 and fourth subcircuit 1640.
The structure and function of each subcircuit 1610, 1620, 1630, 1640 is substantially similar. Thus, only first subcircuit 1610 will be discussed in detail. Moreover, subcircuit 1610 is substantially similar to transmit active antenna polarizer 700. In accordance with an exemplary embodiment, first subcircuit 1610 comprises a first vector generator 1612 controlled by a first DAC (not shown), a second vector generator 1613 controlled by a second DAC (not shown), and an active splitter 1615. Though the signals communicated in phased array IC 1600 may be described as differential, the signals may also be single-ended. Active splitter 1615 receives a differential signal from active splitter 1651, and divides the differential signal once again. In an exemplary embodiment, vector generators 1612, 1613 individually receive a differential signal from active splitter 1615. Furthermore, vector generators 1612, 1613 are configured to adjust the phase and polarization of the signals to be transmitted so that individual beam steering and polarization control may be achieved. Vector generators 1612, 1613 afford two degrees of freedom to polarization track and beam steer. For circular or elliptical polarization and single beam steering, one of the vector generators can provide the beam steering while the other vector generator can provide an offset phase to track the polarization.
The polarized signals are then communicated from vector generators 1612, 1613 to the spatially orthogonal ports of radiating element 1611 for transmission. In an exemplary embodiment, a digital control 1601 communicates polarization and beam steering commands to vector generators 1612, 1613 via the respective DACs.
In addition to a 1-beam, 4-radiating element transmitter, a similar structure may be configured as a 1-beam, 4-radiating element receiver. In an exemplary embodiment and with reference to FIG. 17, a phased array integrated circuit 1700 is configured as a 1-beam, 4-radiating element receiver. The phased array IC 1700 comprises a first subcircuit 1710 in communication with a first radiating element 1711, a second subcircuit 1720 in communication with a second radiating element 1721, a third subcircuit 1730 in communication with a third radiating element 1731, and a fourth subcircuit 1740 in communication with a fourth radiating element 1741. Each subcircuit 1710, 1720, 1730, 1740 receives a pair of spatially orthogonal RF signals from the respectively coupled radiating element 1711, 1721, 1731, 1741 and generates a single output signal.
The structure and function of each subcircuit 1710, 1720, 1730, 1740 is substantially similar. Thus, only first subcircuit 1710 will be discussed in detail. In accordance with an exemplary embodiment, first subcircuit 1710 has a polarization tracking and single beam steering portion comprising two vector generators 1712, 1713. The two vector generators 1712, 1713 are configured to receive the RF input signal from radiating element 1711, provide beam steering, track the polarization of the signals, and communicate the vector generator output signals to an active power combiner 1715. Vector generators 1712, 1713 afford two degrees of freedom to polarization track and beam steer. For circular or elliptical polarization and single beam steering, one of the vector generators can provide the beam steering while the other vector generator can provide an offset phase to track the polarization. The active power combiner 1715 combines the two vector generator output signals and generates a composite output signal.
In an exemplary embodiment, a digital control 1701 communicates polarization and beam steering commands to vector generators 1712, 1713, for example, via corresponding DACs.
In accordance with an exemplary embodiment, a receive beam output is generated by combining the single output signal from each of four subcircuits 1710, 1720, 1730, 1740. In an exemplary embodiment, multiple combiners are used to combine the subcircuit output signals into a receive beam. In a more specific exemplary embodiment, an active combiner 1751 is configured to combine the single outputs from first and second subcircuits 1710, 1720. Also in the exemplary embodiment, an active combiner 1752 is configured to combine the single outputs from third and fourth subcircuits 1730, 1740. At the next stage, an active combiner 1753 is configured to combine the combined outputs of active combiners 1751, 1752 to form a receive beam output.
In addition to a 1-beam 4-radiating element antenna, a similar structure may be configured as a 2-beam 4-radiating element antenna. In an exemplary embodiment and with reference to FIG. 18, a phased array integrated circuit 1800 is configured as a 2-beam, 4-radiating element receiver. The phased array IC 1800 comprises a first subcircuit 1810 in communication with a first radiating element 1811, a second subcircuit 1820 in communication with a second radiating element 1821, a third subcircuit 1830 in communication with a third radiating element 1831, and a fourth subcircuit 1840 in communication with a fourth radiating element 1841. Each subcircuit 1810, 1820, 1830, 1840 receives a pair of spatially orthogonal RF signals from the respectively coupled radiating element 1811, 1821, 1831, 1841 and generates two output signals, one for each beam to be formed.
The structure and function of each subcircuit 1810, 1820, 1830, 1840 is substantially similar. Thus, only first subcircuit 1810 will be discussed in detail. In accordance with an exemplary embodiment, first subcircuit 1810 has a polarization forming portion comprising two vector generators 1812, 1813. The two vector generators 1812, 1813 are configured to receive the RF input signals from radiating element 1811, polarization track the signals, and transmit the vector generator output signals to an active power combiner 1815. The active power combiner 1815 combines the two vector generator output signals and generates a composite intermediate signal. The composite intermediate signal is communicated from active power combiner 1815 to an active power splitter 1816. The active power splitter 1816 divides the intermediate signal into two signals, one for each beam, with each of the two output signals passing through a beam forming portion of subcircuit 1810. The beam forming portion comprises two vector generators 1818, 1819, whose outputs represent independently steered beam components to be combined in the respective beam forming network. In an exemplary embodiment, a digital control 1801 communicates polarization and beam steering commands to vector generators 1812, 1813, 1818, 1819.
In accordance with an exemplary embodiment, a first receive beam output is generated by combining one of the two output signals from each of four subcircuits 1810, 1820, 1830, 1840. A second receive beam output is generated by combining the second of the two output signals from each of four subcircuits 1810, 1820, 1830, 1840. In an exemplary embodiment, multiple combiners are used to combine the subcircuit output signals into a first receive beam output and a second receive beam output.
In a more specific exemplary embodiment, an active combiner 1851 is configured to combine the first of the two outputs from first and second subcircuits 1810, 1820. Furthermore, an active combiner 1861 is configured to combine the second of the two outputs from first and second subcircuits 1810, 1820. Also in the exemplary embodiment, an active combiner 1852 is configured to combine the first of the two outputs from third and fourth subcircuits 1830, 1840. An active combiner 1862 is configured to combine the second of the two outputs from third and fourth subcircuits 1830, 1840.
At the next stage, an active combiner 1853 is configured to combine the combined outputs of active combiners 1851 and 1852 to form a first receive beam output. Furthermore, an active combiner 1863 is configured to combine the combined outputs of active combiners 1861 and 1862 to form a second receive beam output.
In addition to a 2-beam, 4-radiating element receiver, a similar structure may be configured as a 2-beam, 4-radiating element transmitter. In an exemplary embodiment, and with reference to FIG. 19, a phased array integrated circuit 1900 is configured as a 2-beam, 4-radiating element transmitter. The phased array IC 1900 comprises a first subcircuit 1910 in communication with a first radiating element 1911, a second subcircuit 1920 in communication with a second radiating element 1921, a third subcircuit 1930 in communication with a third radiating element 1931, and a fourth subcircuit 1940 in communication with a fourth radiating element 1941. Each subcircuit 1910, 1920, 1930, 1940 receives two input signals and transmits signals to the spatially orthogonal ports of the respectively coupled radiating element 1911, 1921, 1931, 1941.
In accordance with an exemplary embodiment, a first transmit beam and a second transmit beam are provided to phased array IC 1900. In an exemplary embodiment, multiple splitters are used to divide the first and second transmit beams that are communicated to each of four subcircuits 1910, 1920, 1930, 1940 as input signals.
In a more specific exemplary embodiment, an active splitter 1953 is configured to divide the first transmit beam input into two separate signals that are communicated to an active splitter 1951 and an active splitter 1952, respectively. Similarly, an active splitter 1963 is configured to divide the second transmit beam input into two separate signals that are communicated to an active splitter 1961 and an active splitter 1962, respectively.
At the next stage, active splitters 1951, 1961 are configured to divide the communicated signals and communicate the divided signals to first subcircuit 1910 and second subcircuit 1920. The active splitters 1952, 1962 are configured to divide the communicated signals and communicate the divided signals to third subcircuit 1930 and fourth subcircuit 1940.
The structure and function of each subcircuit 1910, 1920, 1930, 1940 is substantially similar. Thus, only first subcircuit 1910 will be discussed in detail. In accordance with an exemplary embodiment, first subcircuit 1910 has a beam forming portion comprising two vector generators 1918, 1919. The two vector generators 1918, 1919 are configured to individually receive an input signal from active splitters 1951, 1961, respectively and adjust the phase according to beam steering commands.
An active power combiner 1915 combines the two phase-adjusted signals and generates a composite phase-adjusted intermediate signal. The composite phase-adjusted intermediate signal is communicated from active power combiner 1915 to an active power splitter 1916. The active power splitter 1916 divides the intermediate signal into two splitter output signals, with each of the two splitter output signals passing through a polarization modifying portion of first subcircuit 1910. The polarization modifying portion comprises vector generators 1912, 1913, and is configured to polarize the output signals to the desired polarization. The polarized signals are then communicated to the spatially orthogonal ports of radiating element 1911 for transmission. In an exemplary embodiment, a digital control 1901 communicates polarization and beam steering commands to vector generators 1912, 1913, 1918, 1919.
In an exemplary embodiment and with reference to FIG. 20, a phased array integrated circuit 2000 is configured as a 4-beam, 4-radiating element receiver. The phased array IC 2000 comprises a first subcircuit 2010 in communication with a first radiating element 2011, a second subcircuit 2020 in communication with a second radiating element 2021, a third subcircuit 2030 in communication with a third radiating element 2031, and a fourth subcircuit 2040 in communication with a fourth radiating element 2041. Each subcircuit 2010, 2020, 2030, 2040 receives a pair of spatially orthogonal RF signals from the respectively coupled radiating element 2011, 2021, 2031, 2041 and generates four output signals, one for each beam to be formed.
The structure and function of each subcircuit 2010, 2020, 2030, 2040 is substantially similar. Thus, only first subcircuit 2010 will be discussed in detail. In accordance with an exemplary embodiment, first subcircuit 2010 has a polarization tracking portion comprising two vector generators 2012, 2013. The two vector generators 2012, 2013 are configured to receive the RF input signal from radiating element 2011, track the polarization of the signals, and transmit vector generator signal outputs to an active power combiner 2014. The active power combiner 2014 combines the two vector generator signal outputs and generates a composite intermediate signal. The composite intermediate signal is communicated from active power combiner 2014 to an active power splitter 2015. The active power splitter 2015 divides the intermediate signal into four signals, with each of the four output signals passing through a beam forming portion of subcircuit 2010. The beam forming portion comprises four vector generators 2016, 2017, 2018 2019, whose outputs represent independently steered beam components to be combined in the respective beam forming network. In an exemplary embodiment, a digital control 2001 communicates polarization and beam steering commands to vector generators 2012, 2013, 2016, 2017, 2018, 2019.
In accordance with an exemplary embodiment, a first receive beam output is generated by combining one of the four output signals from each of four subcircuits 2010, 2020, 2030, 2040. A second receive beam output is generated by combining a second of the four output signals from each of four subcircuits 2010, 2020, 2030, 2040. A third receive beam output is generated by combining a third of the four output signals from each of four subcircuits 2010, 2020, 2030, 2040. A fourth receive beam output is generated by combining a fourth of the four output signals from each of four subcircuits 2010, 2020, 2030, 2040. In an exemplary embodiment, multiple combiners are used to combine the subcircuit output signals into the four receive beam outputs.
In a more specific exemplary embodiment, an active combiner 2051 is configured to combine the first of the four outputs from first and second subcircuits 2010, 2020. Furthermore, an active combiner 2061 is configured to combine the second of the four outputs from first and second subcircuits 2010, 2020. Likewise, an active combiner 2071 is configured to combine the third of the four outputs from first and second subcircuits 2010, 2020. An active combiner 2081 is configured to combine the fourth of the four outputs from first and second subcircuits 2010, 2020.
Also in the exemplary embodiment, an active combiner 2052 is configured to combine the first of the two outputs from third and fourth subcircuits 2030, 2040. An active combiner 2062 is configured to combine the second of the four outputs from third and fourth subcircuits 2030, 2040. Furthermore, an active combiner 2072 is configured to combine the third of the four outputs from third and fourth subcircuits 2030, 2040. An active combiner 2082 is configured to combine the fourth of the four outputs from third and fourth subcircuits 2030, 2040.
At the next stage, an active combiner 2053 is configured to combine the combined outputs of active combiners 2051, 2052 to form a first receive beam output. An active combiner 2063 is configured to combine the combined outputs of active combiners 2061, 2062 to form a second receive beam output. Furthermore, an active combiner 2073 is configured to combine the combined outputs of active combiners 2071, 2072 to form a third receive beam output. An active combiner 2083 is configured to combine the combined outputs of active combiners 2081, 2082 to form a fourth receive beam output.
In an exemplary embodiment, and with reference to FIG. 21, a phased array integrated circuit 2100 is configured as a 4-beam, 4-radiating element transmitter. The phased array IC 2100 comprises a first subcircuit 2110 in communication with a first radiating element 2111, a second subcircuit 2120 in communication with a second radiating element 2121, a third subcircuit 2130 in communication with a third radiating element 2131, and a fourth subcircuit 2140 in communication with a fourth radiating element 2141. Each subcircuit 2110, 2120, 2130, 2140 receives four input signals and transmits RF signals to the spatially orthogonal ports of the respectively coupled radiating element 2111, 2121, 2131, 2141.
In accordance with an exemplary embodiment, a first, second, third, and fourth transmit beam are provided to phased array IC 2100. In an exemplary embodiment, multiple splitters are used to divide the first, second, third, and fourth transmit beams that are communicated to each of four subcircuits 2110, 2120, 2130, 2140 as input signals.
In a more specific exemplary embodiment, an active splitter 2153 is configured to divide the first transmit beam input into two separate signals that are communicated to an active splitter 2151 and an active splitter 2152, respectively. Similarly, an active splitter 2163 is configured to divide the second transmit beam input into two separate signals that are communicated to an active splitter 2161 and an active splitter 2162, respectively. In an exemplary embodiment, an active splitter 2173 is configured to divide the third transmit beam input into two separate signals that are communicated to an active splitter 2171 and an active splitter 2172, respectively. Furthermore, an active splitter 2183 is configured to divide the fourth transmit beam input into two separate signals that are communicated to an active splitter 2181 and an active splitter 2182, respectively.
At the next stage, active splitters 2151, 2161, 2171, 2181 are configured to divide the communicated signals and communicate the divided signals to first subcircuit 2110 and second subcircuit 2120. The active splitters 2152, 2162, 2172, 2182 are configured to divide the communicated signals and communicate the divided signals to third subcircuit 2130 and fourth subcircuit 2140.
The structure and function of each subcircuit 2110, 2120, 2130, 2140 is substantially similar. Thus, only first subcircuit 2110 will be discussed in detail. In accordance with an exemplary embodiment, first subcircuit 2110 has a beam forming portion comprising four vector generators 2116, 2117, 2118, 2119. The four vector generators 2116, 2117, 2118, 2119 are configured to individually receive an input signal from active splitters 2151, 2161, 2171, 2181, respectively and adjust the phase according to beam steering commands.
An active power combiner 2114 combines the four phase-adjusted signals and generates a composite phase-adjusted intermediate signal. The composite phase-adjusted intermediate signal is communicated from active power combiner 2114 to an active power splitter 2115. The active power splitter 2115 divides the intermediate signal into two signals, with each of the two output signals passing through a polarization modifying portion of first subcircuit 2110. The polarization modifying portion comprises vector generators 2112, 2113, and is configured to polarize the output signals to the desired polarization. The polarized signals are then communicated to the spatially orthogonal ports of radiating element 2111 for transmission. In an exemplary embodiment, a digital control 2101 communicates polarization and beam steering commands to vector generators 2112, 2113, 2116, 2117, 2118, 2119, for example, via DACs.
In addition to the various embodiments described above, other architectures are possible. For example, in an exemplary embodiment and with reference to FIG. 22, a phased array integrated circuit 2200 is configured as a 2-beam, 4-radiating element receiver for circular or elliptical polarizations. As illustrated in a first subcircuit 2210 of phased array IC 2200, the difference between phased array IC 1810 is that only one vector generator 2212 is present in the polarization forming portion. A single vector generator 2212 is sufficient for polarization tracking of circular or elliptical polarizations. In an exemplary embodiment, vector generator 2212 tracks the polarizations by providing the 90° offset (or non-90° phase offset if elliptical) to the phase of the signal appearing at the alternate spatially orthogonal port of radiating element 2211. The rest of phased array IC 2200 is similar to phased array IC 1810, and will not be described in detail though various components are similarly referenced. Similar variations are possible in the embodiments illustrated in FIGS. 19-21, with circular or elliptical polarization embodiments using only a single vector generator for polarization tracking.
Multi-Beam Operation:
In addition to the multiple radiating elements embodiments described above, various beam forming networks may be designed using multiple radiating elements and forming multiple beams. In accordance with an exemplary embodiment and with reference to FIG. 23, a multi-beam architecture 2300 comprises multiple radiating elements (RE1, RE2, . . . REN) with each radiating element being in communication with an active polarization control (PC1, PC2, . . . PCN). The multi-beam architecture 2300 further comprises at least one beam forming network (BFN1, BFN2, . . . BFNM) and at least one phase shifter connected to the active polarization control (PC1, PC2, . . . PCN) per beam forming network (BFN1, BFN2, . . . BFNM). In an exemplary embodiment, each radiating element is in communication with M phase shifters, and each phase shifter is in communication with one of M beam forming networks so that each beam forming network receives a signal from each of the N radiating elements.
In an exemplary embodiment, the phase shifters may be active vector generators or any other component suitable to phase shift the signals. Furthermore, the beam forming networks and summing junctions can be passive or active. Moreover, a multi-beam architecture may similarly be implemented for transmission of RF signals.
