Patent Description:
For phased antenna arrays, performance parameters are typically measured over the operational bandwidth and temperature. Measuring the performance parameters involves over-the-air testing, typically done in the far field. Traditional antenna metrology requires expensive, large test stations - for example far-field anechoic chambers or compact range. The traditional approaches for performing factory acceptance testing are adequate in low-volume markets (e.g. fire-control fighter jet radar phased arrays) but are completely inadequate in high-volume markets (e.g. <NUM> base station phased arrays) or moderate-volume markets (e.g. airborne satcom phased arrays). In particular, most traditional testing techniques are expensive, require relatively large testing space, and may not be adequate to perform some performance measurements.

Anechoic chambers, which are commonly used in testing phased antenna arrays and other antennas can be costly. The cost usually increases with size of the chamber. Also, most testing equipment can be costly and difficult to control or monitor. Such difficulty can make the testing process slow, therefore, adding more to the total cost.

<CIT> discloses an antenna array system and a method for calibrating an antenna array system. <CIT> discloses an arrangement for testing the performance of an electronic system employing a phased array antenna for electromagnetic radiation scanning of a sector in space.

In one aspect, embodiments of the inventive concepts disclosed herein are directed to a method of testing phased antenna arrays. The method can include positioning a phased antenna array and a probe antenna at relative positions with respect to each other. The phased antenna array can include a plurality of antenna elements. Either the phased antenna array can act as a transmitting antenna and the probe antenna can act as a receiving antenna, or the probe antenna can act as the transmitting antenna and the phased antenna array can act as the receiving antenna. The method can include causing the transmitting antenna to radiate a plurality of electromagnetic waves sequentially. The method can include causing the phased antenna array to operate, during transmission of each electromagnetic wave of the plurality of electromagnetic waves, according to a corresponding configuration scheme. The corresponding configuration scheme can define a respective set of antenna elements that are active during the transmission of the electromagnetic wave or a respective phase coding scheme applied to the plurality of antenna elements during the transmission of the electromagnetic wave. The method can include receiving, by the receiving antenna, responsive to each radiated electromagnetic wave, a corresponding receive radio frequency (RF) signal. The method can include determining, for each antenna element of the plurality of antenna elements, corresponding amplitude and phase parameters using the receive RF signals. The method can include determining one or more performance parameters of the phased antenna array using the determined amplitude and phase parameters for the plurality of antenna elements.

In a further aspect, the antenna subarrays can include a group of antenna subarrays with corresponding antenna elements having a respective size and supporting a respective frequency subband. The antenna subarrays can include another group of antenna subarrays with corresponding antenna elements having a different size and supporting a different frequency subband.

In a further aspect, the method can include positioning the probe antenna at a near field location relative to the phased antenna array. The one or more performance parameters can include co-polarized antenna gain, cross-polarized antenna gain, co-polarized antenna directivity, cross-polarized antenna directivity, antenna beam width, radiated power, cross-polarization discrimination, antenna gain-to-noise-temperature, error vector magnitude, adjacent channel power ratio, pulse quality, one or more side lobe levels, signal-to-noise ratio (SNR), or a combination thereof.

In a further aspect, the method can include determining a far field response of the phased antenna array using the determined amplitude and phase parameters for each of the plurality of antenna elements. In a further aspect, causing the phased antenna array to operate according to a corresponding configuration scheme can include activating the plurality of antenna elements one at a time. Each antenna element can be activated to transmit an electromagnetic wave of the plurality of electromagnetic waves and the probe antenna can receive, responsive to transmission of the electromagnetic wave by the antenna element, the corresponding receive RF signal. Each antenna element can be activated to receive, responsive to transmission of an electromagnetic wave of the plurality of electromagnetic waves by the probe antenna, the corresponding receive RF signal. The method can further comprise determining, for each antenna element of the plurality of antenna elements, the corresponding amplitude and phase parameters using the corresponding receive RF signal received during activation of the antenna element.

In a further aspect, causing the phased antenna array to operate according to a corresponding configuration scheme can include phase steering the plurality of antenna elements, during transmission of each electromagnetic wave of the plurality of electromagnetic waves, according to a respective phase coding scheme. Each phase coding scheme can define a corresponding set of phase shifts or a corresponding set of time delays applied to the plurality of antenna elements during transmission of a corresponding electromagnetic wave of the plurality of electromagnetic waves. The method can further comprise transmitting each electromagnetic wave of the plurality of electromagnetic waves by the plurality of antenna elements phase steered according to the corresponding set of phase shifts or the corresponding set of time delays. The antenna probe can receive, responsive to transmission of the electromagnetic wave by the plurality of antenna elements, the corresponding receive RF signal. The method may comprise transmitting each electromagnetic wave of the plurality of electromagnetic waves by the probe antenna and the phased antenna array can receive, responsive to transmission of the electromagnetic wave by the antenna probe, the corresponding receive RF signal.

In a further aspect, causing the phased antenna array to operate according to a corresponding configuration scheme can include phase steering a group of active antenna elements of the plurality of antenna elements, during transmission of each electromagnetic wave of the plurality of electromagnetic waves, according to a respective phase coding scheme.

In a further aspect, the method can further include modifying the relative positions by causing the antenna probe or the phased antenna array to move along a predefined path during transmission of the plurality of electromagnetic waves.

In a further aspect, the method can include positioning at least two antenna probes with distinct polarizations, or positioning a single dual polarized antenna probe. In a further aspect, the method can include positioning a plurality of probe antennas operating at different center frequencies at various positions relative to the phased antenna array.

In a further aspect, the method can include applying a predefined phase offset to the plurality of antenna elements, and receiving one or more additional receive signals at an angle offset with respect to a main lobe of the receiving antenna.

In one aspect, embodiments of the inventive concepts disclosed herein are directed to a method of testing phased antenna arrays. The method can include positioning a phased antenna array including a plurality of antenna elements and a probe antenna at relative positions with respect to each other. Either the phased antenna array can act as a transmitting antenna and the probe antenna can act as a receiving antenna, or the probe antenna can act as the transmitting antenna and the phased antenna array can act as the receiving antenna. The method can include applying, to each antenna element of the plurality of antenna elements, a corresponding phase shift or a corresponding time delay to compensate for differences in signal propagation times between the probe antenna and each of the plurality of antenna elements. The method can include causing the transmitting antenna to radiate an electromagnetic wave. The method can include receiving, by the receiving antenna, a receive radio frequency (RF) signal responsive to radiating the electromagnetic wave. The method can include determining one or more performance parameters of the phased antenna array using the receive RF signal.

In a further aspect, the method can include positioning the probe antenna at a near field location relative to the phased antenna array. In a further aspect, the one or more performance parameters can include co-polarized antenna gain, cross-polarized antenna gain, co-polarized antenna directivity, cross-polarized antenna directivity, antenna beamwidth, radiated power, cross-polarization discrimination, antenna gain-to-noise-temperature, error vector magnitude, adjacent channel power ratio, pulse quality, one or more side lobe levels, and signal-to-noise ratio (SNR).

In a further aspect, the method can include positioning at least two antenna probes with distinct polarizations, or positioning a single dual polarized antenna probe. In a further aspect, the method can include positioning a plurality of probe antennas operating at different center frequencies at one or more positions relative to the phased antenna array.

In one aspect, embodiments of the inventive concepts disclosed herein are directed to a system for testing phased antenna arrays. The system can include a signal generator circuit communicatively coupled to a phased antenna array including a plurality of antenna elements or a probe antenna positioned at a relative position with respect to the phased antenna array. The signal generator circuit can generate one or more transmit radio frequency (RF) signals for transmission by the phased antenna array or the probe antenna. Either the phased antenna array can act as a transmitting antenna and the antenna probe can act as a receiving antenna, or the antenna probe can act as the transmitting antenna and the phased antenna array can act as the receiving antenna. The system can include a processor communicatively coupled to the signal generator circuit, the phased antenna array, and the probe antenna. The processor can cause the transmitting antenna to sequentially radiate a plurality of electromagnetic waves associated with the one or more transmit RF signals. The processor can cause the phased antenna array to operate, during transmission of each electromagnetic wave of the plurality of electromagnetic waves, according to a corresponding configuration scheme. The corresponding configuration scheme can define a respective set of antenna elements that are active during the transmission of the electromagnetic wave or a respective phase coding scheme applied to the plurality of antenna elements during the transmission of the electromagnetic wave. The processor can obtain, from the receiving antenna, responsive to each radiated electromagnetic wave, a corresponding receive RF signal, the receive RF signal received by the receiving antenna responsive to the radiated electromagnetic wave. The processor can determine, for each antenna element of the plurality of antenna elements, corresponding amplitude and phase parameters using the receive RF signals. The processor can determine one or more performance parameters of the phased antenna array using the determined amplitude and phase parameters for the plurality of antenna elements.

In a further aspect, the processor can be embedded within the phased antenna array.

The details of various embodiments of the methods and systems are set forth in the accompanying drawings and the description below.

Before describing in detail embodiments of the inventive concepts disclosed herein, it should be observed that the inventive concepts disclosed herein include, but are not limited to a novel structural combination of components and circuits, and not to the particular detailed configurations thereof. Accordingly, the structure, methods, functions, control and arrangement of components and circuits have, for the most part, been illustrated in the drawings by readily understandable block representations and schematic diagrams, in order not to obscure the disclosure with structural details which will be readily apparent to those skilled in the art, having the benefit of the description herein. Further, the inventive concepts disclosed herein are not limited to the particular embodiments depicted in the diagrams provided in this disclosure, but should be construed in accordance with the language in the claims.

Methods and systems described herein allow phased antenna array testing methods that are accurate, relatively fast (e.g., compared to conventional testing techniques), efficient. While conventional antenna testing methods may allow for testing one or very few phased antenna arrays per day, the methods and systems described herein allow for testing many phased antenna arrays per day. For instance, the methods described below with regard to <FIG> and <FIG> can allow for determining the radiation pattern of a phased antenna array in about seven seconds instead of hours. The increased testing speed allows for using a relatively smaller number of testing systems (or testing equipment) to test a given number (e.g., thousands) of phased antenna arrays, and therefore, reduces the testing space used. The reduction in testing equipment used reduces the testing cost and so does the reduction of testing space since anechoic chambers are very costly and their cost increases with their size.

Also, conventional antenna testing methods and systems usually employ moving mechanical parts (e.g., motors) that need to be maintained. These moving mechanical parts can add to the complexity of the testing methods and slow the testing process. Specifically, using a motor to rotate or move a robe antenna or a phased antenna array can be much slower and less accurate than steering antenna elements of the phased antenna array by applying a set of time delays or phase shifts.

Referring now to the drawings, <FIG> shows a diagram illustrating an example embodiment of a phased antenna array testing environment <NUM>, according to inventive concepts of this disclosure. In brief overview, the phased antenna array testing environment <NUM> can include an antenna testing chamber <NUM>, an antenna testing control system <NUM>, a phased antenna array <NUM>, and one or more probe antennas, such as probe antennas 108a-108c which are referred to hereinafter either individually or in combination as probe antenna(s) <NUM>. The antenna testing control system <NUM>, the phased antenna array <NUM>, and the one or more probe antennas <NUM> can be arranged within the antenna testing chamber <NUM>. The antenna testing control system <NUM> and the one or more probe antennas <NUM> can be viewed as forming a phased antenna array testing system <NUM> for testing the phased antenna array <NUM>. While <FIG> shows a single phased antenna array <NUM> being tested, the phased antenna array testing system <NUM> can be used to test a plurality of phased antenna arrays <NUM> as discussed in further detail below.

The antenna testing chamber <NUM> can include a radio frequency (RF) anechoic chamber. A RF anechoic chamber can be a room designed to completely, or substantially, absorb reflections of electromagnetic waves radiated by the phased antenna array <NUM> or the one or more probe antennas <NUM>. For instance, the walls, ceiling and floor of the RF anechoic chamber can be made of or lined with electromagnetic wave absorbing material. The walls and ceiling of the RF anechoic chamber can also be designed to block electromagnetic waves in the surrounding environment from penetrating into anechoic chamber. The testing chamber <NUM> can be sized to host the phased antenna array testing system <NUM> and the phased antenna array(s) <NUM> to be tested. For instance, the size of the testing chamber <NUM> can be defined based on the sizes of components of the phased antenna array testing system <NUM>, the size of the phased antenna array(s) <NUM> to be tested, the number of phased antenna array(s) to be tested (e.g., per a given time duration), the distance(s) between the phased antenna array(s) <NUM> and the probe antenna(s) <NUM>, or a combination thereof.

In some implementations, the phased antenna array testing system <NUM> and the phased antenna array(s) <NUM> to be tested can be arranged in open space (or outdoor). Specifically, embodiments for testing phased antenna arrays described in this disclosure can be performed in an open space environment (not within a testing chamber <NUM>). For instance, an electromagnetic wave absorbing material can be laid on a portion of the ground between the phased antenna array(s) <NUM> and the probe antenna(s) <NUM> to prevent or mitigate reflections of the ground. Other techniques may be employed to eliminate or mitigate background noise within the open space testing environment.

An operator can use the phased antenna array testing system <NUM> to test the phased antenna array <NUM> by measuring one or more performance parameters of the phased antenna array <NUM>. The phased antenna array <NUM> can be an electronically scanned array (ESA) antenna or an active ESA (AESA) antenna. The phased antenna array <NUM> can include a plurality of antenna elements (also referred to as radiating elements) <NUM> that form an array. The array of antenna elements <NUM> can be a one-dimensional (<NUM>-D) array, a two-dimensional (<NUM>-D) array, or a three-dimensional (<NUM>-D) array. Each of the antenna elements <NUM> can act as a separate antenna configured to receive, transmit, or alternate between transmitting and receiving radio frequency (RF) signals. The phased antenna array <NUM> can include a network of RF amplifiers and phase shifters (or time delay elements) communicatively coupled to the plurality of antenna elements <NUM>. The network of RF amplifiers and phase shifters (or time delay elements) can allow for steering of beams received or transmitted by the phased antenna array <NUM>.

When manufactured, the phased antenna array <NUM> can be designed to have specific performance parameters (or radio characteristics) such as gain (G), directivity, radiation pattern, beam width, radiated power (or effective isotropic radiated power (EIRP)), cross correlation discrimination, gain-to-noise-temperature (G/T), error vector magnitude (EVM), adjacent channel power ratio (ACPR), pulse quality, side lobe levels, signal-to-noise ratio (SNR), or a combination thereof. However, due to manufacturing and/or design errors, the phased antenna array <NUM> may perform as desired and the actual performance parameters of the phased antenna array <NUM> may be different from the corresponding theoretical performance parameters defined, for example, during the design process of the phased antenna array <NUM>. The phased antenna array testing processes described herein allow for measuring the actual performance parameters (or radio characteristics) of the phased antenna array <NUM>.