With further reference to FIG. 23, the active polarization control functions (PC1, PC2, . . . PCN) can be any of the embodiments previously listed herein. Connected to each of the active polarization control functions is a power splitter (for receive applications) or power combiner (for transmit applications). The power splitter or power combiner can be implemented as a passive or active structure as described previously herein. In communication with the power splitter/combiner is a set of vector generators where each vector generator provides a phase shift in support of a particular beam. In an exemplary embodiment, there are M vector generators at each radiating element to support M independently steerable beams. In an exemplary embodiment, the set of vector generators is in communication with a power combiner (for receive applications) or power splitter (for transmit applications) to complete the beam formation process. The power splitter or power combiner can be implemented as a passive or active structure as described previously herein.
In different various embodiments, a multi-beam multi-band architecture with a beam forming network in communication with a single radiating element is configured for forming and detecting circular polarized signals.
Receive Architecture:
In accordance with an exemplary embodiment and with reference to FIG. 24, dual-polarization multi-beam receive architecture 2400 comprises active power splitters, vector generators, and active power combiners in communication with a radiating element 2401 to form multiple beams. In an exemplary embodiment, receive architecture 2400 forms at least one right-hand circular polarized (RHCP) beam and forms at least one left-hand circular polarized (LHCP) beam. More specifically, in an exemplary embodiment, receive architecture 2400 forms N RHCP beams and forms M LHCP beams.
Each beam, whether right-hand polarized or left-hand polarized, is formed using a similar component configuration. In an exemplary embodiment, a signal is received at radiating element 2401, having a horizontal polarization and a vertical polarization. The vertical polarized signal is communicated to a first active power splitter 2410 and the horizontal polarized signal is communicated to a second active power splitter 2411. Moreover, first active power splitter 2410 may be understood to comprise multiple active power splitters, and second active power splitter 2411 may be understood to comprise the same number of multiple active power splitters. In an exemplary embodiment, active power splitters 2410, 2411 individually divide the signal into two or more signals, such that the vertical signal polarization and horizontal signal polarization are divided into a certain number of signals.
In an exemplary embodiment, each beam is formed using a first vector generator 2420, a second vector generator 2421, and an active power combiner 2430. The first vector generator 2420 receives a vertical polarized signal from first active power splitter 2410. First vector generator 2420 is configured to adjust at least one of the phase and amplitude of the vertical polarized signal for beam steering. Furthermore, second vector generator 2421 receives a horizontal polarized signal from second active power splitter 2411. Second vector generator 2421 is configured to adjust at least one of the phase and amplitude of the horizontal polarized signal for polarization tracking. In other embodiments, the vertical polarized signal is adjusted for polarization tracking and the horizontal polarized signal is adjusted for beam steering. In accordance with an exemplary embodiment, active power combiner 2430 receives two output signals, one signal from first vector generator 2420 and another signal from second vector generator 2421. Active power combiner 2430 combines the two signals into a beam. The beam may be RHCP or LHCP, depending on the parameters of vector generators 2420, 2421. In an exemplary embodiment, receive architecture 2400 is configured to provide complete polarization flexibility on a beam by beam basis. However, receive architecture 2400 uses 2*(M+N) vector generators to accomplish this complete flexibility.
In a circular polarization embodiment, fewer components are used in comparison to a complete polarization embodiment because circular polarization only needs +/−90° polarization tracking. Therefore, in an exemplary embodiment and with reference to FIG. 25, a dual-polarization multi-beam receive architecture 2500 with circular polarization comprises active power splitters and vector generators in communication with a radiating element 2501 to form multiple beams.
In an exemplary embodiment, receive architecture 2500 forms at least one RHCP beam and forms at least one LHCP beam. As with the complete polarization embodiment, receive architecture 2500 may form up to N RHCP beams and M LHCP beams. Each beam, whether right-hand polarized or left-hand polarized, is formed using a similar component configuration. In an exemplary embodiment, a signal is received at radiating element 2501, having a horizontal polarization component and a vertical polarization component. The vertical polarized signal is communicated to a first active power splitter 2510 and the horizontal polarized signal is communicated to a second active power splitter 2511. Moreover, first active power splitter 2510 may be understood to comprise multiple active power splitters, and second active power splitter 2511 may be understood to comprise the same number of multiple active power splitters. In an exemplary embodiment, active power splitters 2510, 2511 individually divide the signal into two or more signals, such that the vertical signal polarization and horizontal signal polarization are divided into a certain number of signals.
In an exemplary embodiment, each beam is formed using a vector generator 2520 and a quadrature allpass filter (QAF) 2540. In an exemplary embodiment, QAF 2540 receives a vertical polarized signal from first active power splitter 2510 and a horizontal polarized signal from second active power splitter 2511. QAF 2540 combines the vertical and horizontal polarized signals while injecting a nominally 90° relative phase shift between the two signals. The combined output signal is communicated from QAF 2540 to vector generator 2520. Vector generator 2520 is configured to provide beam steering by adjusting at least one of the phase and amplitude of the combined signal.
The beam may be RHCP or LHCP, depending on the signal input connections with QAF 2540. For example, to generate a RHCP beam, a vertical polarized signal is connected to an I vector input of QAF 2540 and a horizontal polarized signal is connected to a Q vector input of QAF 2540. In contrast, to generate a LHCP beam, a vertical polarized signal is connected to the Q vector input of QAF 2540 and a horizontal polarized signal is connected to the I vector input of QAF 2540. In an exemplary embodiment, receive architecture 2500 provides circular polarization on each beam using (M+N) vector generators.
In another exemplary embodiment, a simpler component configuration of a dual-polarization multi-beam receive architecture with circular polarization is possible. Similar to receive architecture 2500, in an exemplary embodiment, a receive architecture comprises a first active power splitter, a second active power splitter and a modified vector generator in communication with a radiating element. However, in contrast to receive architecture 2500, no quadrature allpass filters are used. For each beam, and still using receive architecture 2500 as a reference, QAF 2540 is eliminated in conjunction with eliminating the QAF at the input of vector generator 2520, resulting in a modified vector generator.
The elimination of the two QAF components is a result of redundancy. In receive architecture 2500, QAF 2540 receives two input vectors, referred to as a Q vector and an I vector for convenience. With reference to similar vector generator 500, vector generator 2520 also comprises a QAF that is separate and reversed from QAF 2540. In vector generator 2520, the QAF receives a single signal and generates a Q vector and an I vector. In an exemplary embodiment, the cascade of two reversed QAFs performs a redundant function and may be eliminated. In the exemplary embodiment, the vertical and horizontal polarized signals from the radiating element are connected to the phase inversion switches of a modified vector generator. The elimination of QAFs is possible if the QAFs are originally reversed of each other. In other words, reversed back-to-back QAFs injecting opposite phase shifts counteract each other and become expendable.
Eliminating the two QAFs achieves system advantages, such as eliminating the ohmic loss associated with each QAF, which may be about 3 dB. Another advantage is that the QAF is a bandwidth limiting element of the vector generator, resulting in the modified vector generator being capable of an expanded bandwidth.
Transmit Architecture:
In accordance with an exemplary embodiment and with reference to FIG. 26, dual-polarization multi-beam transmit architecture 2600 comprises active power splitters, vector generators, and active power combiners in communication with a radiating element 2601 to form a dual polarized transmit signal from multiple input beams. In an exemplary embodiment, transmit architecture 2600 generates a dual polarized transmit signal from at least one RHCP beam and from at least one LHCP beam. More specifically, in an exemplary embodiment, transmit architecture 2600 inputs include N RHCP beams and M LHCP beams.
Each beam, whether right-hand polarized or left-hand polarized, is added to the dual polarized output signal using a similar component configuration. In an exemplary embodiment, an active power splitter 2610 receives a beam having either right-hand or left-hand circular polarization and divides the beam into two divided signals. A first vector generator 2620 receives one of the two divided signals at the input. A second vector generator 2621 receives the other of the two divided signals at the input. First vector generator 2620 is configured to adjust at least one of the phase and amplitude of the divided signal for beam steering. Second vector generator 2621 is configured to adjust at least one of the phase and amplitude of the divided signal for polarization tracking. In other embodiments, first vector generator 2620 performs polarization tracking and second vector generator 2621 performs beam steering.
Furthermore, in an exemplary embodiment first vector generator 2620 generates a vertically polarized signal that is combined with other vertically polarized signals in a first active power combiner 2630. The combined output signal of first active power combiner 2630 is transmitted to radiating element 2601 as a vertical polarization signal. Moreover, in the exemplary embodiment second vector generator 2621 generates a horizontally polarized signal that is combined with other horizontally polarized signals in a second active power combiner 2631. The combined output signal of second active power combiner 2631 is transmitted to radiating element 2601 as a horizontal polarization signal. Active power combiner 2630 may be understood to comprise multiple active power combiners, and second active power combiner 2631 may be understood to comprise the same number of multiple active power combiners. In an exemplary embodiment, transmit architecture 2600 is configured to provide complete polarization flexibility on a beam by beam basis. However, transmit architecture 2600 uses 2*(M+N) vector generators to accomplish this complete flexibility.
In a circular polarization embodiment, fewer components are used in comparison to a complete polarization embodiment because circular polarization only needs +/−90° polarization tracking. Therefore, in an exemplary embodiment and with reference to FIG. 27, a dual-polarization multi-beam transmit architecture 2700 with circular polarization comprises vector generators and active power combiners in communication with a radiating element 2701 to form a dual polarized transmit signal from multiple input beams. In an exemplary embodiment, transmit architecture 2700 generates a dual polarized transmit signal from at least one RHCP beam and from at least one LHCP beam. As with the complete polarization embodiment, transmit architecture 2700 inputs include N RHCP beams and M LHCP beams.
Each beam, whether right-hand polarized or left-hand polarized, is added to the dual polarized output signal using a similar component configuration. In an exemplary embodiment, a vector generator 2720 receives an input beam. Vector generator 2720 is configured to adjust at least one of the phase and amplitude of the input beam. The output signal of vector generator 2720 is communicated to a QAF 2740. In an exemplary embodiment, QAF 2740 divides output signal into a vertical signal and a horizontal signal while injecting a nominally 90° relative phase shift between the two signals to generate vertical and horizontal polarizations.
Furthermore, in an exemplary embodiment QAF 2740 generates a vertically polarized signal that is combined with other vertically polarized signals in a first active power combiner 2730. The combined output signal of first active power combiner 2730 is transmitted to radiating element 2701 as a vertical polarization signal. Moreover, in the exemplary embodiment QAF 2740 also generates a horizontally polarized signal that is combined with other horizontally polarized signals in a second active power combiner 2731. The combined output signal of second active power combiner 2731 is transmitted to radiating element 2701 as a horizontal polarization signal. Active power combiner 2730 may be understood to comprise multiple active power combiners, and second active power combiner 2731 may be understood to comprise the same number of multiple active power combiners.
In an exemplary embodiment, transmit architecture 2700 adjusts for the input beam having either RHCP or LHCP by alternating which output signal of QAF 2740 is communicated to each active power combiner. For example, and as illustrated in FIG. 27, for a RHCP beam, a vertical polarized signal is connected to an I vector output of QAF 2740. In contrast, for a LHCP, a vertical polarized signal is connected to a Q vector output of QAF 2740. In an exemplary embodiment, transmit architecture 2700 forms a dual polarized output signal from circular polarized input beams using (M+N) vector generators.
Although FIGS. 24-27 illustrate a one dimensional phased array, a two dimensional phased array is also contemplated and would be understood by one skilled in the art in light of the disclosure.
Slant Polarization:
Moreover, in accordance with various embodiments, a phased array antenna may communicate one or more signals using slant linear polarization, which may be referred to as ±45 degree polarization. Slant linear polarization can be generated through simultaneous excitation of physically orthogonal feeds of an antenna. Slant linear polarization can be generated by dividing RF power equally between the two orthogonal feeds while selecting a desired phase relationship between the two feeds. In order to generate a horizontal polarization, the input ports are driven in phase and the two feeds are summed. In order to generate a vertical polarization, the two ports are driven 180 degrees out of phase and the two feeds are summed.
In an exemplary embodiment and with reference to FIG. 30, a phased array antenna 3000 is configured to receive a signal with slant linear polarization. Phased array antenna 3000 comprises an active power combiner 3010, a first active vector generator 3020, a second active vector generator 3021, a first DAC 3030, and a second DAC 3031. Phased array antenna 3000 is a basic receive embodiment with active vector generators 3020, 3021 receiving individual polarized signals from radiating element 3001 as input signals. The individual polarized signals may be a first feed signal oriented at +45° and a second feed signal oriented at −45°. In accordance with various embodiments, a horizontal polarized signal can be generated by maintaining the first feed signal in phase when passing through first active vector generator 3020 and maintaining the second feed signal in phase when passing through second active vector generator 3021. The first and second feed signals are summed at active power combiner 3010 to form the horizontal polarized signal. Similarly, and in accordance with various embodiments, a vertical polarized signal can be generated by maintaining the first feed signal in phase when passing through first active vector generator 3020 and injecting a 180° phase difference in the second feed signal at the second active vector generator 3021. The first feed signal and the inverted second feed signal are summed at active power combiner 3010 to form the vertical polarized signal.
With reference to DACs 3030, 3031 of FIG. 31, the active vector generators 3020, 3021 are controlled in part by respective DACs 3030, 3031. In an exemplary embodiment, a 4-bit DAC is used but any number of bits many be used. In various embodiments, reconfiguration of DACs 3030, 3031 allows the number of phase bits to be digitally controlled after phased array antenna 3000 is fabricated if adequate DAC resolution and AGC dynamic range exists. In an exemplary embodiment with adequate DAC resolution and AGC dynamic range, any desired vector phase and amplitude can be produced with selectable fine quantization steps using digital control. In another exemplary embodiment, reconfiguration of DACs 3030, 3031 can be made after phased array antenna 3100 is fabricated in order to facilitate adjustment of the signal phases.
In an exemplary embodiment and with reference to FIG. 31, a phased array antenna 3100 is configured to receive an input signal and transmit as slant linear polarized signal. Phased array antenna 3100 comprises an active power splitter 3110, a first active vector generator 3120, a second active vector generator 3121, a first DAC 3130, and a second DAC 3131. Phased array antenna 3100 is a basic transmit embodiment with the two active vector generator output signals energizing a radiating element 3101 in both orthogonal feeds. In accordance with various embodiments, a transmit beam input signal can be transmitted using horizontal slant polarization by splitting, at active power splitter 3110, an input signal into a first feed signal and a second feed signal. The first feed signal can be communicated with a phase angle of “Θ” in response to passing through first active vector generator 3120 and the second feed signal can be communicated with a phase angle of “Θ” in response to passing through second active vector generator 3121. The first feed signal is transmitted to one of the orthogonal feeds of radiating element 3101 and the second feed signal is transmitted to the other orthogonal feed of radiating element 3101. Similarly, in accordance with various embodiments, a transmit beam input signal can be transmitted using vertical slant polarization by splitting, at active power splitter 3110, an input signal into a first feed signal and a second feed signal. The first feed signal can be communicated with a phase angle of “Θ” in response to passing through first active vector generator 3120 and the second feed signal can be communicated with a phase angle of “Θ±180°” in response to passing through second active vector generator 3121. The first feed signal is transmitted to one of the orthogonal feeds of radiating element 3101 and the second feed signal is transmitted to the other orthogonal feed of radiating element 3101.
With reference to DACs 3130, 3131 of FIG. 31, the active vector generators 3120, 3121 are controlled in part by respective DACs 3130, 3131. In an exemplary embodiment, a 4-bit DAC is used but any number of bits many be used. In various embodiments, reconfiguration of DACs 3130, 3131 allows the number of phase bits to be digitally controlled after phased array antenna 3100 is fabricated if adequate DAC resolution and AGC dynamic range exists. In an exemplary embodiment with adequate DAC resolution and AGC dynamic range, any desired vector phase and amplitude can be produced with selectable fine quantization steps using digital control. In another exemplary embodiment, reconfiguration of DACs 3130, 3131 can be made after phased array antenna 3100 is fabricated in order to facilitate adjustment of the signal phases.
In accordance with an exemplary embodiment and with reference to FIG. 32, a slant-polarization, dual-beam receive phased array antenna 3200 comprises a first active power splitter 3210 and a second active power splitter 3211 in communication with a radiating element 3201. Phased array antenna 3200 further comprises a first active vector generator 3220 in parallel with a second active vector generator 3221, which are both in communication with first active power splitter 3210. Moreover, phased array antenna 3200 further comprises a third active vector generator 3222 in parallel with a fourth active vector generator 3223, which are both in communication with second active power splitter 3211. In an exemplary embodiment, a digital control (not shown) communicates polarization and beam steering commands to active vector generators 3220, 3221, 3222, 3223. Additionally, phased array antenna 3200 further comprises a first active power combiner 3240 and a second active power combiner 3241. First active power combiner 3240 is in communication with first active vector generator 3220 and third active vector generator 3222. Second active power combiner 3241 is in communication with second active vector generator 3221 and fourth active vector generator 3223.
In an exemplary embodiment, a signal is received at radiating element 3201 having a +45° polarization and a −45° polarization. The +45° polarized signal is communicated to first active power splitter 3210 and the −45° polarized signal is communicated to second active power splitter 3211. In an exemplary embodiment, first active power splitter 3210 is configured to divide the +45° polarized signal into two signals, and second active power splitter 3211 is configured to divide the −45° polarized signal into two signals.