During the testing processes described herein, the phased antenna array <NUM> can operate (or act) as transmitting antenna while the probe antenna(s) <NUM> can operate as receiving antenna(s), or the probe antenna(s) <NUM> can operate as transmitting antenna(s) while the phased antenna array <NUM> can operate (or act) as receiving antenna. For instance, the antenna testing control system <NUM> can cause a probe antenna <NUM> to radiate electromagnetic waves, and the phased antenna array <NUM> can receive, responsive to the transmission of the electromagnetic waves, corresponding RF signals. The antenna testing control system <NUM> may cause the phased antenna array <NUM> to radiate specific electromagnetic waves, and the probe antenna(s) <NUM> can receive, responsive to the transmission of the electromagnetic waves, corresponding receive RF signals. The antenna testing control system <NUM> can determine (or compute) one or more actual performance parameters of the phased antenna array <NUM> based on the received RF signals.

The probe antenna(s) <NUM> can include a horn antenna, a loop probe antenna, a rectangular antenna, a dipole antenna probe, or other type of antenna known to a person skilled in the art. The probe antenna(s) <NUM> can be single polarized or dual polarized. The one or more probe antenna(s) <NUM> may be arranged at fixed position(s) relative to the phased antenna array <NUM>. The one or more probe antenna(s) <NUM> may be arranged or positioned at different angles with respect to an axis <NUM> that is orthogonal to a front surface (planar or curved) of the phased antenna array <NUM> along which the antenna elements <NUM> are arranged. For instance, probe antenna 108a can be arranged at angle θ<NUM> = <NUM>°, the probe antenna 108b can be arranged at angle θ<NUM> = <NUM>°, and the probe antenna 108b can be arranged at angle θ<NUM> = <NUM>°. The points <NUM> indicate can be indicative of various angles or positions along which the one or more probe antennas <NUM> may be arranged. The axis <NUM> may be pointing to (or passing through) a center point of the phased antenna array <NUM>. The angles with respect to the axis <NUM> (or the points <NUM>) at which the probe antennas <NUM> may be positioned can be defined in a three-dimensional (3D) space. The points <NUM> defining potential angles, relative to the axis <NUM>, at which (or along which) the probe antennas <NUM> can be positioned or arranged can form a half sphere or a two-dimensional (2D) plane.

Referring to <FIG>, various arrangements of probe antennas <NUM> are illustrated, according to inventive concepts of this disclosure. As illustrated in <FIG>, the phased antenna array testing system <NUM> can include a horizontally polarized probe antenna <NUM>-<NUM> and a vertically polarized probe antenna <NUM>-<NUM>, or more generally at least two differently polarized probe antennas. The probe antennas <NUM>-<NUM> and <NUM>-<NUM> are also referred to hereinafter individually or collectively as probe antenna(s) <NUM>. The differently polarized probe antennas <NUM>-<NUM> and <NUM>-<NUM> may be arranged or positioned relatively close to each other (e.g., with corresponding angles relative to the axis <NUM> that are different by <NUM>° to <NUM>° or <NUM>° to <NUM>°) or substantially apart from each other (e.g., with corresponding angles relative to the axis <NUM> that are different by <NUM>° or more). The differently polarized probe antennas <NUM>-<NUM> and <NUM>-<NUM> may be positioned at different altitudes (e.g., relative to the ground or the floor of the antenna testing chamber <NUM>) or along the same altitude. The differently polarized probe antennas <NUM>-<NUM> and <NUM>-<NUM> allow for radiating or receiving dual polarized electromagnetic waves and, therefore, measuring performance parameters that are associated with distinct polarization components of the phased antenna array <NUM>. The phased antenna array testing system <NUM> may include multiple pairs of differently polarized probe antennas.

Referring to <FIG>, the phased antenna array testing system <NUM> can include a plurality of probe antennas <NUM>-<NUM> through <NUM>-n (referred to herein individually or in combination as probe antenna(s) <NUM>) operating at different frequency bands associated with different center frequencies f<NUM>,f<NUM>,. ,fn, where n is an integer greater than <NUM>. Each probe antenna <NUM>-i, where i = <NUM>, <NUM>,. , n, can be configured to operate at a corresponding center frequency fi of the frequencies f<NUM>, f<NUM>,. The probe antennas <NUM>-<NUM> through <NUM>-n can be arranged or positioned relatively close to each other (e.g., with corresponding angles relative to the axis <NUM> that are different by <NUM>° to <NUM>° or <NUM>° to <NUM>°) or substantially apart from each other (e.g., with corresponding angles relative to the axis <NUM> that are different by <NUM>° or more). The probe antennas <NUM>-<NUM> through <NUM>-n may be positioned at different altitudes (e.g., relative to the ground or the floor of the antenna testing chamber <NUM>) or along the same altitude. The phased antenna array testing system <NUM> may include a plurality of n-tuples of probe antennas (such as the n-tuple <NUM>-<NUM> through <NUM>-n). For instance, at least two of the n-tuples of probe antennas can be polarized differently (e.g., one n-tuple can be horizontally polarized and another can be vertically polarized). Probe antennas <NUM>-i operating at a given center frequency fi can be positioned at different locations (e.g., at different angles with respect to axis <NUM>). The use of probe antennas <NUM>-<NUM> through <NUM>-n operating at distinct frequency bands allows for radiating or receiving electromagnetic waves at different frequencies and assessing the performance parameters of the phased antenna array <NUM> over a wide frequency band (e.g., the combination of the frequency bands at which the probe antennas <NUM>-<NUM> through <NUM>-n operate). The use of probe antennas <NUM>-<NUM> through <NUM>-n operating at distinct frequency bands can allow determining the operating frequency band of the phased antenna array <NUM>.

Referring to <FIG>, the phased antenna array testing system <NUM> can include a probe antenna <NUM> configured to move relative to the phased antenna array <NUM>. A positioning system (not shown in <FIG> and <FIG>) can cause the probe antenna <NUM> to move, for example, along a predefined path (e.g., one or more straight lines or curves) or between predefined positions (e.g., positions indicated by points <NUM> in <FIG>). The positioning system may cause the phased antenna array <NUM>, or both probe antenna <NUM> and the phased antenna array <NUM>, to move according to corresponding predefined path(s) or between corresponding predefined positions. Using a moving probe antenna <NUM> and/or a moving phased antenna array <NUM> can facilitate measuring performance parameters for a plurality of phased antenna arrays <NUM> or measuring additional performance parameters (e.g., radiation pattern or one or more side lobe levels) of a phased antenna array <NUM>. For instance, when testing a plurality of phased antenna arrays <NUM>, the antenna testing control system <NUM> may cause the phased antenna arrays <NUM> to be activated one at a time and cause the probe antenna <NUM>, or the plurality of phased antenna arrays <NUM>, to move according to a predefined motion pattern, for example, such that the active phased antenna array <NUM> is positioned at a predefined location relative to the probe antenna(s) <NUM>. For example, the antenna testing control system <NUM> may (<NUM>) cause the phased antenna arrays <NUM> to be displaced, along a predefined path, by a specific distance, (<NUM>) activate the phased antenna array <NUM> located at a specific position, (<NUM>) cause radiation of electromagnetic waves between the active phased antenna array and the probe antenna(s) <NUM>, and (<NUM>) repeat the steps (<NUM>) through (<NUM>) until all phased antenna arrays <NUM> are activated for testing. In another example, the antenna testing control system <NUM> may cause the probe antenna <NUM> to move according to a plurality of predefined displacement and activate a distinct phased antenna array <NUM> after each displacement until all phased antenna arrays <NUM> are tested.

Other arrangements of probe antennas <NUM> are also contemplated by the current disclosure. For example, the phased antenna array testing system <NUM> can include one or more probe antennas <NUM> according to a combination of the arrangement discussed above with regard to <FIG>. For instance, the phased antenna array testing system <NUM> can include at least a pair of differently polarized probe antennas <NUM> that are configured to move relative to the phased antenna array <NUM>. The phased antenna array testing system <NUM> can include an n-tuple of probe antennas <NUM> that are configured to operate at different frequency bands and move relative to the phased antenna array <NUM>. The phased antenna array testing system <NUM> can include at least two n-tuples of probe antennas (with probe antennas <NUM> in each n-tuple operating at different frequency bands) that are polarized differently (e.g., one n-tuple can have horizontal polarization and another can have a vertical polarization). The at least two n-tuples of probe antennas may be configured to move relative to the phased antenna array <NUM>.