In an exemplary embodiment, a first receive beam output is formed using first active vector generator 3220, third active vector generator 3222, and first active power combiner 3240. The first active vector generator 3220 receives a +45° signal from first active power splitter 3210 and third active vector generator 3222 receives a −45° signal from second active power splitter 3211. In accordance with various exemplary embodiments, first active power combiner 3240 receives two feed signals; one feed signal from first active vector generator 3220 and another feed signal from third active vector generator 3222, and forms the first receive beam output. The first feed signal of first receive beam output can be communicated with a phase angle of “Θ” in response to passing through first active vector generator 3220 and the second feed signal of the first receive beam output can be communicated with a phase angle of “Θ” or “Θ±180°” in response to passing through third active vector generator 3222. First active power combiner 3240 combines the two feed signals into the first receive beam output. The first receive beam output may be vertical or horizontal polarization, depending on the parameters of third active vector generator 3222. For example, third active vector generator 3222 communicating a “Θ” phase angle signal, if combined with a “Θ” phase angle signal from first active vector generator 3220, results in first active power combiner 3240 generating a horizontal polarized first receive beam output. Alternatively, third active vector generator 3222 communicating a “Θ+180°” phase shifted signal, if combined with a “Θ” phase angle signal from first active vector generator 3220, results in first active power combiner 3240 generating a vertical polarized first receive beam output.
Likewise, in an exemplary embodiment, a second receive beam output is formed using second active vector generator 3221, fourth active vector generator 3223, and second active power combiner 3241. The second active vector generator 3221 receives a +45° signal from first active power splitter 3210 and fourth active vector generator 3223 receives a −45° signal from second active power splitter 3211. In accordance with an exemplary embodiment, active power combiner 3241 receives two feed signals, one feed signal from second active vector generator 3221 and another feed signal from fourth active vector generator 3223. The first feed signal of the second receive beam output can be communicated with a phase angle of “Θ” in response to passing through second active vector generator 3221 and the second feed signal of the second receive beam output can be communicated with a phase angle of “Θ” or “Θ±180°” in response to passing through fourth active vector generator 3223. Second active power combiner 3241 combines the two feed signals into the second receive beam output. The second receive beam output may be vertical or horizontal polarization, depending on the parameters of fourth active vector generator 3223. For example, fourth active vector generator 3223 communicating a “Θ” phase angle signal, if combined with a “Θ” phase angle signal from second active vector generator 3221, results in second active power combiner 3241 generating a horizontal polarized second receive beam output. Alternatively, fourth active vector generator 3223 communicating a “Θ+180°” phase angle signal, if combined with a “Θ” phase angle signal from second active vector generator 3221, results in second active power combiner 3241 generating a vertical polarized second receive beam output.
In accordance with an exemplary embodiment and with reference to FIG. 33, a slant-polarization, dual-beam transmit phased array antenna 3300 comprises a first active power splitter 3310 and a second active power splitter 3311. Phased array antenna 3300 further comprises a first active vector generator 3320 in parallel with a second active vector generator 3321, where first active vector generator 3320 is in communication with first active power splitter 3310, and where second active vector generator 3321 is in communication with second active power splitter 3311. Moreover, phased array antenna 3300 further comprises a third active vector generator 3322 in parallel with a fourth active vector generator 3323, where third active vector generator 3322 is in communication with first active power splitter 3310, and where fourth active vector generator 3323 is in communication with second active power splitter 3311. Additionally, phased array antenna 3300 further comprises a first active power combiner 3340 and a second active power combiner 3341. First active power combiner 3340 is in communication with first active vector generator 3320 and second active vector generator 3321. Second active power combiner 3341 is in communication with third active vector generator 3322 and fourth active vector generator 3323. In an exemplary embodiment, a digital control (not shown) communicates polarization and beam steering commands to active vector generators 3320, 3321, 3322, 3323. Additionally, first active power combiner 3340 and second active power combiner 3341 are each in communication with a radiating element 3301.
In an exemplary embodiment, a first transmit beam input is received at first active power splitter 3310 and a second transmit beam input is received at second active power splitter 3311. The first and second transmit beams are combined at first and second active power combiners 3340, 3341, and transmitted as slant polarized signals.
In various embodiments, first active power splitter 3310 is configured to divide the first transmit beam input into two feed signals. The first feed signal of first transmit beam input can be communicated with a phase angle of “Θ” in response to passing through first active vector generator 3320 and the second feed signal of the first transmit beam input can be communicated with a phase angle of “Θ” or “Θ±180°” in response to passing through third active vector generator 3322. The first transmit beam input may be vertical or horizontal polarized, which is adjusted for depending on the parameters of third active vector generator 3322. For example, third active vector generator 3322 communicating a “Θ” phase angle signal, if combined with a “Θ” phase angle signal from first active vector generator 3320, results in the first transmit beam input having a horizontal polarization being transmitted as a slant polarized transmit beam output. Alternatively, third active vector generator 3322 communicating a “Θ+180°” phase shifted signal, if combined with a “Θ” phase angle signal from first active vector generator 3320, results in the first transmit beam input having a vertical polarization being transmitted as a slant polarized transmit beam output.
In various embodiments, second active power splitter 3311 is configured to divide the second transmit beam input into two feed signals. The first feed signal of second transmit beam input can be communicated with a phase angle of “Θ” in response to passing through second active vector generator 3321 and the second feed signal of the second transmit beam input can be communicated with a phase angle of “Θ” or “Θ±180°” in response to passing through fourth active vector generator 3323. The second transmit beam input may be vertical or horizontal polarized, which is adjusted for depending on the parameters of fourth active vector generator 3323. For example, fourth active vector generator 3323 communicating a “Θ” phase angle signal, if combined with a “Θ” phase angle signal from second active vector generator 3321, results in the second transmit beam input having a horizontal polarization being transmitted as a slant polarized transmit beam output. Alternatively, fourth active vector generator 3323 communicating a “Θ+180°” phase shifted signal, if combined with a “Θ” phase angle signal from second active vector generator 3321, results in the second transmit beam input having a vertical polarization being transmitted as a slant polarized transmit beam output.
In accordance with an exemplary embodiment, first active power combiner 3340 receives two intermediate feed signals; one intermediate feed signal from first active vector generator 3320 and another intermediate feed signal from second active vector generator 3321, and forms a +45° slant polarized transmit beam output. Likewise, in accordance with various embodiments, second active power combiner 3341 receives two intermediate feed signals; one intermediate feed signal from third active vector generator 3322 and another intermediate feed signal from fourth active vector generator 3323, and forms a −45° slant polarized transmit beam output.
Receive Architecture:
In accordance with an exemplary embodiment and with reference to FIG. 34, slant-polarization multi-beam receive architecture 3400 comprises active power splitters, active vector generators, and active power combiners in communication with a radiating element 3401 to form multiple beams. In an exemplary embodiment, receive architecture 3400 forms either a horizontal polarized beam or a vertical polarized beam. More specifically, in an exemplary embodiment, receive architecture 3400 forms N horizontal and/or vertical beams.
Each beam, whether horizontal polarized or vertical polarized, is formed using a similar component configuration. In an exemplary embodiment, two signals are received at radiating element 3401 having a +45° polarization and a −45° polarization, respectively. The +45° polarized signal is communicated to a first active power splitter 3410 and the −45° polarized signal is communicated to a second active power splitter 3411. In an exemplary embodiment, active power splitter 3410 is configured to divide the +45° polarized signal into at least two signals, and active power splitter 3411 is configured to divide the −45° polarized signal into at least two signals. Moreover, first active power splitter 3410 may be understood to comprise multiple active power splitters, and second active power splitter 3411 may be understood to comprise the same number of multiple active power splitters. In an exemplary embodiment, active power splitters 3410, 3411 individually divide the signal into two or more signals, such that the +45° polarized signal and −45° polarized signal are divided into a certain number of signals. In other words, the +45° polarized signal and −45° polarized signal are each divided into N signals.
In an exemplary embodiment, each beam is formed using a first active vector generator 3420, a second active vector generator 3421, and an active power combiner 3430. The first active vector generator 3420 receives the +45° polarized signal from first active power splitter 3410. Furthermore, second active vector generator 3421 receives the −45° polarized signal from second active power splitter 3411. In an exemplary embodiment, a digital control (not shown) communicates polarization and beam steering commands to first active vector generator 3420 and second active vector generator 3421. In accordance with an exemplary embodiment, active power combiner 3430 receives two output signals, one signal from first active vector generator 3420 and another signal from second active vector generator 3421. Active power combiner 3430 combines the two signals into an output beam. The output beam can have horizontal or vertical polarization, depending on the parameters of active vector generators 3420, 3421. For example, second active vector generator 3421 communicating a signal with phase Θ, if combined with a signal with phase Θ from first active vector generator 3420, results in first active power combiner 3430 generating a horizontal polarized first output beam. Alternatively, second active vector generator 3421 communicating a Θ±180° phase shifted signal, if combined with a signal with phase Θ from first active vector generator 3420, results in first active power combiner 3430 generating a vertical polarized first output beam. In an exemplary embodiment, receive architecture 3400 is configured to provide complete polarization flexibility between horizontal and vertical polarization on a beam by beam basis. Receive architecture 3400 uses 2*N active vector generators to accomplish this flexibility. In accordance with the various embodiments, receive architecture 3400 can include N active power combiners, N first active vector generators, and N second active vector generators. The configuration forms N receive beam outputs, with each beam output capable of switching between horizontal and vertical polarization by controlling the active vector generator phase shift to be either “Θ” or “Θ±180°.”
Transmit Architecture:
In accordance with an exemplary embodiment and with reference to FIG. 35, slant-polarization multi-beam transmit architecture 3500 comprises active power splitters, active vector generators, and active power combiners in communication with a radiating element 3501 having slant slots to form a polarized transmit signal from multiple input beams. In an exemplary embodiment, transmit architecture 3500 generates a slant-polarized transmit signal from at least one of a horizontal polarized beam or a vertical polarized beam. More specifically, in an exemplary embodiment, transmit architecture 3500 inputs include N beams, which may individually be one of horizontal or vertical beams.
Each input beam, whether horizontal polarized or vertical polarized, is added to the slant polarized output signal using a similar component configuration. In an exemplary embodiment, an active power splitter 3510 receives an input beam having either horizontal or vertical polarization and divides the input beam into two divided signals. A first active vector generator 3520 receives one of the two divided signals at the input. A second active vector generator 3521 receives the other of the two divided signals at the input. In an exemplary embodiment, a digital control (not shown) communicates polarization and beam steering commands to first active vector generator 3520 and second active vector generator 3521.
Furthermore, in an exemplary embodiment, first active vector generator 3520 communicates the one of the two divided signals with a phase of “Θ” to a first active power combiner 3530. In various embodiments, first active power combiner 3530 is configured to receive signals with a phase of “Θ” from one or more active vector generators 3520. The combined output signal of first active power combiner 3530 is transmitted to a +45° slant slot of radiating element 3501.
Moreover, in the exemplary embodiment, second active vector generator 3521 generates a polarized signal with a phase of either “Θ” or “Θ±180°,” depending on the polarization of each input beam. In response to the input beam having horizontal polarization, second active vector generator 3521 can be configured to communicate an output signal with phase of “Θ.” In response to the input beam having vertical polarization, second active vector generator 3521 can be configured to communicate an output signal with phase of “Θ±180°.” The slant polarized signal generated by second active vector generator 3521 can be combined with other slant polarized signals in a second active power combiner 3531. The combined output signal of second active power combiner 3531 is transmitted to radiating element 3501 as a −45° slant polarized signal. Active power combiner 3530 may be understood to comprise multiple active power combiners, and second active power combiner 3531 may be understood to comprise the same number of multiple active power combiners. In an exemplary embodiment, transmit architecture 3500 is configured to provide complete polarization flexibility between horizontal and vertical polarization on a beam by beam basis. Transmit architecture 3500 uses 2*N active vector generators to accomplish this complete flexibility. In accordance with the various embodiments, transmit architecture 3500 can include N active power splitters, N first active vector generators, and N second active vector generators. The configuration transmits N transmit beam inputs, with each beam input being either horizontal and vertical polarization and forming a combined output beam by controlling the active vector generator phase shift to be either “Θ” or “Θ±180°.”
Several of the phased array antenna embodiments disclosed herein relate to communicating one or more signals in various polarizations, such as linear, circular, elliptical, or slant polarization. Furthermore, in various exemplary embodiments, a phased array antenna can be configured to communicate two or more beams having independent polarization.
In accordance with an exemplary embodiment and with reference to FIG. 36, an independent polarization, dual-beam receive phased array antenna 3600 comprises a first active power splitter 3610 and a second active power splitter 3611 in communication with a radiating element 3601. Phased array antenna 3600 further comprises a first active vector generator 3620 in parallel with a second active vector generator 3621, which are both in communication with first active power splitter 3610. Moreover, phased array antenna 3600 further comprises a third active vector generator 3622 in parallel with a fourth active vector generator 3623, which are both in communication with second active power splitter 3611. In an exemplary embodiment, a digital control (not shown) communicates polarization and beam steering commands to active vector generators 3620, 3621, 3622, 3623. Additionally, phased array antenna 3600 further comprises a first active power combiner 3640 and a second active power combiner 3641. First active power combiner 3640 is in communication with first active vector generator 3620 and third active vector generator 3622. Second active power combiner 3641 is in communication with second active vector generator 3621 and fourth active vector generator 3623.
In an exemplary embodiment, a signal can be received at radiating element 3601 having a horizontal feed and having a vertical feed. The horizontal feed signal can be communicated to first active power splitter 3610 and the vertical feed signal can be communicated to second active power splitter 3611. In an exemplary embodiment, first active power splitter 3610 can be configured to divide the horizontal feed signal into two intermediate horizontal signals, and second active power splitter 3611 can be configured to divide the vertical feed signal into two intermediate vertical signals.
In an exemplary embodiment, a first receive beam output is formed using first active vector generator 3620, third active vector generator 3622, and first active power combiner 3640. The first active vector generator 3620 receives one of the intermediate horizontal signals from first active power splitter 3610 and third active vector generator 3622 receives one of the intermediate vertical signals from second active power splitter 3611. In various embodiments, first active vector generator 3620 communicates a horizontal beam signal having a beam steering angle of “Θ” to first active power combiner 3640. Further, third active vector generator 3622 communicates a vertical beam signal to first active power combiner 3640. The beam steering angle of the vertical beam signal is set based on the desired polarization of the first receive beam output. In accordance with an exemplary embodiment, first active power combiner 3640 receives two feed signals, a first feed signal from first active vector generator 3620 and a second feed signal from third active vector generator 3622. The first feed signal of first receive beam output can be communicated with a phase angle of “Θ” in response to passing through first active vector generator 3620 and the second feed signal of the first receive beam output can be communicated with a phase angle of “Θ,” “Θ+90°,” “Θ−90°,” or “Θ±180°” in response to passing through third active vector generator 3622. First active power combiner 3640 combines the two feed signals into the first receive beam output. The first receive beam output can be any polarization type, including linear, circular, elliptical, or slant polarization, depending on the parameters of first active vector generator 3620 and the parameters of third active vector generator 3622. For example, third active vector generator 3622 communicating a “Θ” phase angle signal, if combined with a “Θ” phase angle signal from first active vector generator 3620, results in first active power combiner 3640 generating a horizontal slant polarized first receive beam output. Additionally, third active vector generator 3622 communicating a “Θ+90°” phase angle signal, if combined with a “Θ” phase angle signal from first active vector generator 3620, results in first active power combiner 3640 generating a right hand circular polarized (RHCP) first receive beam output. Further, third active vector generator 3622 communicating a “Θ−90°” phase angle signal, if combined with a “Θ” phase angle signal from first active vector generator 3620, results in first active power combiner 3640 generating a left hand circular polarized (LHCP) first receive beam output. Moreover, third active vector generator 3622 communicating a “Θ±180°” phase shifted signal, if combined with a “Θ” phase angle signal from first active vector generator 3620, results in first active power combiner 3640 generating a vertical slant polarized first receive beam output.
Likewise, in an exemplary embodiment, a second receive beam output is formed using second active vector generator 3621, fourth active vector generator 3623, and second active power combiner 3641. The second active vector generator 3621 receives the other intermediate horizontal signal from first active power splitter 3610 and fourth active vector generator 3623 receives the other intermediate vertical signal from second active power splitter 3611.
In various embodiments, second active vector generator 3621 communicates a horizontal beam signal having a beam steering angle of “Θ” to second active power combiner 3641. Further, fourth active vector generator 3623 communicates a vertical beam signal to second active power combiner 3641. The beam steering angle of the horizontal beam signal is set based on the desired polarization of the second output beam. In accordance with various exemplary embodiments, second active power combiner 3641 receives two feed signals, a first feed signal from second active vector generator 3621 and a second feed signal from fourth active vector generator 3623. The first feed signal of second receive beam output can be communicated with a phase angle of “Θ” in response to passing through second active vector generator 3621 and the second feed signal of the second receive beam output can be communicated with a phase angle of “Θ,” “Θ+90°,” “Θ−90°,” or “Θ±180°” in response to passing through fourth active vector generator 3623. Second active power combiner 3641 combines the two feed signals into the second receive beam output. The second receive beam output can be any polarization type, including linear, circular, elliptical, or slant polarization, depending on the parameters of second active vector generator 3621 and the parameters of fourth active vector generator 3623. For example: fourth active vector generator 3623 communicating a “Θ” phase angle signal, if combined with a “Θ” phase angle signal from second active vector generator 3621, results in second active power combiner 3641 generating a horizontal slant polarized first receive beam output. Additionally, fourth active vector generator 3623 communicating a “Θ+90°” phase angle signal, if combined with a “Θ” phase angle signal from second active vector generator 3621, results in second active power combiner 3641 generating a right hand circular polarized (RHCP) first receive beam output. Further, fourth active vector generator 3623 communicating a “Θ−90°” phase angle signal, if combined with a “Θ” phase angle signal from second active vector generator 3621, results in second active power combiner 3641 generating a left hand circular polarized (LHCP) first receive beam output. Moreover, fourth active vector generator 3623 communicating a “Θ±180°” phase shifted signal, if combined with a “Θ” phase angle signal from second active vector generator 3621, results in second active power combiner 3641 generating a vertical slant polarized first receive beam output.
In accordance with an exemplary embodiment and with reference to FIG. 37, an independent-polarization, dual-beam transmit phased array antenna 3700 comprises a first active power combiner 3740 and a second active power combiner 3741, each in communication with a radiating element 3701. Phased array antenna 3700 further comprises a first active vector generator 3720 in parallel with a second active vector generator 3721, which are both in communication with first active power combiner 3740. Moreover, phased array antenna 3700 further comprises a third active vector generator 3722 in parallel with a fourth active vector generator 3723, which are both in communication with second active power combiner 3741. In an exemplary embodiment, a digital control (not shown) communicates polarization and beam steering commands to active vector generators 3720, 3721, 3722, 3723. Additionally, phased array antenna 3700 further comprises a first active power splitter 3710 and a second active power splitter 3711. First active power splitter 3710 is in communication with first active vector generator 3720 and third active vector generator 3722. Similarly, second active power splitter 3711 is in communication with second active vector generator 3721 and fourth active vector generator 3723.
In an exemplary embodiment, a first transmit beam input is received at first active power splitter 3710 and a second transmit beam input is received at second active power splitter 3711. The first and second transmit beam inputs are combined at first and second active power combiners 3740, 3741, and transmitted as independently polarized signals. In an exemplary embodiment, first active power splitter 3710 is configured to divide the first transmit beam input into a pair of first transmit beam intermediate signals, and second active power splitter 3711 is configured to divide the second transmit beam input into a pair of second transmit intermediate signals.
In various embodiments, first active power splitter 3710 is configured to divide the first transmit beam input into two feed signals. The first feed signal of first transmit beam input can be communicated with a phase angle of “Θ” in response to passing through first active vector generator 3720 and the second feed signal of the first transmit beam input can be communicated with a phase angle of “Θ,” “Θ+90°,” “Θ−90°,” or “Θ±180°” in response to passing through third active vector generator 3722. The first transmit beam can be any polarization type, including linear, circular, elliptical, or slant polarization, depending on the parameters of first active vector generator 3720 and the parameters of third active vector generator 3722. For example, third active vector generator 3722 communicating a “Θ” phase angle signal, if combined with a “Θ” phase angle signal from first active vector generator 3720, results in the first transmit beam being transmitted as a horizontal slant polarized transmit beam output. Additionally, third active vector generator 3722 communicating a “Θ+90°” phase angle signal, if combined with a “Θ” phase angle signal from first active vector generator 3720, results in the first transmit beam being transmitted as a RHCP transmit beam output. Further, third active vector generator 3722 communicating a “Θ−90°” phase angle signal, if combined with a “Θ” phase angle signal from first active vector generator 3720, results in the first transmit beam being transmitted as a LHCP transmit beam output. Moreover, third active vector generator 3722 communicating a “Θ+180°” phase shifted signal, if combined with a “Θ” phase angle signal from first active vector generator 3720, results in the first transmit beam input being transmitted as a vertical slant polarized transmit beam output.
Similarly, in various embodiments, second active power splitter 3711 is configured to divide the second transmit beam input into two feed signals. The first feed signal of second transmit beam input can be communicated with a phase angle of “Θ” in response to passing through second active vector generator 3721 and the second feed signal of the second transmit beam input can be communicated with a phase angle of “Θ,” “Θ+90°,” “Θ−90°,” or “Θ±180°” in response to passing through fourth active vector generator 3723. The second transmit beam can be any polarization type, including linear, circular, elliptical, or slant polarization, depending on the parameters of second active vector generator 3721 and the parameters of fourth active vector generator 3723. For example, fourth active vector generator 3723 communicating a “Θ” phase angle signal, if combined with a “Θ” phase angle signal from second active vector generator 3721, results in the second transmit beam being transmitted as a horizontal slant polarized transmit beam output. Additionally, fourth active vector generator 3723 communicating a “Θ+90°” phase angle signal, if combined with a “Θ” phase angle signal from second active vector generator 3721, results in the second transmit beam being transmitted as a RHCP transmit beam output. Further, fourth active vector generator 3723 communicating a “Θ−90°” phase angle signal, if combined with a “Θ” phase angle signal from second active vector generator 3721, results in the second transmit beam being transmitted as a LHCP transmit beam output. Moreover, fourth active vector generator 3723 communicating a “θ+180°” phase shifted signal, if combined with a “Θ” phase angle signal from second active vector generator 3721, results in the second transmit beam input being transmitted as a vertical slant polarized transmit beam output.
In accordance with an exemplary embodiment and with reference to FIG. 38, independent polarization multi-beam receive architecture 3800 comprises active power splitters, active vector generators, active power combiners, and a radiating element 3801. These elements are configured to form multiple output beams from the signals received at radiating element 3801. In an exemplary embodiment, receive architecture 3800 forms independent polarized receive output beams. More specifically, in an exemplary embodiment, receive architecture 3800 forms N independent polarized receive output beams.
Each receive output beam, regardless of the polarization, is formed using a similar component configuration. In an exemplary embodiment, a signal is received at radiating element 3801 having a vertical beam signal component and a horizontal beam signal component. The vertical beam signal is communicated to a first active power splitter 3810 and the horizontal beam signal is communicated to a second active power splitter 3811. In an exemplary embodiment, first active power splitter 3810 is configured to divide the vertical beam signal into at least two signals, and second active power splitter 3811 is configured to divide the horizontal beam signal into at least two signals. Moreover, first active power splitter 3810 may be understood to comprise multiple active power splitters, and second active power splitter 3811 may be understood to comprise the same number of multiple active power splitters. In an exemplary embodiment, active power splitters 3810, 3811 individually divide the signal into two or more signals, such that the vertical beam signal and the horizontal beam signal are divided into a certain number of signals, for example N signals.
In an exemplary embodiment, each beam is formed using a first active vector generator 3820, a second active vector generator 3821, and an active power combiner 3830. The first active vector generator 3820 receives the vertical beam signal from first active power splitter 3810. Furthermore, second active vector generator 3821 receives the horizontal beam signal from second active power splitter 3811. In an exemplary embodiment, a digital control (not shown) communicates polarization and beam steering commands to first active vector generator 3820 and second active vector generator 3821. In accordance with an exemplary embodiment, active power combiner 3830 receives two intermediate signals, one signal from first active vector generator 3820 and another signal from second active vector generator 3821. Active power combiner 3830 combines the two signals into an output beam. The output beam can have any polarization, such as linear, circular, elliptical, or slant polarization, depending on the parameters of active vector generators 3820, 3821. For example, first active vector generator 3820 can generate a signal with a vertical beam with steering angle of “Θa.” The polarization of the output beam is dependent upon the difference in the beam steering angles of the two power combiner input signals. For example, and assuming the vertical beam maintains a steering angle of “Θa”: second active vector generator 3821 producing a horizontal beam with steering angle of “Θa” generates an output beam with horizontal slant polarization; a horizontal beam with steering angle of “Θa ±180°” generates an output beam with vertical slant polarization; a horizontal beam with steering angle of “Θa+90°” generates an output beam with right hand circular polarization (RHCP); a horizontal beam with steering angle of “Θa−90°” generates an output beam with left hand circular polarization (LHCP). In various exemplary embodiments, receive architecture 3800 is configured to provide complete polarization flexibility between horizontal and vertical polarization on a beam by beam basis. In various embodiments, receive architecture 3800 uses 2*N active vector generators to accomplish this flexibility. Signal outputs of N number of first active vector generators 3820 and N number of second active vector generators 3821 are combined at N number of active power combiners 3830 to form N receive beam outputs.
In accordance with an exemplary embodiment and with reference to FIG. 39, independent-polarization multi-beam transmit architecture 3900 comprises active power splitters, active vector generators, and active power combiners in communication with a radiating element 3901 to form an independent polarized transmit signal from multiple transmit input beams. In an exemplary embodiment, transmit architecture 3900 generates an independent-polarized transmit signal from two or more input beams, which can have any polarization such as linear, circular, elliptical, or slant polarization. Furthermore, the transmit signal can have any polarization, such as linear, circular, elliptical, or slant polarization. More specifically, in an exemplary embodiment, transmit architecture 3900 inputs include N transmit input beams that are each individually one of horizontal or vertical input beams.
Each input beam, regardless of initial polarization and beam steering angle, is added to the independent polarized output signal using a similar component configuration. In an exemplary embodiment, an active power splitter 3910 receives an input beam and divides the input beam into two divided signals. A first active vector generator 3920 receives one of the two divided signals at the input. A second active vector generator 3921 receives the other of the two divided signals at the input. In an exemplary embodiment, a digital control (not shown) communicates polarization and beam steering commands to first active vector generator 3920 and second active vector generator 3921.
In an exemplary embodiment, a vertical output beam is formed using two separate first active vector generators 3920 and a first active power combiner 3930. One of the first active vector generators 3920 receives a split signal from an active power splitter 3910 and the other of the first active vector generators 3920 receives a split signal from another active power splitter 3910.
In various embodiments, one of the first active vector generators 3920 communicates a first vertical beam signal having a beam steering angle of “Θa” to first active power combiner 3930. Further, the other of the first active vector generators 3920 communicates a second vertical beam signal to first active power combiner 3930. The beam steering angle of the second vertical output beam is set based on the desired polarization of the vertical output beam. In accordance with an exemplary embodiment, first active power combiner 3930 receives two input signals, the first vertical beam signal from one first active vector generator 3920 and the second vertical beam signal from another first active vector generator 3920. First active power combiner 3930 combines the two signals into the vertical output beam. The vertical beam can be any polarization type, including linear, circular, elliptical, or slant polarization, depending on the parameters of the first active vector generators 3920. For example, and assuming the vertical beam maintains a steering angle of “Θa”: a second vertical beam steering angle of “Θa” generates a vertical output beam with horizontal slant polarization; a second vertical beam steering angle of “Θa ±180°” generates a vertical output beam with vertical slant polarization; a second vertical beam steering angle of “Θa+90°” generates a vertical output beam with right hand circular polarization (RHCP); a second vertical beam steering angle of “Θa −90°” generates a vertical output beam with left hand circular polarization (LHCP).
Moreover, in various exemplary embodiments, a horizontal output beam is formed using two separate second active vector generators 3921 and the second active power combiner 3931. One of the second active vector generators 3921 receives a split signal from an active power splitter 3910 and the other of the second active vector generators 3921 receives a split signal from another active power splitter 3910.
In various embodiments, one of the second active vector generators 3921 communicates a first horizontal beam signal having a beam steering angle of “Θb” to second active power combiner 3931. Further, the other of the second active vector generators 3921 communicates a second horizontal beam signal to second active power combiner 3931. The beam steering angle of the second horizontal output beam is set based on the desired polarization of the horizontal output beam. In accordance with an exemplary embodiment, second active power combiner 3931 receives two input signals, the first horizontal beam signal from one of second active vector generator 3921 and the second horizontal beam signal from another second active vector generator 3921. Second active power combiner 3931 combines the two signals into the horizontal output beam. The horizontal beam can be any polarization type, including linear, circular, elliptical, or slant polarization, depending on the parameters of the second active vector generators 3921. For example: a second horizontal beam steering angle of “Θb” generates a horizontal output beam with horizontal slant polarization; a second horizontal beam steering angle of “Θb±180°” generates a horizontal output beam with vertical slant polarization; a second horizontal beam steering angle of “Θb+90°” generates a horizontal output beam with right hand circular polarization (RHCP); a second horizontal beam steering angle of “Θb−90°” generates a horizontal output beam with left hand circular polarization (LHCP).
First active power combiner 3930 may be understood to comprise multiple active power combiners, and second active power combiner 3931 may be understood to comprise the same number of multiple active power combiners. As would be known to one skilled in the art in light of the disclosure, the order of signal combination within first active power combiner 3930 and the order of signal combination within second active power combiner 3931 is irrelevant. In accordance with the various embodiments, the transmit vertical beam is a combination of the signal outputs from all the first active vector generators (ΣVG11-N) and the transmit horizontal beam is a combination of the signal outputs from all the second active vector generators (ΣVG21-N). In an exemplary embodiment, transmit architecture 3900 is configured to provide complete polarization flexibility on a beam by beam basis. However, transmit architecture 3900 uses 2*N active vector generators to accomplish this complete flexibility. For example, FIG. 39 illustrates an embodiment with N=4.
In accordance with an exemplary embodiment, and with reference to FIG. 40, a phased array integrated circuit (“IC”) 4000 is configured as a 2-beam, 4-radiating element receiver. The phased array IC 4000 comprises a first subcircuit 4010 in communication with a first radiating element 4011, a second subcircuit 4020 in communication with a second radiating element 4021, a third subcircuit 4030 in communication with a third radiating element 4031, and a fourth subcircuit 4040 in communication with a fourth radiating element 4041. Each subcircuit 4010, 4020, 4030, 4040 receives a pair of spatially orthogonal RF signals from the respectively coupled radiating element 4011, 4021, 4031, 4041 and generates two receive beam output signals, one for each beam to be formed. In various embodiments, the pair of spatially orthogonal RF signals received from the various radiating elements 4011, 4021, 4031, 4041 can have any polarization. In other words, the signals received from radiating element 4011 can be a first polarization, for example LHCP, and the signals received from radiating element 4021 can be a second polarization, for example vertical polarization. Furthermore, the two receive beam output signals can also have different polarizations. For example, a first receive beam output signal can be RHCP and a second receive beam output signal can be horizontal polarization. In other words, phased array integrated circuit 4000 can be configured in an exemplary embodiment to receive four input signals of any polarization on four separate radiating elements, and generate two receive output signals, with each receive output signal being controllable for independent polarization.
The structure and function of each subcircuit 4010, 4020, 4030, 4040 is substantially similar. Thus, only first subcircuit 4010 will be discussed in detail. In accordance with various embodiments, first subcircuit 4010 comprises a first active power splitter 4016 and a second active power splitter 4017 in communication with a radiating element 4011. First subcircuit 4010 further comprises a first active vector generator 4012 in parallel with a second active vector generator 4013, which are both in communication with active power splitter 4016. Moreover, first subcircuit 4010 further comprises a third active vector generator 4014 in parallel with a fourth active vector generator 4015, which are both in communication with active power splitter 4017. Additionally, first subcircuit 4010 further comprises a first active power combiner 4018 and a second active power combiner 4019. First active power combiner 4018 is in communication with first active vector generator 4012 and third active vector generator 4014. Second active power combiner 4019 is in communication with second active vector generator 4013 and fourth active vector generator 4015. In an exemplary embodiment, a digital control (not shown) communicates polarization and beam steering commands to active vector generators 4012, 4013, 4014, 4015. The operation of first subcircuit 4010 is similar to the operation of receive phased array antenna 3600, and additional understanding of first subcircuit 4010 is provided by referring to the description of receive phased array antenna 3600.
In accordance with an exemplary embodiment, a first receive beam output is generated by combining one of the two output signals from each of four subcircuits 4010, 4020, 4030, 4040. A second receive beam output is generated by combining the second of the two output signals from each of four subcircuits 4010, 4020, 4030, 4040. In an exemplary embodiment, multiple combiners are used to combine the subcircuit output signals into a first receive beam output and a second receive beam output.