Referring back to <FIG>, the antenna testing control system <NUM> can be communicatively coupled to the phased antenna array(s) <NUM> and the probe antenna(s) <NUM>. The antenna testing control system <NUM> can include a combination of one or more electronic devices and one or more electric/electronic circuits. For instance, the antenna testing control system <NUM> can include a signal generator circuit, a network analyzer, a signal analyzer, a controller, a processor, a memory, a computing device, or a combination thereof. The antenna testing control system <NUM> can control electromagnetic wave radiation by the phased antenna array(s) <NUM> or the probe antenna(s) <NUM>. For example, the antenna testing control system <NUM> can generate and provide RF signals to be transmitted as electromagnetic waves by the phased antenna array(s) <NUM> or the probe antenna(s) <NUM>. The antenna testing control system <NUM> can control configuration schemes (or beam steering) of the phased antenna array(s) <NUM>. The antenna testing control system <NUM> can send instructions to the phased antenna array <NUM> indicative of a configuration scheme (or phase configuration scheme). A configuration scheme (or a phase configuration scheme) can be indicative of (or can define) a group of antenna elements <NUM> of the phased antenna array <NUM> to be activated, phase shifts (or time delays) for various antenna elements <NUM> (e.g., all the antenna elements <NUM> or a group of antenna elements to be activated), attenuations or power amplifications values for various antenna elements <NUM>, or a combination thereof. The antenna testing control system <NUM> can control the order and timing according to which the phase configuration schemes are implemented by the phased antenna array <NUM>.

The antenna testing control system <NUM> can obtain RF signals received by the receiving antenna(s) (the probe antenna(s) <NUM> or the phased antenna array <NUM>) and process the received RF signals received to determine or compute performance parameters of the phased antenna array <NUM>. The antenna testing control system <NUM> can calculate the performance parameters of the phased antenna array <NUM> and provide the calculated performance parameters for storage in a memory or remote database, or for display on a display device communicatively coupled to the phased antenna array testing system <NUM>. may also be communicatively coupled to a positioning system for controlling positions of the phased antenna array(s) <NUM> and the probe antenna(s) <NUM>.

The antenna testing control system <NUM> can further include a positioning system (not shown in <FIG>). The positioning system can be communicatively coupled to the antenna testing control system <NUM>. The positioning system can include one or more mechanical structures for mechanically supporting the phased antenna array <NUM> or the probe antenna(s) <NUM>. The positioning system can include a motor, wheels, or other mechanical components to cause the phased antenna array <NUM> or the probe antenna(s) <NUM> to automatically move between different positions or along a predefined path. For example, the positioning system can receive instructions (or signals indicative of instructions) from the antenna testing control system <NUM> and cause the phased antenna array <NUM> or the probe antenna(s) <NUM> to move between different predefined positions or along a predefined path, for example, as described above.

Referring to <FIG>, a flowchart illustrating a method <NUM> of testing phased antenna arrays is shown, according to inventive concepts of this disclosure. In brief overview, the method <NUM> can include positioning a phased antenna array and an antenna probe at relative positions with respect to each other with one of them acting as a transmitting antenna and the other acting as a receiving antenna (BLOCK <NUM>), and causing the transmitting antenna to radiate a plurality of electromagnetic waves sequentially (BLOCK <NUM>). The method <NUM> can include causing the phased antenna array to operate, during transmission of each electromagnetic wave of the plurality of electromagnetic waves, according to a corresponding configuration scheme (BLOCK <NUM>), receiving, by the receiving antenna, responsive to each radiated electromagnetic wave, and one or more corresponding receive radio frequency (RF) signals (BLOCK <NUM>). The method <NUM> can include determining, for each antenna element of the plurality of antenna elements, a corresponding signal response using the receive RF signals (BLOCK <NUM>), and determining one or more performance parameters of the phased antenna array using the determined signal responses for the plurality of antenna elements (BLOCK <NUM>).

The method <NUM> can include positioning a phased antenna array <NUM> and an antenna probe <NUM> at relative positions with respect to each other with one of them acting as a transmitting antenna and the other acting as a receiving antenna (BLOCK <NUM>). During the process of testing the phased antenna array <NUM>, the phased antenna array <NUM> can act a transmitting antenna (while the probe antenna <NUM> can act as the receiving antenna) or as a receiving antenna (while the probe antenna <NUM> can act as the transmitting antenna). Under the principal of reciprocity, the receive and transmit properties of the phased antenna array <NUM> are identical. For instance, the radiation pattern of the phased antenna array <NUM> is the same in the transmit mode and the receive mode. Accordingly, when measuring the performance parameters of the phased antenna array <NUM>, the phased antenna array can be arranged to operate as the transmitting antenna or the receiving antenna.

The antenna testing control system <NUM> can include, or can have access to, a testing schedule (or testing plan). The testing schedule can include indications of which entity among the phased antenna array <NUM> and the probe antenna <NUM> to act as the transmitting antenna and which entity to act as the receiving entity, the number of probe antennas <NUM> used, the relative locations of the phased antenna array <NUM> and the probe antenna(s) <NUM>, a sequence of transmit RF signals to be transmitted (e.g., as radiated electromagnetic waves), timing information (e.g., time of transmission of each transmit RF signal or time intervals between successive transmissions of transmit RF signals), a plurality of configuration schemes of the phased antenna array, motion information (e.g., where and/or when the probe antenna <NUM> or the phased antenna array <NUM> is/are to be moved), or a combination thereof. The antenna testing control system <NUM> can include, or can have access to, indications of properties of the probe antenna <NUM> (e.g., performance parameters, geometry parameters such as size and shape, type of probe antenna <NUM>, or a combination thereof). The antenna testing control system <NUM> can include, or can have access to, indications of design properties of the phased antenna array <NUM>, such as the number of antenna elements <NUM> in the phased antenna array <NUM>, the arrangement of the antenna elements <NUM> (e.g., number of rows and columns in the array and the number of antenna elements in each row or column), the spacing between the antenna elements <NUM>, positions of the antenna elements in the three-dimensional space, the orientations of the antenna elements, the shape of the phased antenna array <NUM> (e.g., planar or curved), or a combination thereof.

At the start of the process of testing the phased antenna array <NUM>, a user (e.g., a technician) may manually position or mount the phased antenna array <NUM> and the probe antenna <NUM> on corresponding mechanical support elements. The mechanical support elements can be positioned (e.g., fixed) at predefined testing positions. The positions of the mechanical support elements can be adjustable, and the antenna testing control system <NUM> can instruct the positioning system to move probe antenna <NUM>, the phased antenna array <NUM>, or the corresponding mechanical support elements to predefined positions at which the phased antenna array <NUM> and the probe antenna <NUM> are to be tested. The phased antenna array <NUM> can be positioned to face the probe antenna <NUM> (or one of the probe antennas <NUM> if more than one is used), for example, as illustrated in <FIG>.

Positioning the probe antenna <NUM> can include positioning the probe antenna <NUM> at a near field location relative to the phased antenna array <NUM>. For instance, the distance between the phased antenna array <NUM> and the probe antenna <NUM> can be less than the dominant wavelength λ of the transmitted RF signal (or radiated electromagnetic wave), less than <NUM>×λ, less than <NUM>×λ, or less than <NUM>×λ. Such arrangement can allow for using a relatively small antenna testing chamber <NUM>. In some cases, the user or the positioning system may position the probe antenna <NUM> at a far field location relative to the phased antenna array <NUM>. In such cases, the distance between the phased antenna array <NUM> and the probe antenna <NUM> may be, for example, greater than <NUM>×λ, greater than <NUM>×λ, or greater than some other predefined distance.

Positioning the probe antenna <NUM> can include positioning a single dual polarized probe antenna <NUM> or positioning at least two probe antennas <NUM> with distinct polarizations (e.g., including one horizontally polarized probe antenna and one vertically polarized probe antenna) as discussed above with regard to <FIG>. For instance, the user or the positioning system can position a pair of antennas <NUM>-<NUM> and <NUM>-<NUM> that are distinctly polarized or a plurality of such pairs as discussed above with regard to <FIG>. Using a dual polarized probe antenna <NUM> or a pair of distinctly polarized probe antennas, such as probe antennas <NUM>-<NUM> and <NUM>-<NUM> of <FIG>, can allow for assessing the co-polarized and cross-polarized response or performance of the phased antenna array <NUM>.

Positioning the probe antenna <NUM> can include positioning a plurality or probe antennas <NUM> at different positions relative to the phased antenna array <NUM> as discussed above with regard to <FIG>. The plurality of probe antennas may include one or more n-tuples each of which associated with n distinct operating center frequencies f<NUM>, f<NUM>,. , fn, as discussed above with regard to <FIG>. Using a plurality of probe antennas operating at various center frequencies allows for assessing the performance parameters of the phased antenna array <NUM> over a relatively wide frequency band. For example, when using a single probe antenna <NUM>, the testing of the phased antenna array <NUM> is constrained to the operating frequency band of that probe antenna <NUM>. In some cases, the probe antenna(s) <NUM> and/or the phased antenna array <NUM> may be configured to move as discussed above with regard to <FIG>.

The method <NUM> can include causing the transmitting antenna to radiate a plurality of electromagnetic waves sequentially (BLOCK <NUM>). The antenna testing control system <NUM> can send instructions to the transmitting antenna (the phased antenna array <NUM> or the probe antenna(s) <NUM>) to cause the transmitting antenna to radiate each of the plurality of electromagnetic waves, for example, according to the testing schedule. The antenna testing control system <NUM> may send a separate instruction or command for each electromagnetic wave to be radiated by the transmitting antenna, or send one instruction commanding the transmitting antenna to transmit or radiate the electromagnetic waves according to a specified time schedule. The plurality of electromagnetic waves may correspond to a single transmit RF signal or a plurality of distinct transmit RF signals (e.g., transmit RF signals associated with distinct bandwidths or center frequencies). For example radiating the plurality of electromagnetic waves may include the transmitting antenna transmitting a single transmit RF signal repeatedly at multiple time instances, transmitting time-shifted versions of the single transmit RF signal at the multiple time instances, or transmitting distinct transmit RF signals at the multiple time instances. In general, the antenna testing control system <NUM> can control the transmit RF signal(s) to be transmitted by the transmitting antenna, the radiation time of each electromagnetic wave, the order according to which the plurality of electromagnetic waves are transmitted, or a combination thereof.

In the case where multiple probe antennas <NUM> acting as transmitting antennas are used (e.g., as discussed with regard to <FIG>, <FIG> and <FIG>), the probe antennas <NUM> may transmit simultaneously or sequentially, one at a time. Also, if a moving probing antenna <NUM> (e.g., as discussed with regard to <FIG>) is used as the transmitting antenna, the probe antenna <NUM> may perform one or more transmissions while in one location, move to another location to perform one or more other transmissions, then to a third location and so on and so forth. The probe antenna <NUM> may transmit (or radiate) electromagnetic waves while moving. The antenna testing control system <NUM> can have access to the location of the moving probe antenna <NUM> (or the location of a moving phased antenna array <NUM>) at each instance an electromagnetic wave is radiated by the transmitting antenna or received by the receiving antenna.

The method <NUM> can include causing the phased antenna array <NUM> to operate, during transmission of each electromagnetic wave of the plurality of electromagnetic waves, according to a corresponding configuration scheme (BLOCK <NUM>). Each configuration scheme can be indicative of the antenna elements <NUM> of the phased antenna array <NUM> (e.g., all or a subset of the antenna elements <NUM>) to be activated, the phase shift (or time delay) to be applied to each antenna element, the power amplification to be applied to each antenna element <NUM>, or a combination thereof. Each configuration scheme can be associated with a corresponding electromagnetic wave radiated by the transmitting antenna. The antenna testing control system <NUM> may send a separate instruction to the phased antenna array <NUM> for each configuration scheme to be applied (e.g., prior to radiating the corresponding electromagnetic wave by the transmitting antenna), or may send one instruction indicative of the plurality of the configuration schemes and a time schedule according to which to apply each of the configuration schemes.

In the case where the phased antenna array <NUM> operates as the transmitting antenna, the phased antenna array <NUM> may apply or implement each configuration scheme prior to radiating the corresponding electromagnetic wave. For instance, the phased antenna array <NUM> can receive an indication of a transmit RF signal and an indication of a configuration scheme. The phased antenna array <NUM> can apply the configuration scheme (e.g., by activating one or more antenna elements <NUM>, applying to one or more antenna elements <NUM> corresponding phase shifts or time delays, applying to one or more antenna elements <NUM> corresponding power amplifications, or a combination thereof), and transmit the transmit RF signal by each of the active antenna elements <NUM>. The electromagnetic wave radiated or transmitted by the phased antenna array <NUM> can be the sum of the waves radiated/transmitted by the active antenna elements <NUM>. The phased antenna array <NUM> can then apply another configuration scheme and radiate a new electromagnetic wave as each of the now active antenna elements <NUM> transmits the same (or another) transmit RF signal. The phased antenna array <NUM> can apply a different configuration scheme for each electromagnetic wave to be transmitted/radiated.

In the case where the phased antenna array <NUM> operates as the receiving antenna, the phased antenna array <NUM> may apply or implement each configuration scheme prior to (or while) the probe antenna(s) <NUM> radiating the corresponding electromagnetic wave. For instance, the antenna testing control system <NUM> can instruct the probe antenna <NUM> to transmit or radiate an electromagnetic wave (e.g., by providing an indication of a transmit RF signal) and instruct the phased antenna array <NUM> to apply a configuration scheme. The phased antenna array <NUM> can apply the configuration scheme (e.g., by activating one or more antenna elements <NUM>, applying to one or more antenna elements <NUM> corresponding phase shifts or time delays, applying to one or more antenna elements <NUM> corresponding power amplifications, or a combination thereof) prior to the start of transmission or radiation of the electromagnetic wave by the probe antenna <NUM>. The phased antenna array <NUM> (or active antenna elements <NUM> thereof) can receive the radiated electromagnetic wave while operating according to the applied configuration scheme. The phased antenna array <NUM> can then apply another configuration scheme to receive another electromagnetic wave radiated or transmitted by the probe antenna <NUM>. This process can be repeated with a different (or separate) configuration scheme applied by the phased antenna array <NUM> each time. The probe antenna <NUM> can radiate or transmit the same electromagnetic wave (e.g., corresponding to the transmit RF signal) repeatedly. In other words, the plurality of electromagnetic waves transmitted by the probe antenna <NUM> can include (or represent) multiple transmissions of the same transmit RF signal at different time instances.