In a more specific exemplary embodiment, an active combiner 4051 is configured to combine the first of the two outputs from first and second subcircuits 4010, 4020. Furthermore, an active combiner 4061 is configured to combine the second of the two outputs from first and second subcircuits 4010, 4020. Also in the exemplary embodiment, an active combiner 4052 is configured to combine the first of the two outputs from third and fourth subcircuits 4030, 4040. An active combiner 4062 is configured to combine the second of the two outputs from third and fourth subcircuits 4030, 4040. At the next stage, an active combiner 4053 is configured to combine the combined outputs of active combiners 4051 and 4052 to form a first receive beam output. Furthermore, an active combiner 4063 is configured to combine the combined outputs of active combiners 4061 and 4062 to form a second receive beam output.
In addition to a 2-beam, 4-radiating element receiver, a similar structure may be configured as a 2-beam, 4-radiating element transmitter. In an exemplary embodiment, and with reference to FIG. 41, a phased array integrated circuit 4100 is configured as a 2-beam, 4-radiating element transmitter. The phased array IC 4100 comprises a first subcircuit 4110 in communication with a first radiating element 4111, a second subcircuit 4120 in communication with a second radiating element 4121, a third subcircuit 4130 in communication with a third radiating element 4131, and a fourth subcircuit 4140 in communication with a fourth radiating element 4141. Each subcircuit 4110, 4120, 4130, 4140 receives two input signals and transmits signals to the spatially orthogonal ports of the respectively coupled radiating element 4111, 4121, 4131, 4141. In various embodiments, the pair of spatially orthogonal RF signals transmitted to the various radiating elements 4111, 4121, 4131, 4141 can have any polarization. In other words, the signals transmitted to radiating element 4011 can be a first polarization, for example LHCP, and the signals transmitted to radiating element 4021 can be a second polarization, for example vertical polarization. Furthermore, the two transmit beam input signals can also have different polarizations. For example, a first transmit beam input signal can be RHCP and a second transmit beam input signal can be horizontal polarization. In other words, phased array integrated circuit 4100 can be configured in an exemplary embodiment to receive two transmit beam input signals of any polarization and generate output signals on four separate radiating elements, with each output signal being controllable for independent polarization.
In accordance with an exemplary embodiment, a first transmit beam and a second transmit beam are provided to phased array IC 4100. In an exemplary embodiment, multiple splitters are used to divide the first and second transmit beams that are communicated to each of four subcircuits 4110, 4120, 4130, 4140 as input signals.
In a more specific exemplary embodiment, an active splitter 4153 is configured to divide the first transmit beam input into two separate signals that are communicated to an active splitter 4151 and an active splitter 4152, respectively. Similarly, an active splitter 4163 is configured to divide the second transmit beam input into two separate signals that are communicated to an active splitter 4161 and an active splitter 4162, respectively. At the next stage, active splitters 4151, 4161 are configured to divide the communicated signals and communicate the divided signals to first subcircuit 4110 and second subcircuit 4120. The active splitters 4152, 4162 are configured to divide the communicated signals and communicate the divided signals to third sub circuit 4130 and fourth sub circuit 4140.
The structure and function of each subcircuit 4110, 4120, 4130, 4140 is substantially similar. Thus, only first subcircuit 4110 will be discussed in detail. In accordance with an exemplary embodiment, first subcircuit 4110 comprises a first active power splitter 4118 and a second active power splitter 4119, which are configured to individually receive an input signal from active splitters 4151, 4161, respectively. First subcircuit 4110 further comprises a first active vector generator 4114 in parallel with a second active vector generator 4115, and also comprises a third active vector generator 4116 in parallel with a fourth active vector generator 4117. In various embodiments, first active vector generator 4114 and third active vector generator 4116 are both in communication with first active power splitter 4118. Moreover, second active vector generator 4115 and fourth active vector generator 4117 are both in communication with second active power splitter 4119. Additionally, first subcircuit 4110 further comprises a first active power combiner 4112 and a second active power combiner 4113. First active power combiner 4112 is in communication with first active vector generator 4114 and second active vector generator 4115. Second active power combiner 4113 is in communication with third active vector generator 4116 and fourth active vector generator 4117. In an exemplary embodiment, a digital controller (not shown) communicates polarization and beam steering commands to active vector generators 4114, 4115, 4116, 4117. The operation of first subcircuit 4110 is similar to the operation of transmit phased array antenna 3700, and additional understanding of first subcircuit 4110 is provided by referring to the description of receive phased array antenna 3700.
In an exemplary embodiment, a first transmit beam input is received at first active power splitter 4118 from active splitter 4151 and a second transmit input beam is received at second active power splitter 4119 from active splitter 4161. In an exemplary embodiment, first active power splitter 4118 is configured to divide the first transmit beam input into two signals, and second active power splitter 4119 is configured to divide the second transmit input beam into two signals.
In an exemplary embodiment and with reference to FIG. 42A, a phased array integrated circuit 4200 is configured as a 4-beam, 4-radiating element receiver. The phased array IC 4200 comprises a first subcircuit 4210 in communication with a first radiating element 4211, a second subcircuit 4220 in communication with a second radiating element 4221, a third subcircuit 4230 in communication with a third radiating element 4231, and a fourth subcircuit 4240 in communication with a fourth radiating element 4241. Each subcircuit 4210, 4220, 4230, 4240 receives a pair of spatially orthogonal RF signals from the respectively coupled radiating element 4211, 4221, 4231, 4241 and generates four output signals, one for each beam to be formed.
The structure and function of each subcircuit 4210, 4220, 4230, 4240 is substantially similar. Thus, only first subcircuit 4210 will be discussed in detail. In accordance with an exemplary embodiment and with reference to FIG. 42B, first subcircuit 4210, in communication with radiating element 4211, comprises a first set of active splitters 4212A, 4212B, 4212C and a second set of active splitters 4213A, 4213B, 4213C. In various embodiments, first subcircuit 4210 further comprises a first set of active vector generators 4214A, 4214B, 4214C, 4214D and a second set of active vector generators 4215A, 4215B, 4215C, 4215D. In an exemplary embodiment, a digital control (not shown) communicates polarization and beam steering commands to the first set of active vector generators 4214A, 4214B, 4214C, 4214D and the second set of active vector generators 4215A, 4215B, 4215C, 4215D. Additionally, first subcircuit 4210 comprises a set of active power combiners 4216A, 4216B, 4216C, 4216D that can be configured to output four intermediate signals for further processing in phased array integrated circuit 4200.
The first set of active splitters 4212A, 4212B, 4212C receives a vertical beam signal from radiating element 4211. The first set of active splitters 4212A, 4212B, 4212C divides the vertical beam signal into four intermediate vertical beam signals for transmitting to the first set of active vector generators 4214A, 4214B, 4214C, 4214D. One intermediate vertical beam signal is communicated to each one of the first set of active vector generators 4214A, 4214B, 4214C, 4214D.
Similarly, the second set of active splitters 4213A, 4213B, 4213C, 4213D receives a horizontal beam signal from radiating element 4211. The second set of active splitters 4213A, 4213B, 4213C, 4213D divides the horizontal beam signal into four intermediate horizontal beam signals for transmitting to the second set of active vector generators 4215A, 4215B, 4215C, 4215D. One intermediate horizontal beam signal is communicated to each one of the second set of active vector generators 4215A, 4215B, 4215C, 4215D.
The formation of the signals combined by active power combiners 4216A, 4216B, 4216C, 4216D are similar in nature and operation, and therefore only the signal formation at active power combiner 4216A will be described in detail. In various embodiments, active power combiner 4216A receives a first feed signal from active vector generator 4214A and a second feed signal from active vector generator 4215A. The combined signal formed by active power combiner 4216A can be any polarization, including linear, circular, elliptical, or slant polarization, depending on relative phases of the vertical output beam and the horizontal output beam. The first feed signal can be communicated with a phase angle of “Θ” in response to passing through active vector generator 4214A and the second feed signal can be communicated with a phase angle of “Θ,” “Θ+90°,” “Θ−90°,” or “Θ±180°” in response to passing through active vector generator 4215A. The polarization of the combined signal is based on the parameters of active vector generator 4214A and the parameters of active vector generator 4215A.
For example, active vector generator 4215A communicating a “Θ” phase angle signal, if combined with a “Θ” phase angle signal from active vector generator 4214A, results in active power combiner 4216A generating a horizontal slant polarized first receive beam output. Additionally, active vector generator 4215A communicating a “Θ+90°” phase angle signal, if combined with a “Θ” phase angle signal from active vector generator 4214A, results in active power combiner 4216A generating a right hand circular polarized (RHCP) first receive beam output. Further, active vector generator 4215A communicating a “Θ−90°” phase angle signal, if combined with a “Θ” phase angle signal from active vector generator 4214A, results in active power combiner 4216A generating a left hand circular polarized (LHCP) first receive beam output. Moreover, active vector generator 4215A communicating a “Θ±180°” phase shifted signal, if combined with a “Θ” phase angle signal from active vector generator 4214A, results in active power combiner 4216A generating a vertical slant polarized first receive beam output.
Similarly, active power combiner 4216B receives signals from active vector generator 4214B and 4215B, active power combiner 4216C receives signals from active vector generator 4214C and 4215C, and active power combiner 4216D receives signals from active vector generator 4214D and 4215D. Further, each active power combiner 4216B, 4216C, 4216D individually outputs a signal with a polarization that depends on the parameters of the respective pairs of active vector generators.
In various exemplary embodiments, first subcircuit 4210 is configured to provide complete polarization flexibility on a beam by beam basis. In an exemplary embodiment, a digital control (not shown) communicates polarization and beam steering commands to the first and second sets of active vector generators.
In accordance with an exemplary embodiment, a first receive beam output is generated by combining one of the four output signals from each of four subcircuits 4210, 4220, 4230, 4240. A second receive beam output is generated by combining a second of the four output signals from each of four subcircuits 4210, 4220, 4230, 4240. A third receive beam output is generated by combining a third of the four output signals from each of four subcircuits 4210, 4220, 4230, 4240. A fourth receive beam output is generated by combining a fourth of the four output signals from each of four subcircuits 4210, 4220, 4230, 4240. In an exemplary embodiment, multiple combiners are used to combine the subcircuit output signals into the four receive beam outputs.
In a more specific exemplary embodiment, an active combiner 4251 is configured to combine the first of the four outputs from first and second subcircuits 4210, 4220. Furthermore, an active combiner 4261 is configured to combine the second of the four outputs from first and second subcircuits 4210, 4220. Likewise, an active combiner 4271 is configured to combine the third of the four outputs from first and second subcircuits 4210, 4220. An active combiner 4281 is configured to combine the fourth of the four outputs from first and second subcircuits 4210, 4220.
Also in the exemplary embodiment, an active combiner 4252 is configured to combine the first of the two outputs from third and fourth subcircuits 4230, 4240. An active combiner 4262 is configured to combine the second of the four outputs from third and fourth subcircuits 4230, 4240. Furthermore, an active combiner 4272 is configured to combine the third of the four outputs from third and fourth subcircuits 4230, 4240. An active combiner 4282 is configured to combine the fourth of the four outputs from third and fourth subcircuits 4230, 4240.
At the next stage, an active combiner 4253 is configured to combine the combined outputs of active combiners 4251, 4252 to form a first receive beam output. An active combiner 4263 is configured to combine the combined outputs of active combiners 4261, 4262 to form a second receive beam output. Furthermore, an active combiner 4273 is configured to combine the combined outputs of active combiners 4271, 4272 to form a third receive beam output. An active combiner 4283 is configured to combine the combined outputs of active combiners 4281, 4282 to form a fourth receive beam output.
In an exemplary embodiment, and with reference to FIGS. 43A and 43B, a phased array integrated circuit 4300 is configured as a 4-beam, 4-radiating element transmitter. The phased array IC 4300 comprises a first subcircuit 4310 in communication with a first radiating element 4311, a second subcircuit 4320 in communication with a second radiating element 4321, a third subcircuit 4330 in communication with a third radiating element 4331, and a fourth subcircuit 4340 in communication with a fourth radiating element 4341. Each subcircuit 4310, 4320, 4330, 4340 receives four input signals and transmits RF signals to the spatially orthogonal ports of the respectively coupled radiating element 4311, 4321, 4331, 4341.
In accordance with an exemplary embodiment, a first, second, third, and fourth transmit beam are provided to phased array IC 4300. In an exemplary embodiment, multiple splitters are used to divide the first, second, third, and fourth transmit beams that are communicated to each of four subcircuits 4310, 4320, 4330, 4340 as input signals.
In a more specific exemplary embodiment, an active splitter 4353 is configured to divide the first transmit beam input into two separate signals that are communicated to an active splitter 4351 and an active splitter 4352, respectively. Similarly, an active splitter 4363 is configured to divide the second transmit beam input into two separate signals that are communicated to an active splitter 4361 and an active splitter 4362, respectively. In an exemplary embodiment, an active splitter 4373 is configured to divide the third transmit beam input into two separate signals that are communicated to an active splitter 4371 and an active splitter 4372, respectively. Furthermore, an active splitter 4383 is configured to divide the fourth transmit beam input into two separate signals that are communicated to an active splitter 4381 and an active splitter 4382, respectively.
At the next stage, active splitters 4351, 4361, 4371, 4381 are configured to divide the communicated signals and communicate the divided signals to first subcircuit 4310 and second subcircuit 4320. The active splitters 4352, 4362, 4372, 4382 are configured to divide the communicated signals and communicate the divided signals to third subcircuit 4330 and fourth subcircuit 4340.
The structure and function of each subcircuit 4310, 4320, 4330, 4340 is substantially similar. Thus, only first subcircuit 4310 will be discussed in detail. In accordance with an exemplary embodiment and with reference to FIG. 43B, first subcircuit 4310, in communication with radiating element 4311, comprises a first set of active power combiners 4312A, 4312B, 4312C and a second set of active power combiners 4313A, 4313B, 4313C. In various embodiments, first subcircuit 4310 further comprises a first set of active vector generators 4314A, 4314B, 4314C, 4314D and a second set of active vector generators 4315A, 4315B, 4315C, 4315D. In an exemplary embodiment, a digital control (not shown) communicates polarization and beam steering commands to the first set of active vector generators 4314A, 4314B, 4314C, 4314D and the second set of active vector generators 4315A, 4315B, 4315C, 4315D. Additionally, first subcircuit 4310 comprises a set of active power splitters 4316A, 4316B, 4316C, 4316D that can be configured to receive four input beam signals for further processing in phased array integrated circuit 4300.
In various embodiments, the active power splitters 4316A, 4316B, 4316C, 4316D each receive a divided transmit beam input, and are each in communication with two active vector generators. The operation of the active power splitters and active vector generators receiving the four input beam signals are similar in nature and operation, and therefore only a single grouping of a power splitter and active vector generators will be described in detail.
In an exemplary embodiment, active power splitter 4316A is configured to divide a first transmit beam input into a first pair of feed signals. One of the pair of feed signals is communicated to active vector generator 4314A and the other intermediate signal is communicated to active vector generator 4315A. Each of active vector generators 4314A, 4315A is configured to phase shift the respective feed signal to generate a phase shifted signal with a desired polarization. The specific phase shift is dependent upon the polarization of the first input beam and the polarization of the desired phase shifted signal. In order to transmit a cohesive signal from radiating element 4311, the polarization of the desired phase shifted signal is the same for both the first and second sets of active vector generators.
In various embodiments, active vector generator 4314A communicates a first vertical beam signal having a beam steering angle of “Θa” to a combiner, such as first set of active power combiners 4312A, 4312B, 4312C. In accordance with an exemplary embodiment, first set of active power combiners 4312A, 4312B, 4312C receives a plurality of input signals, such as from the first set of active vector generators 4314A, 4314B, 4314C, 4314D. The plurality of inputs signals are already appropriately phase shifted based on the desired polarization. The desired polarization can include linear, circular, elliptical, or slant polarization, depending on the parameters of active vector generator 4314A and the parameters of active vector generator 4315A. In various embodiments, the first set of active power combiners may combine the plurality of input signals in any order as would be understood by one skilled in the art based on the disclosure. The plurality of input signals are combined in a single a vertical output beam.
Similarly, in various embodiments, active vector generator 4315A communicates a first horizontal beam signal to a combiner, such as second set of active power combiners 4313A, 4313B, 4313C. The beam steering angle of the first horizontal output beam is set based on the desired polarization of the phased shifted signal. In accordance with an exemplary embodiment, second set of active power combiners 4313A, 4313B, 4313C receives a plurality of input signals, such as from the second set of active vector generators 4315A, 4315B, 4315C, 4315D. The plurality of inputs signals are already appropriately phase shifted based on the desired polarization. In various embodiments, the second set of active power combiners may combine the plurality of input signals in any order as would be understood by one skilled in the art based on the disclosure. The plurality of input signals are combined in a single a horizontal output beam.
In accordance with various embodiments, the vertical output beam and the horizontal output beam can be transmitted via radiating element 4311 as a transmit beam output. The transmit beam output can be any polarization type, including linear, circular, elliptical, or slant polarization, depending on relative phases of the vertical output beam and the horizontal output beam. As previously described, the relative phases of the vertical output beam and the horizontal output beam are based on the parameters of first active vector generators 4314A, 4314B, 4314C, 4314D and the parameters of second active vector generators 4315A, 4315B, 4315C, 4315D. For example, active vector generator 4315A communicating a “Θ” phase angle signal, if combined with a “Θ” phase angle signal from active vector generator 4314A, results in the first transmit beam being transmitted as a horizontal slant polarized transmit beam output. Additionally, active vector generator 4315A communicating a “Θ+90°” phase angle signal, if combined with a “Θ” phase angle signal from active vector generator 4314A, results in the first transmit beam being transmitted as a RHCP transmit beam output. Further, active vector generator 4315A communicating a “Θ−90°” phase angle signal, if combined with a “Θ” phase angle signal from active vector generator 4314A, results in the first transmit beam being transmitted as a LHCP transmit beam output. Moreover, active vector generator 4315A communicating a “Θ+180°” phase shifted signal, if combined with a “Θ” phase angle signal from active vector generator 4314A, results in the first transmit beam input being transmitted as a vertical slant polarized transmit beam output.