Causing the phased antenna array <NUM> to operate, during transmission of each electromagnetic wave of the plurality of electromagnetic waves, according to a corresponding configuration scheme can include activating the plurality of antenna elements <NUM> one at a time such that each antenna element is activated during transmission of a corresponding electromagnetic wave of the plurality of electromagnetic waves. Each configuration scheme can be indicative of a corresponding antenna element <NUM> of the plurality of antenna elements of the phased antenna array <NUM> to be activated. For instance, when operating as the transmitting antenna, the phased antenna array <NUM> may activate a first antenna element <NUM> and cause the activated first antenna element <NUM> to transmit a transmit RF signal while the reset of antenna elements <NUM> are deactivated. The phased antenna array <NUM> may then activate a second antenna element <NUM> (while deactivating the first antenna element <NUM>) and cause the second antenna element <NUM> to transmit the transmit RF signal (or another transmit RF signal). The phased antenna array <NUM> may continue activating the antenna elements <NUM> one at a time and causing the activated antenna element <NUM> to transmit the transmit RF signal (or a corresponding transmit RF signal), for example, until all antenna elements <NUM> of the phased antenna array <NUM> have been activated and transmitted transmit RF signal(s).

When operating as the receiving antenna, the phased antenna array <NUM> may activate (e.g., based on instruction or command from the antenna testing control system <NUM>) an antenna element <NUM> such that the activated antenna element <NUM> receives a first electromagnetic wave radiated by the probe antenna <NUM>. The phased antenna array <NUM> may then activate another antenna element <NUM> (while deactivating the previously activated antenna element <NUM>) such that the now activated antenna element <NUM> receives a second electromagnetic wave radiated by the probe antenna <NUM>. The phased antenna array <NUM> may continue activating the antenna elements <NUM> one at a time and having each activated antenna element <NUM> receive an electromagnetic wave radiated by the probe antenna <NUM>, for example, until all antenna elements <NUM> of the phased antenna array <NUM> have been activated.

Causing the phased antenna array <NUM> to operate, during transmission of each electromagnetic wave of the plurality of electromagnetic waves, according to a corresponding configuration scheme can include the phased antenna array <NUM> (e.g., based on instruction(s) or command(s) from the antenna testing control system <NUM>) phase steering the plurality of antenna elements <NUM>, during transmission of each electromagnetic wave, according to a respective phase coding scheme. Each phase coding scheme can define a corresponding set of phase shifts (or a corresponding set of time delays) applied to the plurality of antenna elements <NUM> during transmission of the corresponding electromagnetic wave. That is, each phase coding scheme can define for each antenna element <NUM> a corresponding phase shift (or a corresponding time delay) according to which that antenna element <NUM> is to operate. Each phase coding scheme may also define a set of power amplifications applied to the plurality of antenna elements <NUM> during transmission of the corresponding electromagnetic wave. That is, each phase coding scheme can define for each antenna element <NUM> a corresponding power amplification according to which that antenna element <NUM> is to operate.

For instance, when operating as the transmitting antenna, the phased antenna array <NUM> can phase steer the antenna elements <NUM> according to a first phase coding scheme and cause the antenna elements <NUM> to transmit a transmit RF signal while operating according to the first phase coding scheme. As such, the antenna elements <NUM> can simultaneously transmit various time delayed (or phase shifted) versions of the transmit RF signal that add up to form an electromagnetic wave radiated by the phased antenna array. The phased antenna array <NUM> can phase steer the antenna elements <NUM> according to a second phase coding scheme and cause the antenna elements <NUM> to transmit the transmit RF signal (or another transmit RF signal) while operating according to the second phase coding scheme. The phased antenna array <NUM> can continue phase steering the antenna elements <NUM> and causing the antenna elements <NUM> to transmit the transmit RF signal until all phase coding schemes are applied to the antenna elements <NUM>. By applying various phase coding schemes when transmitting the transmit RF signal(s), the phased antenna array <NUM> can radiate a plurality of electromagnetic waves sequentially. The electromagnetic waves radiated by the phased antenna array <NUM> may be different from each other, for example, when distinct phase coding schemes are applied to the antenna elements <NUM>.

When operating as the receiving antenna, the phased antenna array <NUM> can phase steer the antenna elements <NUM> according to a first phase coding scheme to receive an electromagnetic wave radiated by the probe antenna <NUM>. While all antenna elements <NUM> are exposed to the same magnetic wave (radiated by the probe antenna <NUM>), the antenna elements <NUM> can receive different phase shifted (or time delayed) versions of the electromagnetic wave (or a corresponding RF signal) given that different phase shifts (or time delays) can be applied to separate antenna elements <NUM>. The phased antenna array <NUM> can phase steer the antenna elements <NUM> according to a second phase coding scheme to receive another electromagnetic wave radiated by the probe antenna <NUM>. The phased antenna array <NUM> can continue phase steering the antenna elements <NUM> until all phase coding schemes (e.g., of a predefined set of coding schemes) are sequentially applied to the antenna elements <NUM> to receive a plurality of electromagnetic waves sequentially radiated by the probe antenna <NUM>. The plurality of electromagnetic waves sequentially radiated by the probe antenna <NUM> may be associated with a single transmit RF signal that is repeatedly transmitted by the probe antenna <NUM>, or may be associated with distinct transmit RF signals.

In some instances, causing the phased antenna array <NUM> to operate, during transmission of each electromagnetic wave of the plurality of electromagnetic waves, according to a corresponding configuration scheme can include can include activating a group of antenna elements of the plurality of antenna elements <NUM> and phase steering the antenna elements of the activated group. For instance, the phased antenna array <NUM> (whether operating as the transmitting antenna or the receiving antenna) can activate the plurality of antenna elements <NUM> one group (e.g., block of antenna elements) at a time. The phased antenna array <NUM> can sequentially apply to each activated group of antenna elements a corresponding plurality of phase coding schemes. For example, four distinct phase coding schemes may be sequentially applied to a group of four activated antenna elements <NUM>. Each coding scheme defines the phase shifts (or time delays) and/or power amplifications to be applied to the antenna elements of the corresponding group of active antenna elements. Each configuration scheme can define a group of antenna elements to be activated and a phase coding scheme to be applied to that group of antenna elements. This approach, where each configuration scheme defines a corresponding group (or block) of antenna elements to be activated and a corresponding phase coding scheme to be applied to the group of active antenna elements, allows for testing blocks of antenna elements separately.

The method <NUM> can include the receiving antenna (the phased antenna array <NUM> or the probe antenna <NUM>) receiving, responsive to each electromagnetic wave radiated by the transmitting antenna, a corresponding receive RF signal (BLOCK <NUM>). When the phased antenna array <NUM> operates as the receiving antenna, the receive RF signal can be a summation of signals received by active antenna elements <NUM>. For example, when the antenna elements <NUM> are activated one at a time, each receive RF signal can be a signal received by the corresponding active antenna element phased shifted (or time delayed) by any phase shift (or time delay) value associated the active antenna element <NUM> and/or amplified by an amplitude/power amplification value associated with the active antenna elements. When the antenna elements <NUM> are activated one group at a time, each receive RF signal can be a summation of phased shifted (or time delayed) and/or amplified versions (e.g., according to phase coding scheme applied to the group of antenna elements) of signals received by the corresponding active group of antenna elements. When separate phase coding schemes are applied to all the antenna elements <NUM>, one phase coding scheme at a time, each receive RF signal can be a summation of phased shifted (or time delayed) and/or amplified versions (e.g., according to the phase coding scheme applied) of signals received by the plurality of antenna elements <NUM> of the phased antenna array <NUM>. The phase shifting (or time delays) and/or the amplifications can be applied by the network of RF amplifiers and phase shifters (or time delay elements) of the phased antenna array <NUM> or by a processor (or controller) of the phased antenna array <NUM>.

When the phased antenna array <NUM> operates as the transmitting antenna, each receive RF signal can represent the signal received by the probe antenna <NUM> (responsive to a corresponding electromagnetic wave radiated by the phased antenna array <NUM>) amplified by any amplitude/power amplification associated with the probe antenna array <NUM>. In the case where multiple probe antennas <NUM> acting as receiving antennas are used (e.g., as discussed with regard to <FIG>, <FIG> and <FIG>), the probe antennas <NUM> may receive electromagnetic waves simultaneously or sequentially (e.g., activated one at a time). Also, if a moving probing antenna <NUM> (e.g., as discussed with regard to <FIG>) is used as the receiving antenna, the probe antenna <NUM> may receive one or more radiated electromagnetic waves while in one location, move to another location to receive one or more other waves, then to a third location and so on and so forth. The probe antenna <NUM> may receive electromagnetic waves while moving. The antenna testing control system <NUM> can have access to the location of the moving probe antenna <NUM> (or the location of a moving phased antenna array <NUM>) at each instance an electromagnetic wave is radiated by the transmitting antenna or received by the receiving antenna.

The method <NUM> can include determining, for each antenna element <NUM> of the plurality of antenna elements <NUM>, a corresponding signal response using the receive RF signals (BLOCK <NUM>). The antenna testing control system <NUM> can obtain a plurality of receive RF signals from the receiving antenna. As discussed above, each of the plurality of receive RF signals can be associated with a corresponding antenna element <NUM> (acting as a transmitter or as a receiver), a corresponding group of active antenna elements (acting as transmitters or as receivers) and a corresponding phase coding scheme applied to that group of active antenna elements, or a corresponding phase coding scheme applied to the plurality of antenna elements <NUM> (acting as transmitters or as a receivers) of the phased antenna array.

Assuming that the phased antenna array <NUM> has K (K is an integer) antenna elements and that N (N is an integer) receive RF signals obtained by the antenna testing control system <NUM>, each receive RF signal Yi(ω) (in the frequency domain) can be described as: <MAT> The integer i represents an index of signal transmission (or reception) events by the transmitting antenna (or the receiving antenna) or an index of the receive RF signals. The integer k represents an index of the antenna elements <NUM> of the phased antenna array <NUM>. The signal X(ω) represents the transmit RF signal (in the frequency domain) used by the transmitting antenna, and ω is the angular frequency. Each parameter Wi,k can be a complex weighting parameter associated with the k-th antenna element and defined, for example, by the phase coding scheme applied during the i-th transmission/reception event. For instance, the complex weighting parameter Wi,k can be indicative of the time delay (or phase shift) and/or power amplification applied by the phased antenna array <NUM> to the signal transmitted or received by the k-th antenna element during the i-the transmission/reception event. As used herein a transmission or reception event refers to a transmission (or a reception) of an electromagnetic wave by the transmitting antenna (or receiving antenna). The complex weighting parameters Wi,k for all k = <NUM>,. , K and all i = <NUM>,. , N are known to the antenna testing control system <NUM> since these parameters can be predefined in the configuration schemes (or phase coding schemes) applied by the phased antenna array <NUM> during the various transmission/reception events. Each parameter Ak can be a complex weighting parameter associated with the k-th antenna element that can be indicative of phase shift and signal attenuation due to the distance between the k-th antenna element and the phased antenna array, the gain of the probe antenna <NUM> at the direction of transmission or reception, the gain of the k-th antenna element at the direction of transmission or reception, or a combination thereof. For instance, the complex weighting parameter Ak can be indicative of the time delay (or phase shift) and/or power amplification applied by the phased antenna array <NUM> to the signal transmitted or received by the k-th antenna element during the i-th transmission/reception event. The complex weighting parameters Ak for k =<NUM>,. , K are the unknowns in the set of equations (<NUM>).

The formulation in the set of equations (<NUM>) illustrates that each receive RF signal Yi(ω) can be expressed, in the frequency domain, as a weighted sum of the transmit RF signal X(ω). In the case where all the antenna elements <NUM> of the phased antenna array <NUM> are activated with a distinct phase coding scheme applied by the phased antenna array <NUM> during each of the transmission/reception events, the complex weighting parameters Ak can be non-zero for all k = <NUM>,. , K, and the complex weighting parameters Wi,k can be non-zero for all i =<NUM>,. , N and all k = <NUM>,. In the case where the antenna elements <NUM> are activated one group at a time, the set of equations (<NUM>) can be re-written as <MAT> where Si represents the set of indices for the active antenna elements during the i-th transmission/reception event. In the case where the antenna elements <NUM> are activated one at a time, the set of equations (<NUM>) reduces to <MAT> where the integer q(i) represents the index of the active antenna element during the i-th transmission/reception event.

Since the transmit RF signal X(ω) and the complex weighting parameters Wi,k are already known, the antenna testing control system <NUM> can solve for the complex weighting parameters Ak using any of the sets of equations (<NUM>), (<NUM>), or (<NUM>) depending on the type of configuration schemes applied or implemented by the phased antenna array <NUM>. For example, using equation (<NUM>), the antenna testing control system <NUM> can compute Aq(i) as: <MAT> The antenna testing control system <NUM> can solve the set of equations (<NUM>) for the complex weighted parameters Ak as long as N ≥ K and the N equations (<NUM>) are linearly independent. The phase coding schemes used can be selected or designed (e.g., by the antenna testing control system <NUM>) such that the set of equations (<NUM>) are linearly independent with N ≥ K. For the set of equations (<NUM>), the antenna testing control system <NUM> can solve each subset of equations associated with a corresponding group of activated antenna elements separately given that the number of equations for each group (or block) Si of active antenna elements is greater than or equal to the number of antenna elements in that group (or block). The phase coding schemes associated with each group (or block) of antenna elements Si can be selected or designed (e.g., by the antenna testing control system <NUM>) to be greater than the number of antenna elements in that group (or block) and such that the corresponding equations (among the set of equations (<NUM>)) are linearly independent.

Once the complex weighting parameters Ak are determined, the antenna testing control system <NUM> can determine a signal response for each antenna element <NUM>. The antenna testing control system <NUM> can remove from each complex weighting parameters Ak the effect of the probe antenna gain (along the angle of arrival/departure of the received/transmitted electromagnetic wave), the time delay due to the electromagnetic wave propagation between the probe antenna and the k-th antenna element, and electromagnetic wave attenuation (if any) due to the electromagnetic wave propagation between the probe antenna and the k-th antenna element. For instance, the antenna testing control system <NUM> can compute a new set of complex weighting parameters Bk such that <MAT> where Gp(θ, ϕ) represents the gain of the probe antenna <NUM> along the angle of electromagnetic wave propagation, and the parameter ρkejωδ represents the amplitude attenuation and the phase shift due to electromagnetic propagation between the probe antenna <NUM> and the k-th antenna element. In some instances, the amplitude attenuation parameter ρk can be equal to <NUM>. The radiation pattern of the probe antenna <NUM> may be known in advance to the antenna testing control system <NUM>. For instance, a representation of the radiation pattern of the probe antenna <NUM> may be stored in a memory accessible by the antenna testing control system <NUM>. The antenna testing control system <NUM> can precompute the parameter ρkejωδ (for each antenna element with index k) based on the distance between the probe antenna <NUM> and the k-th antenna element.