In various exemplary embodiments, first subcircuit 4310 is configured to provide complete polarization flexibility on a beam by beam basis. In an exemplary embodiment, a digital control (not shown) communicates polarization and beam steering commands to the first and second sets of active vector generators.
In an exemplary embodiment, software reconfiguration of the active vector generators occurs in real-time as the system is operating, which enables a phased array antenna to have the capabilities previously described. Additionally, in the exemplary embodiment, there are no hardware changes that require physical and/or manual operations for polarization changing or system alterations. In other words, in an exemplary embodiment, the phased array antenna is fully electronically adjusted, which results in greater degrees of freedom compared to typical systems. Furthermore, the dynamic control of signal polarization of a phased array antenna has numerous applications.
In one application embodiment, dynamic control of signal polarization is implemented for secure communications by utilizing polarization hopping. Communication security can be enhanced by changing the polarization of a communications signal at a rate known to other authorized users. An unauthorized user will not know the correct polarization for any given instant and if using a constant polarization, the unauthorized user would only have the correct polarization for brief instances in time. A similar application to polarization hopping for secure communications is to use polarization hopping for signal scanning. In other words, the polarization of the antenna can be continuously adjusted to monitor for signal detection.
In an exemplary embodiment, dynamic control of signal polarization facilitates radar target identification using a single antenna. Radar target identification systems use information from multiple polarizations to provide increased target identification information. Additionally, a reflected signal's polarization and signal strength can be changed by the object off which it reflects. Thus, in an exemplary embodiment, a single antenna is configured to receive multiple polarizations and produce better identification due to acquiring more information about the target.
4 Color System:
In the field of consumer satellite RF communication, a satellite will typically transmit and/or receive data (e.g., movies and other television programming, internet data, and/or the like) to consumers who have personal satellite dishes at their home. More recently, the satellites may transmit/receive data from more mobile platforms (such as, transceivers attached to airplanes, trains, and/or automobiles). It is anticipated that increased use of handheld or portable satellite transceivers will be the norm in the future. Although sometimes described in this document in connection with home satellite transceivers, the prior art limitations now discussed may be applicable to any personal consumer terrestrial transceivers (or transmitters or receivers) that communicate with a satellite.
A propagating radio frequency (RF) signal can have different polarizations, namely linear, elliptical, or circular. Linear polarization consists of vertical polarization and horizontal polarization, whereas circular polarization consists of left-hand circular polarization (LHCP) and right-hand circular polarization (RHCP). An antenna is typically configured to pass one polarization, such as LHCP, and reject the other polarization, such as RHCP.
Also, conventional very small aperture terminal (VSAT) antennas utilize a fixed polarization that is hardware dependent. The basis polarization is generally set during installation of the satellite terminal, at which point the manual configuration of the polarizer hardware is fixed. For example, a polarizer is generally set for LHCP or RHCP and fastened into position. To change polarization in a conventional VSAT antenna might require unfastening the polarizer, rotating it 90° to the opposite circular polarization, and then refastening the polarizer. Clearly this could not be done with much frequency and only a limited number (on the order of 5 or maybe 10) of transceivers could be switched per technician in a given day.
Unlike a typical single polarization antenna, some devices are configured to change polarizations without disassembling the antenna terminal. As an example, a prior embodiment is the use of “baseball” switches to provide electronically commandable switching between polarizations. The rotation of the “baseball” switches causes a change in polarization by connecting one signal path and terminating the other signal path. However, each “baseball” switch requires a separate rotational actuator with independent control circuitry, which increases the cost of device such that this configuration is not used (if at all) in consumer broadband or VSAT terminals, but is instead used for large ground stations with a limited number of terminals.
Furthermore, another approach is to have a system with duplicate hardware for each polarization. The polarization selection is achieved by completing or enabling the path of the desired signal and deselecting the undesired signal. This approach is often used in receive-only terminals, for example satellite television receivers having low-cost hardware. However, with two way terminals that both transmit and receive such as VSAT or broadband terminals, doubling the hardware greatly increases the cost of the terminal.
Conventional satellites may communicate with the terrestrial based transceivers via radio frequency signals at a particular frequency band and a particular polarization. Each combination of a frequency band and polarization is known as a “color.” The satellite will transmit to a local geographic area with signals in a “beam” and the geographic area that can access signals on that beam may be represented by “spots” on a map. Each beam/spot will have an associated “color.” Thus, beams of different colors will not have the same frequency, the same polarization, or both.
In practice, there is some overlap between adjacent spots, such that at any particular point there may be two, three, or more beams that are “visible” to any one terrestrial transceiver. Adjacent spots will typically have different “colors” to reduce noise/interference from adjacent beams.
In the prior art, broadband consumer satellite transceivers are typically set to one color and left at that setting for the life of the transceiver. Should the color of the signal transmitted from the satellite be changed, all of the terrestrial transceivers that were communicating with that satellite on that color would be immediately stranded or cut off. Typically, a technician would have to visit the consumer's home and manually change out (or possibly physically disassemble and re-assemble) the transceiver or polarizer to make the consumer's terrestrial transceiver once again be able to communicate with the satellite on the new “color” signal. The practical effect of this is that in the prior art, no changes are made to the signal color transmitted from the satellite.
For similar reasons, a second practical limitation is that terrestrial transceivers are typically not changed from one color to another (i.e., if they are changed, it is a manual process). Thus, there is a need for a new low cost method and device to remotely change the frequency and/or polarization of an antenna system. There is also a need for a method and device that may be changed nearly instantaneously and often.
In spot beam communication satellite systems, both frequency and polarization diversity are utilized to reduce interference from adjacent spot beams. In an exemplary embodiment, both frequencies and polarizations are re-used in other beams that are geographically separated to maximize communications traffic capacity. The spot beam patterns are generally identified on a map using different colors to identify the combination of frequency and polarity used in that spot beam. The frequency and polarity re-use pattern is then defined by how many different combinations (or “colors”) are used.
In accordance with various exemplary embodiments and with reference to FIG. 28, an antenna system is configured for frequency and polarization switching. In one specific exemplary embodiment, the frequency and polarization switching comprises switching between two frequency ranges and between two different polarizations. This may be known as four color switching. In other exemplary embodiments, the frequency and polarization switching comprises switching between three frequency ranges and between two different polarizations, for a total of six separate colors. Furthermore, in various exemplary embodiments, the frequency and polarization switching may comprise switching between two polarizations with any suitable number of frequency ranges. In another exemplary embodiment, the frequency and polarization switching may comprise switching between more than two polarizations with any suitable number of frequency ranges.
In accordance with various exemplary embodiments, the ability to perform frequency and polarization switching has many benefits in terrestrial microwave communications terminals. For example, doing so may facilitate increased bandwidth, load shifting, roaming, increased data rate/download speeds, improved overall efficiency of a group of users on the system, or improved individual data communication rates. Terrestrial microwave communications terminals, in one exemplary embodiment, comprise point to point terminals. In another exemplary embodiment, terrestrial microwave communications terminals comprise ground terminals for use in communication with any satellite, such as a satellite configured to switch frequency range and/or polarity of a RF signal broadcasted. These terrestrial microwave communications terminals are spot beam based systems.
In accordance with various exemplary embodiments, a satellite configured to communicate one or more RF signal beams each associated with a spot and/or color has many benefits in microwave communications systems. For example, similar to what was stated above for exemplary terminals in accordance with various embodiments, doing so may facilitate increased bandwidth, load shifting, roaming, increased data rate/download speeds, improved overall efficiency of a group of users on the system, or improved individual data communication rates. In accordance with another exemplary embodiment, the satellite is configured to remotely switch frequency range and/or polarity of a RF signal broadcasted by the satellite. This has many benefits in microwave communications systems. In another exemplary embodiment, satellites are in communications with any suitable terrestrial microwave communications terminal, such as a terminal having the ability to perform frequency and/or polarization switching.
Prior art spot beam based systems use frequency and polarization diversity to reduce or eliminate interference from adjacent spot beams. This allows frequency reuse in non-adjacent beams resulting in increased satellite capacity and throughput. Unfortunately, in the prior art, in order to have such diversity, installers of such systems must be able to set the correct polarity at installation or carry different polarity versions of the terminal. For example, at an installation site, an installer might carry a first terminal configured for left hand polarization and a second terminal configured for right hand polarization and use the first terminal in one geographic area and the second terminal in another geographic area. Alternatively, the installer might be able to disassemble and reassemble a terminal to switch it from one polarization to another polarization. This might be done, for example, by removing the polarizer, rotating it 90°, and reinstalling the polarizer in this new orientation. These prior art solutions are cumbersome in that it is not desirable to have to carry a variety of components at the installation site. Also, the manual disassembly/reassembly steps introduce the possibility of human error and/or defects.
These prior art solutions, moreover, for all practical purposes, permanently set the frequency range and polarization for a particular terminal. This is so because any change to the frequency range and polarization will involve the time and expense of a service call. An installer would have to visit the physical location and change the polarization either by using the disassembly/re-assembly technique or by just switching out the entire terminal. In the consumer broadband satellite terminal market, the cost of the service call can exceed the cost of the equipment and in general manually changing polarity in such terminals is economically unfeasible.
In accordance with various exemplary embodiments, a low cost system and method for electronically or electro-mechanically switching frequency ranges and/or polarity is provided. In an exemplary embodiment, the frequency range and/or polarization of a terminal can be changed without a human touching the terminal. Stated another way, the frequency range and/or polarization of a terminal can be changed without a service call. In an exemplary embodiment, the system is configured to remotely cause the frequency range and/or polarity of the terminal to change.
In one exemplary embodiment, the system and method facilitate installing a single type of terminal that is capable of being electronically set to a desired frequency range from among two or more frequency ranges. Some exemplary frequency ranges include receiving 10.7 GHz to 12.75 GHz, transmitting 13.75 GHz to 14.5 GHz, receiving 18.3 GHz to 20.2 GHz, and transmitting 28.1 GHz to 30.0 GHz. Furthermore, other desired frequency ranges of a point-to-point system fall within 15 GHz to 38 GHz. In another exemplary embodiment, the system and method facilitate installing a single type of terminal that is capable of being electronically set to a desired polarity from among two or more polarities. The polarities may comprise, for example, left hand circular, right hand circular, vertical linear, horizontal linear, or any other orthogonal polarization. Moreover, in various exemplary embodiments, a single type of terminal may be installed that is capable of electronically selecting both the frequency range and the polarity of the terminal from among choices of frequency range and polarity, respectively.
In an exemplary embodiment, transmit and receive signals are paired so that a common switching mechanism switches both signals simultaneously. For example, one “color” may be a receive signal in the frequency range of 19.7 GHz to 20.2 GHz using RHCP, and a transmit signal in the frequency range of 29.5 GHz to 30.0 GHz using LHCP. Another “color” may use the same frequency ranges but transmit using RHCP and receive using LHCP. Accordingly, in an exemplary embodiment, transmit and receive signals are operated at opposite polarizations. However, in some exemplary embodiments, transmit and receive signals are operated on the same polarization which increases the signal isolation requirements for self-interference free operation.
Thus, a single terminal type may be installed that can be configured in a first manner for a first geographical area and in a second manner for a second geographical area that is different from the first area, where the first geographical area uses a first color and the second geographical area uses a second color different from the first color.
In accordance with an exemplary embodiment, a terminal, such as a terrestrial microwave communications terminal, may be configured to facilitate load balancing. In accordance with another exemplary embodiment, a satellite may be configured to facilitate load balancing. Load balancing involves moving some of the load on a particular satellite, or point-to-point system, from one polarity/frequency range “color” or “beam” to another. In an exemplary embodiment, the load balancing is enabled by the ability to remotely switch frequency range and/or polarity of either the terminal or the satellite.
Thus, in exemplary embodiments, a method of load balancing comprises the steps of remotely switching frequency range and/or polarity of one or more terrestrial microwave communications terminals. For example, system operators or load monitoring computers may determine that dynamic changes in system bandwidth resources has created a situation where it would be advantageous to move certain users to adjacent beams that may be less congested. In one example, those users may be moved back at a later time as the loading changes again. In an exemplary embodiment, this signal switching (and therefore this satellite capacity “load balancing”) can be performed periodically. In other exemplary embodiments, load balancing can be performed on many terminals (e.g., hundreds or thousands of terminals) simultaneously or substantially simultaneously. In other exemplary embodiments, load balancing can be performed on many terminals without the need for thousands of user terminals to be manually reconfigured.
In one exemplary embodiment, dynamic control of signal polarization is implemented for secure communications by utilizing polarization hopping. Communication security can be enhanced by changing the polarization of a communications signal at a rate known to other authorized users. An unauthorized user will not know the correct polarization for any given instant and if using a constant polarization, the unauthorized user would only have the correct polarization for brief instances in time. A similar application to polarization hopping for secure communications is to use polarization hopping for signal scanning. In other words, the polarization of the antenna can be continuously adjusted to monitor for signal detection.
In an exemplary embodiment, the load balancing is performed as frequently as necessary based on system loading. For example, load balancing could be done on a seasonal basis. For example, loads may change significantly when schools, colleges, and the like start and end their sessions. As another example, vacation seasons may give rise to significant load variations. For example, a particular geographic area may have a very high load of data traffic. This may be due to a higher than average population density in that area, a higher than average number of transceivers in that area, or a higher than average usage of data transmission in that area. In another example, load balancing is performed on an hourly basis. Furthermore, load balancing could be performed at any suitable time. In one example, if maximum usage is between 6-7 p.m. at night, then some of the users in the heaviest loaded beam areas could be switched to adjacent beams in a different time zone. In another example, if a geographic area comprises both office and home terminals, and the office terminals experience heaviest loads at different times than the home terminals, the load balancing may be performed between home and office terminals. In yet another embodiment, a particular area may have increased localized signal transmission traffic, such as related to high traffic within businesses, scientific research activities, graphic/video intensive entertainment data transmissions, a sporting event or a convention. Stated another way, in an exemplary embodiment, load balancing may be performed by switching the color of any subgroup(s) of a group of transceivers.
In an exemplary embodiment, the consumer broadband terrestrial terminal is configured to determine, based on preprogrammed instructions, what colors are available and switch to another color of operation. For example, the terrestrial terminal may have visibility to two or more beams (each of a different color). The terrestrial terminal may determine which of the two or more beams is better to connect to. This determination may be made based on any suitable factor. In one exemplary embodiment, the determination of which color to use is based on the data rate, the download speed, and/or the capacity on the beam associated with that color. In other exemplary embodiments, the determination is made randomly, or in any other suitable way.
This technique is useful in a geographically stationary embodiment because loads change over both short and long periods of time for a variety of reasons and such self adjusting of color selection facilitates load balancing. This technique is also useful in mobile satellite communication as a form of “roaming.” For example, in one exemplary embodiment, the broadband terrestrial terminal is configured to switch to another color of operation based on signal strength. This is, in contrast to traditional cell phone type roaming, where that roaming determination is based on signal strength. In contrast, here, the color distribution is based on capacity in the channel. Thus, in an exemplary embodiment, the determination of which color to use may be made to optimize communication speed as the terminal moves from one spot to another. Alternatively, in an exemplary embodiment, a color signal broadcast by the satellite may change or the spot beam may be moved and still, the broadband terrestrial terminal may be configured to automatically adjust to communicate on a different color (based, for example, on channel capacity).
In accordance with another exemplary embodiment, a satellite is configured to communicate one or more RF signal beams each associated with a spot and/or color. In accordance with another exemplary embodiment, the satellite is configured to remotely switch frequency range and/or polarity of a RF signal broadcasted by the satellite. In another exemplary embodiment, a satellite may be configured to broadcast additional colors. For example, an area and/or a satellite might only have 4 colors at a first time, but two additional colors, (making 6 total colors) might be dynamically added at a second time. In this event, it may be desirable to change the color of a particular spot to one of the new colors. With reference to FIG. 29A, spot 4 changes from “red” to then new color “yellow.” In one exemplary embodiment, the ability to add colors may be a function of the system's ability to operate, both transmit and/or receive over a wide bandwidth within one device and to tune the frequency of that device over that wide bandwidth.
In accordance with an exemplary embodiment, and with renewed reference to FIG. 28, a satellite may have a downlink, an uplink, and a coverage area. The coverage area may be comprised of smaller regions each corresponding to a spot beam to illuminate the respective region. Spot beams may be adjacent to one another and have overlapping regions. A satellite communications system has many parameters to work: (1) number of orthogonal time or frequency slots (defined as color patterns hereafter); (2) beam spacing (characterized by the beam roll-off at the cross-over point); (3) frequency re-use patterns (the re-use patterns can be regular in structures, where a uniformly distributed capacity is required); and (4) numbers of beams (a satellite with more beams will provide more system flexibility and better bandwidth efficiency). Polarization may be used as a quantity to define a re-use pattern in addition to time or frequency slots. In one exemplary embodiment, the spot beams may comprise a first spot beam and a second spot beam. The first spot beam may illuminate a first region within a geographic area, in order to send information to a first plurality of subscriber terminals. The second spot beam may illuminate a second region within the geographic area and adjacent to the first region, in order to send information to a second plurality of subscriber terminals. The first and second regions may overlap.
The first spot beam may have a first characteristic polarization. The second spot beam may have a second characteristic polarization that is orthogonal to the first polarization. The polarization orthogonality serves to provide an isolation quantity between adjacent beams. Polarization may be combined with frequency slots to achieve a higher degree of isolation between adjacent beams and their respective coverage areas. The subscriber terminals in the first beam may have a polarization that matches the first characteristic polarization. The subscriber terminals in the second beam may have a polarization that matches the second characteristic polarization.
The subscriber terminals in the overlap region of the adjacent beams may be optionally assigned to the first beam or to the second beam. This optional assignment is a degree of flexibility within the satellite system and may be altered through reassignment following the start of service for any subscriber terminals within the overlapping region. The ability to remotely change the polarization of a subscriber terminal in an overlapping region illuminated by adjacent spot beams is an important improvement in the operation and optimization of the use of the satellite resources for changing subscriber distributions and quantities. For example it may be an efficient use of satellite resources and improvement to the individual subscriber service to reassign a user or a group of users from a first beam to a second beam or from a second beam to a first beam. Satellite systems using polarization as a quantity to provide isolation between adjacent beams may thus be configured to change the polarization remotely by sending a signal containing a command to switch or change the polarization from a first polarization state to a second orthogonal polarization state. The intentional changing of the polarization may facilitate reassignment to an adjacent beam in a spot beam satellite system using polarization for increasing a beam isolation quantity.
The down link may comprise multiple “colors” based on combinations of selected frequency and/or polarizations. Although other frequencies and frequency ranges may be used, and other polarizations as well, an example is provided of one multicolor embodiment. For example, and with renewed reference to FIG. 28, in the downlink, colors U1, U3, and U5 are Left-Hand Circular Polarized (“LHCP”) and colors U2, U4, and U6 are Right-Hand Circular Polarized (“RHCP”). In the frequency domain, colors U3 and U4 are from 18.3-18.8 GHz; U5 and U6 are from 18.8-19.3 GHz; and U1 and U2 are from 19.7-20.2 GHz. It will be noted that in this exemplary embodiment, each color represents a 500 MHz frequency range. Other frequency ranges may be used in other exemplary embodiments. Thus, selecting one of LHCP or RHCP and designating a frequency band from among the options available will specify a color. Similarly, the uplink comprises frequency/polarization combinations that can be each designated as a color. Often, the LHCP and RHCP are reversed as illustrated, providing increased signal isolation, but this is not necessary. In the uplink, colors U1, U3, and U5 are RHCP and colors U2, U4, and U6 are LHCP. In the frequency domain, colors U3 and U4 are from 28.1-28.6 GHz; U5 and U6 are from 28.6-29.1 GHz; and U1 and U2 are from 29.5-30.0 GHz. It will be noted that in this exemplary embodiment, each color similarly represents a 500 MHz frequency range.
In an exemplary embodiment, the satellite may broadcast one or more RF signal beam (spot beam) associated with a spot and a color. This satellite is further configured to change the color of the spot from a first color to a second, different, color. Thus, with renewed reference to FIG. 29A, spot 1 is changed from “red” to “blue.”
When the color of one spot is changed, it may be desirable to change the colors of adjacent spots as well. Again with reference to FIG. 29A, the map shows a group of spot colors at a first point in time, where this group at this time is designated 9110, and a copy of the map shows a group of spot colors at a second point in time, designated 9120. Some or all of the colors may change between the first point in time and the second point in time. For example spot 1 changes from red to blue and spot 2 changes from blue to red. Spot 3, however, stays the same. In this manner, in an exemplary embodiment, adjacent spots are not identical colors.
Some of the spot beams are of one color and others are of a different color. For signal separation, the spot beams of similar color are typically not located adjacent to each other. In an exemplary embodiment, and with reference again to FIG. 28, the distribution pattern illustrated provides one exemplary layout pattern for four color spot beam frequency re-use. It should be recognized that with this pattern, color U1 will not be next to another color U1, etc. It should be noted, however, that typically the spot beams will over lap and that the spot beams may be better represented with circular areas of coverage. Furthermore, it should be appreciated that the strength of the signal may decrease with distance from the center of the circle, so that the circle is only an approximation of the coverage of the particular spot beam. The circular areas of coverage may be overlaid on a map to determine what spot beam(s) are available in a particular area.
In accordance with an exemplary embodiment, the satellite is configured to shift one or more spots from a first geographic location to a second geographic location. This may be described as shifting the center of the spot from a first location to a second location. This might also be described as changing the effective size (e.g., diameter) of the spot. In accordance with an exemplary embodiment, the satellite is configured to shift the center of the spot from a first location to a second location and/or change the effective size of one or more spots. In the prior art, it would be unthinkable to shift a spot because such an action would strand terrestrial transceivers. The terrestrial transceivers would be stranded because the shifting of one or more spots would leave some terrestrial terminals unable to communicate with a new spot of a different color.
However, in an exemplary embodiment, the transceivers are configured to easily switch colors. Thus, in an exemplary method, the geographic location of one or more spots is shifted and the color of the terrestrial transceivers may be adjusted as needed.
In an exemplary embodiment, the spots are shifted such that a high load geographic region is covered by two or more overlapping spots. For example, with reference to FIGS. 29B and 29C, a particular geographic area 9210 may have a very high load of data traffic. In this exemplary embodiment, area 9210 is only served by spot 1 at a first point in time illustrated by FIG. 29B. At a second point in time illustrated by FIG. 29C, the spots have been shifted such that area 9210 is now served or covered by spots 1, 2, and 3. In this embodiment, terrestrial transceivers in area 9210 may be adjusted such that some of the transceivers are served by spot 1, others by spot 2, and yet others by spot 3. In other words, transceivers in area 9210 may be selectively assigned one of three colors. In this manner, the load in this area can be shared or load-balanced.
In an exemplary embodiment, the switching of the satellites and/or terminals may occur with any regularity. For example, the polarization may be switched during the evening hours, and then switched back during business hours to reflect transmission load variations that occur over time. In an exemplary embodiment, the polarization may be switched thousands of times during the life of elements in the system.
In one exemplary embodiment, the color of the terminal is not determined or assigned until installation of the terrestrial transceiver. This is in contrast to units shipped from the factory set as one particular color. The ability to ship a terrestrial transceiver without concern for its “color” facilitates simpler inventory processes, as only one unit (as opposed to two or four or more) need be stored. In an exemplary embodiment, the terminal is installed, and then the color is set in an automated manner (i.e., the technician can't make a human error) either manually or electronically. In another exemplary embodiment, the color is set remotely such as being assigned by a remote central control center. In another exemplary embodiment, the unit itself determines the best color and operates at that color.
As can be noted, the determination of what color to use for a particular terminal may be based on any number of factors. The color may be based on what signal is strongest, based on relative bandwidth available between available colors, randomly assigned among available colors, based on geographic considerations, based on temporal considerations (such as weather, bandwidth usage, events, work patterns, days of the week, sporting events, and/or the like), and or the like. Previously, a terrestrial consumer broadband terminal was not capable of determining what color to use based on conditions at the moment of install or quickly, remotely varied during use.
In accordance with an exemplary embodiment, the system is configured to facilitate remote addressability of subscriber terminals. In one exemplary embodiment, the system is configured to remotely address a specific terminal. The system may be configured to address each subscriber terminal. In another exemplary embodiment, a group of subscriber terminals may be addressable. This may occur using any number of methods now known, or hereafter invented, to communicate instructions with a specific transceiver and/or group of subscriber terminals. Thus, a remote signal may command a terminal or group of terminals to switch from one color to another color. The terminals may be addressable in any suitable manner. In one exemplary embodiment, an internet protocol (IP) address is associated with each terminal. In an exemplary embodiment, the terminals may be addressable through the modems or set top boxes (e.g., via the internet). Thus, in accordance with an exemplary embodiment, the system is configured for remotely changing a characteristic polarization of a subscriber terminal by sending a command addressed to a particular terminal. This may facilitate load balancing and the like. The sub-group could be a geographic sub group within a larger geographic area, or any other group formed on any suitable basis.
In this manner, an individual unit may be controlled on a one to one basis. Similarly, all of the units in a sub-group may be commanded to change colors at the same time. In one embodiment, a group is broken into small sub-groups (e.g., 100 sub-groups each comprising 1% of the terminals in the larger grouping). Other sub-groups might comprise 5%, 10%, 20%, 35%, 50% of the terminals, and the like. The granularity of the subgroups may facilitate more fine tuning in the load balancing.
Thus, an individual with a four color switchable transceiver that is located at location A on the map (see FIG. 28, Practical Distribution Illustration), would have available to them colors U1, U2, and U3. The transceiver could be switched to operate on one of those three colors as best suits the needs at the time. Likewise, location B on the map would have colors U1 and U3 available. Lastly, location C on the map would have color U1 available. In many practical circumstances, a transceiver will have two or three color options available in a particular area.
It should be noted that colors U5 and U6 might also be used and further increase the options of colors to use in a spot beam pattern. This may also further increase the options available to a particular transceiver in a particular location. Although described as a four or six color embodiment, any suitable number of colors may be used for color switching as described herein. Also, although described herein as a satellite, it is intended that the description is valid for other similar remote communication systems that are configured to communicate with the transceiver.
The frequency range/polarization of the terminal may be selected at least one of remotely, locally, manually, or some combination thereof. In one exemplary embodiment, the terminal is configured to be remotely controlled to switch from one frequency range/polarization to another. For example, the terminal may receive a signal from a central system that controls switching the frequency range/polarization. The central system may determine that load changes have significantly slowed down the left hand polarized channel, but that the right hand polarized channel has available bandwidth. The central system could then remotely switch the polarization of a number of terminals. This would improve channel availability for switched and non-switched users alike. Moreover, the units to switch may be selected based on geography, weather, use characteristics, individual bandwidth requirements, and/or other considerations. Furthermore, the switching of frequency range/polarization could be in response to the customer calling the company about poor transmission quality.
It should be noted that although described herein in the context of switching both frequency range and polarization, benefits and advantages similar to those discussed herein may be realized when switching just one of frequency or polarization.
The frequency range switching described herein may be performed in any number of ways. In an exemplary embodiment, the frequency range switching is performed electronically. For example, the frequency range switching may be implemented by adjusting phase shifters in a phased array, switching between fixed frequency oscillators or converters, and/or using a tunable dual conversion transmitter comprising a tunable oscillator signal. Additional aspects of frequency switching for use with the present invention are disclosed in U.S. application Ser. No. 12/614,293 entitled “DUAL CONVERSION TRANSMITTER WITH SINGLE LOCAL OSCILLATOR” which was filed on Nov. 6, 2009; the contents of which are hereby incorporated by reference in their entirety.
In accordance with another exemplary embodiment, the polarization switching described herein may be performed in any number of ways. In an exemplary embodiment, the polarization switching is performed electronically by adjusting the relative phase of signals at orthogonal antenna ports. In another exemplary embodiment, the polarization switching is performed mechanically. For example, the polarization switching may be implemented by use of a trumpet switch. The trumpet switch may be actuated electronically. For example, the trumpet switch may be actuated by electronic magnet, servo, an inductor, a solenoid, a spring, a motor, an electro-mechanical device, or any combination thereof. Moreover, the switching mechanism can be any mechanism configured to move and maintain the position of trumpet switch. Furthermore, in an exemplary embodiment, trumpet switch is held in position by a latching mechanism. The latching mechanism, for example, may be fixed magnets. The latching mechanism keeps trumpet switch in place until the antenna is switched to another polarization.
As described herein, the terminal may be configured to receive a signal causing switching and the signal may be from a remote source. For example, the remote source may be a central office. In another example, an installer or customer can switch the polarization using a local computer connected to the terminal which sends commands to the switch. In another embodiment, an installer or customer can switch the polarization using the television set-top box which in turn sends signals to the switch. The polarization switching may occur during installation, as a means to increase performance, or as another option for troubleshooting poor performance.
In other exemplary embodiments, manual methods may be used to change a terminal from one polarization to another. This can be accomplished by physically moving a switch within the housing of the system or by extending the switch outside the housing to make it easier to manually switch the polarization. This could be done by either an installer or customer.
Some exemplary embodiments of the above mentioned multi-color embodiments may benefits over the prior art. For instance, in an exemplary embodiment, a low cost consumer broadband terrestrial terminal antenna system may include an antenna, a transceiver in signal communication with the antenna, and a polarity switch configured to cause the antenna system to switch between a first polarity and a second polarity. In this exemplary embodiment, the antenna system may be configured to operate at the first polarity and/or the second polarity.
In an exemplary embodiment, a method of system resource load balancing is disclosed. In this exemplary embodiment, the method may include the steps of: (1) determining that load on a first spotbeam is higher than a desired level and that load on a second spotbeam is low enough to accommodate additional load; (2) identifying, as available for switching, consumer broadband terrestrial terminals on the first spot beam that are in view of the second spotbeam; (3) sending a remote command to the available for switching terminals; and (4) switching color in said terminals from the first beam to the second beam based on the remote command. In this exemplary embodiment, the first and second spot beams are each a different color.
In an exemplary embodiment, a satellite communication system is disclosed. In this exemplary embodiment, the satellite communication system may include: a satellite configured to broadcast multiple spotbeams; a plurality of user terminal antenna systems in various geographic locations; and a remote system controller configured to command at least some of the subset of the plurality of user terminal antenna systems to switch at least one of a polarity and a frequency to switch from the first spot beam to the second spotbeam. In this exemplary embodiment, the multiple spot beams may include at least a first spotbeam of a first color and a second spotbeam of a second color. In this exemplary embodiment, at least a subset of the plurality of user terminal antenna systems may be located within view of both the first and second spotbeams.
The following applications are related to this subject matter: U.S. application Ser. No. 14/617,630, entitled MULTI-BEAM ACTIVE PHASED ARRAY ARCHITECTURE WITH INDEPENDENT POLARIZATION CONTROL,” filed on Feb. 9, 2015; U.S. application Ser. No. 14/216,760, entitled MULTI-BEAM ACTIVE PHASED ARRAY ARCHITECTURE WITH INDEPENDENT POLARIZATION CONTROL,” filed on Mar. 17, 2014; U.S. application Ser. No. 12/759,123, entitled “ACTIVE BUTLER AND BLASS MATRICES,” filed on Apr. 13, 2010; U.S. application Ser. No. 12/759,043, entitled “ACTIVE HYBRIDS FOR ANTENNA SYSTEMS,” filed on Apr. 13, 2010; U.S. application Ser. No. 12/759,064, entitled “ACTIVE FEED FORWARD AMPLIFIER,” filed on Apr. 13, 2010; U.S. application Ser. No. 12/759,130, entitled “ACTIVE PHASED ARRAY ARCHITECTURE,” filed on Apr. 13, 2010; U.S. application Ser. No. 12/758,996, entitled “PRESELECTOR AMPLIFIER,” filed on Apr. 13, 2010; U.S. application Ser. No. 12/759,148, entitled “ACTIVE POWER SPLITTER,” filed on Apr. 13, 2010; U.S. application Ser. No. 12/759,112, entitled “HALF-DUPLEX PHASED ARRAY ANTENNA SYSTEM,” filed on Apr. 13, 2010; U.S. application Ser. No. 12/759,113, entitled “DIGITAL AMPLITUDE CONTROL OF ACTIVE VECTOR GENERATOR,” filed on Apr. 13, 2010; the contents of which are hereby incorporated by reference for any purpose in their entirety.
Benefits, other advantages, and solutions to problems have been described above with regard to specific embodiments. However, the benefits, advantages, solutions to problems, and any element(s) that may cause any benefit, advantage, or solution to occur or become more pronounced are not to be construed as critical, required, or essential features or elements of any or all the claims. As used herein, the terms “includes,” “including,” “comprises,” “comprising,” or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Further, no element described herein is required for the practice of the invention unless expressly described as “essential” or “critical.”

## Claims

1. A method of satellite communication, the method comprising:
providing a plurality of user terminal antenna systems within an overlapping region of a first spot beam and a second spot beam of a satellite, wherein at least one of a polarization and a frequency range of the first spot beam is different from a polarization and a frequency range of the second spot beam;
providing first commands to a first group of user terminal antenna systems of the plurality of user terminal antenna systems to communicate with the satellite via the first spot beam, wherein the first commands are to electronically configure transceivers of the first group of user terminal antenna systems to match the polarization and frequency range of the first spot beam;
providing second commands to a second group of user terminal antenna systems of the plurality of user terminal antenna systems to communicate with the satellite via the second spot beam, wherein the second commands are to electronically configure transceivers of the second group of user terminal antenna systems to electronically configure transceivers of the second group of user terminal antenna systems to match the polarization and frequency range of the second spot beam;
obtaining an indication that load on the first spot beam is higher than a desired level and that load on the second spot beam is low enough to accommodate additional load; and
in response to obtaining the indication, providing third commands to a sub-group of user terminal antenna systems of the first group of user terminal antenna systems to switch communication with the satellite to the second spot beam, wherein the third commands are to electronically reconfigure transceivers of the sub-group of user terminal antenna systems to match the polarization and frequency range of the second spot beam.

2. The method of claim 1, wherein:
the frequency range of the first spot beam is different than the frequency range of the second spot beam; and
the third commands are to change an operating frequency of the transceivers of the sub-group of user terminal antenna systems from the frequency range of the first spot beam to the frequency range of the second spot beam.

3. The method of claim 2, wherein the operating frequency of each transceiver of the sub-group of user terminal antenna systems is changed by adjusting phase shifters in a phased array, switching between fixed frequency oscillators, switching between fixed frequency converters, using a tunable dual conversion transmitter comprising a tunable oscillator signal, and combinations thereof.

4. The method of claim 1, wherein:
the polarization of the first spot beam is different than the polarization of the second spot beam; and
the third commands are to change an operating polarization of the transceivers of the sub-group of user terminal antenna systems from the polarization of the first spot beam to the polarization of the second spot beam.

5. The method of claim 4, wherein the operating polarization of each transceiver of the sub-group of user terminal antenna systems is changed by adjusting a relative phase of signals at orthogonal antenna ports.

6. The method of claim 4, wherein:
the transceivers of the plurality of user terminal antenna systems comprise active antenna polarizers; and
the operating polarization of the transceivers of the sub-group of user terminal antenna systems are changed by the active antenna polarizers in response to the third commands.

7. The method of claim 6, wherein the active antenna polarizers comprise vector generators to adjust at least one of phase and amplitude of a radio frequency signal communicated with the satellite.

8. The method of claim 1, further comprising periodically providing fourth commands to at least some of the plurality of user terminal antenna systems to switch between the polarization and the frequency range of the first spot beam and the polarization and the frequency range of the second spot beam in response to further changes in load on the first spot beam and the second spot beam.

9. The method of claim 1, further comprising shifting of at least one of the first and second spot beams of the satellite to change the overlapping region from a first region to a second region.

10. The method of claim 9, wherein the shifting of at least one of the first and second spot beams of the satellite is based on higher data traffic load within the second region than that within the first region.

11. The method of claim 1, wherein the load on the first spot beam is higher than the desired level is due to one or more of seasonal load variations, a higher than average population density within a particular region, a higher than average number of user terminal antenna systems within the particular region, and a higher than average usage of data transmissions.

12. The method of claim 1, wherein the sub-group of user terminal antenna systems are a particular terminal type.

13. The method of claim 1, wherein the polarization of the first spot beam comprises an uplink polarization and a downlink polarization, and the frequency range of the first spot beam comprises an uplink frequency range and a downlink frequency range.

14. The method of claim 1, further comprising a third spot beam of the satellite illuminating the overlapping region, and at least one of a polarization and a frequency range of the third spot beam is different from the polarization and the frequency range of the first spot beam and from the polarization and the frequency range of the second spot beam.

15. The method of claim 14, further comprising, in response to obtaining the indication, providing fourth commands to a second sub-group of user terminal antenna systems of the first group of user terminal antenna systems to switch communication with the satellite to the third spot beam, wherein the fourth commands are to electronically reconfigure transceivers of the second sub-group of user terminal antenna systems to match the polarization and frequency range of the third spot beam.

16. The method of claim 1, wherein each of the plurality of user terminal antenna systems are individually addressable.

17. The method of claim 1, wherein the sub-group of user terminal antenna systems is at least 5% of the first group of user terminal antenna systems.

18. The method of claim 17, wherein at least one user terminal antenna system of the sub-group of user terminal antenna systems is attached to a mobile platform.

19. The method of claim 18, wherein the mobile platform is an airplane, a train or an automobile.

20. A satellite communication system comprising:
a satellite communicating using a first spot beam and a second spot beam, wherein the first spot beam and the second spot beam each illuminate an overlapping region within a geographic area, and wherein at least one of a polarization and a frequency range of the first spot beam is different from a polarization and a frequency range of the second spot beam; and
a system controller to assign each of a plurality of user terminal antenna systems within the overlapping region to the first spot beam or the second spot beam, the system controller to:
provide first commands to a first group of user terminal antenna systems of the plurality of user terminal antenna systems to communicate with the satellite via the first spot beam, wherein the first commands are to electronically configure transceivers of the first group of user terminal antenna systems to match the polarization and frequency range of the first spot beam;
provide second commands to a second group of user terminal antenna systems of the plurality of user terminal antenna systems to communicate with the satellite via the second spot beam, wherein the second commands are to electronically configure transceivers of the second group of user terminal antenna systems to match the polarization and frequency range of the second spot beam;
obtain an indication that load on the first spot beam is higher than a desired level and that load on the second spot beam is low enough to accommodate additional load; and
in response to obtaining the indication, providing third commands to a sub-group of user terminal antenna systems of the first group of user terminal antenna systems to switch communication with the satellite to the second spot beam, wherein the third commands are to electronically reconfigure transceivers of the sub-group of user terminal antenna systems to match the polarization and frequency range of the second spot beam.

21. The satellite communication system of claim 20, wherein:
the frequency range of the first spot beam is different than the frequency range of the second spot beam; and
the third commands are to change an operating frequency of the transceivers of the sub-group of user terminal antenna systems from the frequency range of the first spot beam to the frequency range of the second spot beam.

22. The satellite communication system of claim 21, wherein the operating frequency of each transceiver of the sub-group of user terminal antenna systems is changed by adjusting phase shifters in a phased array, switching between fixed frequency oscillators, switching between fixed frequency converters, using a tunable dual conversion transmitter comprising a tunable oscillator signal, and combinations thereof.

23. The satellite communication system of claim 20, wherein:
the polarization of the first spot beam is different than the polarization of the second spot beam; and
the third commands are to change an operating polarization of the transceivers of the sub-group of user terminal antenna systems from the polarization of the first spot beam to the polarization of the second spot beam.

24. The satellite communication system of claim 23, wherein the operating polarization of each transceiver of the sub-group of user terminal antenna systems is changed by adjusting a relative phase of signals at orthogonal antenna ports.

25. The satellite communication system of claim 23, wherein:
the transceivers of the plurality of user terminal antenna systems comprise active antenna polarizers; and
the operating polarization of the transceivers of the sub-group of user terminal antenna systems are changed by the active antenna polarizers in response to the third commands.

26. The satellite communication system of claim 25, wherein the active antenna polarizers comprise vector generators to adjust at least one of phase and amplitude of a radio frequency signal communicated with the satellite.

27. The satellite communication system of claim 20, where the system controller is further to periodically provide fourth commands to at least some of the plurality of user terminal antenna systems to switch between the polarization and the frequency range of the first spot beam and the polarization and the frequency range of the second spot beam in response to further changes in load on the first spot beam and the second spot beam.

28. The satellite communication system of claim 20, wherein the system controller is further to provide commands to the satellite to shift at least one of the first and second spot beams of the satellite to change the overlapping region from a first region to a second region.

29. The satellite communication system of claim 28, wherein the commands to shift at least one of the first and second spot beams of the satellite is based on higher data traffic load within the second region than that within the first region.

30. The satellite communication system of claim 20, wherein the load on the first spot beam is higher than the desired level is due to one or more of seasonal load variations, a higher than average population density within a particular region, a higher than average number of user terminal antenna systems within the particular region, and a higher than average usage of data transmissions.

31. The satellite communication system of claim 20, wherein the sub-group of user terminal antenna systems are a particular terminal type.

32. The satellite communication system of claim 20, wherein the polarization of the first spot beam comprises an uplink polarization and a downlink polarization, and the frequency range of the first spot beam comprises an uplink frequency range and a downlink frequency range.

33. The satellite communication system of claim 20, wherein the satellite further communicates using a third spot beam of the satellite illuminating the overlapping region, and at least one of a polarization and a frequency range of the third spot beam is different from the polarization and the frequency range of the first spot beam and from the polarization and the frequency range of the second spot beam.

34. The satellite communication system of claim 33, wherein the system controller is further to, in response to obtaining the indication, provide fourth commands to a second sub-group of user terminal antenna systems of the first group of user terminal antenna systems to switch communication with the satellite to the third spot beam, wherein the fourth commands are to electronically reconfigure transceivers of the second sub-group of user terminal antenna systems to match the polarization and frequency range of the third spot beam.

35. The satellite communication system of claim 20, wherein each of the plurality of user terminal antenna systems are individually addressable.

36. The satellite communication system of claim 20, wherein the sub-group of user terminal antenna systems is at least 5% of the first group of user terminal antenna systems.

37. The satellite communication system of claim 36, wherein at least one user terminal antenna system of the sub-group of user terminal antenna systems is attached to a mobile platform.

38. The satellite communication system of claim 37, wherein the mobile platform is an airplane, a train or an automobile.