The antenna testing control system <NUM> can determine the signal response for each antenna element as BkX(ω). If the phased antenna array <NUM> is acting as the transmitting antenna, the signal response BkX(ω) can be viewed as the RF signal radiated at the surface of the k-th antenna element when no weighting (e.g., as a phase shift and/or a power amplification) is applied at the phased antenna array <NUM> in association with the k-th antenna element. The complex weighting parameter Bk can be viewed as representing a phase and amplitude response of the k-th antenna element. Hence, determining a signal response for each antenna element can include determining phase and amplitude responses (or phase and amplitude parameters) for each antenna element. The phase and amplitude responses defined by complex weighting parameter Bk are independent of the probe antenna <NUM> and the distance between (or the positions of) the phased antenna array <NUM> and probe antenna <NUM>. When a complex weighting Wi,k (e.g., as phase shift and/or power amplification) is applied by the phased antenna array <NUM>, the RF signal radiated at the surface of the k-th antenna element can be equal to Wi,kBkX(ω). In the case where the phased antenna array <NUM> is acting as the receiving antenna, the signal response BkX(ω) can be viewed as the RF signal received at the surface of the k-th antenna element before any weighting (e.g., as a phase shift and/or a power amplification) is applied at the phased antenna array <NUM> in association with the k-th antenna element.

In some instances, additional equations (similar to equations (<NUM>)) can be formulated, for example, when using multiple probe antennas <NUM>. The multiple probe antennas <NUM> can be associated with distinct locations (as discussed with respect to <FIG>), distinct polarizations (as discussed with regard to <FIG>), distinct operating center frequencies (as discussed with regard to <FIG>), or a combination thereof. In such instances, a separate set of equations (similar to the set of equations (<NUM>)) can be formulated for each probe antenna <NUM>. Accordingly, the antenna testing control system <NUM> can solve multiple sets of equations and determine multiple signal responses (or multiple phase and amplitude responses) for each antenna element. For example, for a given antenna element, the antenna testing control system <NUM> can determine a signal response for each center frequency and/or for each wave polarization (e.g., Horizontal and vertical polarizations).

The method <NUM> can include determining one or more performance parameters of the phased antenna array <NUM> using the determined signal responses (or the determined phase and amplitude parameters) for the plurality of antenna elements <NUM>. For instance, the antenna testing control system <NUM> can use the determined amplitude/phase response (or amplitude and phase parameters) for each of the antenna elements <NUM> to determine a far field response of the phased antenna array <NUM>. The antenna testing control system <NUM> can use far field response of the phased antenna array <NUM> to determine the performance parameters of the phased antenna array <NUM>.

In some instances, the antenna testing control system <NUM> can use the phase/amplitude responses of the antenna elements and an average individual antenna element radiation pattern (e.g., representative of the radiation pattern of each antenna element <NUM> assuming similarly behaving antenna elements <NUM>) to determine the far field response (or radiation pattern) of the phased antenna array <NUM>. For instance, the far field response (or radiation pattern) of the phased antenna array can be computed as a weighted sum of the average individual antenna element radiation pattern scaled by the phase/amplitude responses of the antenna elements <NUM>.

Referring to <FIG>, a block diagram illustrating an approach for determining the far field response of the phased antenna array <NUM> based on amplitude/phase response (or amplitude and phase parameters) for each of the antenna elements <NUM> is shown, according to inventive concepts of this disclosure. By determining the phase/amplitude response for each antenna element, the antenna testing control system <NUM> can determine the electric (or magnetic) field and/or electric current over a closed surface <NUM> around the phased antenna array. In particular, the electric (or magnetic) field and/or electric current over the closed surface <NUM> are non-zero only over the portion <NUM> of the closed surface <NUM> that is facing (or in front of) the antenna elements <NUM> since electromagnetic waves radiated by the antenna elements <NUM> do not propagate along the sides or the back of the phased antenna array <NUM>.

According to the surface equivalence principle (or surface equivalence theorem), if the fields/currents are uniquely known over a closed surface (e.g. two of the electric field E, magnetic field H, the magnetic flux density B vector, or the current density vector J) then the fields/currents everywhere inside or outside of the volume defined by the closed surface can be uniquely identified or determined. Accordingly, the antenna testing control system <NUM> can, for example, determine the electric field E and the current density J vector based on the portion <NUM> of the closed surface <NUM> based on the determined amplitude/phase response for each antenna element <NUM> of the phased antenna array <NUM>. The antenna testing control system <NUM> can set the electric field E and the current density J vector to zero on the rest of the closed surface <NUM>. The antenna testing control system <NUM> can then apply a Fourier transform to the determined phase/amplitude responses of the antenna elements <NUM> to determine a far field response of the phased antenna array <NUM> according to the surface equivalence principle.

Referring to <FIG>, example simulation results illustrating phase/amplitude responses of the antenna elements <NUM> of the phased antenna array <NUM> are shown, according to inventive concepts of this disclosure. Each diamond shaped cell represents a corresponding antenna element <NUM> of the phased antenna array <NUM>.

Referring to <FIG>, an example far field response of the phased antenna array <NUM> determined using the antenna elements' phase/amplitude responses shown in <FIG> is shown, according to inventive concepts of this disclosure. The far field response shown in <FIG> represents a radiation pattern of the phased antenna array <NUM> along an azimuth angle range between -<NUM> and <NUM> degrees and an elevation angle range between -<NUM> and <NUM> degrees.

When the phased antenna array <NUM> applies phase shifts (or time delays) and/or power amplifications to the antenna elements <NUM> defined by the complex weighting parameters Vk (or Wi,k), for k = <NUM>,. , K, the antenna testing control system <NUM> can incorporate these complex weighting parameters into the phase/amplitude responses of the antenna elements <NUM>, for example, as VkBk (or Wi,kBk). By determining the electric (or magnetic) fields/currents over the closed surface <NUM> based on the phase/amplitude responses VkBk (or Wi,kBk), the antenna testing control system <NUM> can use the Fourier transform to determine the far field response (or radiation pattern) of the phased antenna array <NUM> when phase steered according to the complex weighting parameters Vk (or Wi,k), for k= <NUM>,.

Based on the determined radiation patter of the phased antenna array <NUM>, the antenna testing control system <NUM> can determine one or more other performance parameters of the phased antenna array including the phased antenna array gain (e.g., co-polarized gain and cross-polarized gain), the co-polarized phased antenna array directivity (e.g., co-polarized directivity and cross-polarized directivity), the phased antenna array beamwidth, the radiated power, the cross-polarization discrimination, the antenna gain-to-noise-temperature, the error vector magnitude, the adjacent channel power ratio, the pulse quality, one or more side lobe levels, signal-to-noise ratio (SNR), or a combination thereof. For instance, the antenna testing control system <NUM> can determine the peak phased antenna gain based on the peak value (at the main lobe) of radiation pattern of the phased antenna array <NUM>. To determine the co-polarized gain and cross-polarized gain, two probe antennas <NUM> with distinct polarizations (as discussed with regard to <FIG>) can be used. One probe antenna <NUM> can be polarized similar the phased antenna array <NUM> (e.g., both with horizontal polarizations) and another probe antenna with cross-polarization (e.g., vertical polarization when the phased antenna array has horizontal polarization). The antenna testing control system <NUM> can determine a co-polarized far field response and cross-polarized far field response of the phased antenna array <NUM>. The antenna testing control system <NUM> can determine the co-polarized gain using the determined co-polarized far field response, and determine the cross-polarized gain using the determined cross-polarized far field response of the phased antenna array.

The antenna testing control system <NUM> can determine the directivity as: <MAT> where F(θ, ϕ) represents the far field response of the phased antenna array <NUM> along the elevation angle θ and azimuth angle ϕ. To determine the co-polarized directivity and the cross-polarized directivity, the antenna testing control system <NUM> can evaluate equation (<NUM>) for the co-polarized far field response of the phased antenna array <NUM> and the cross-polarized far field response of the phased antenna array <NUM> separately.

The antenna beamwidth of the phased antenna array <NUM> can be defined as the half power beamwidth or the null to null beamwidth. The antenna testing control system <NUM> can determine the angular separation in which the magnitude of the radiation pattern decreases by <NUM>% (or <NUM> dB) from the peak of the main lobe in the case of the half power beamwidth. The antenna testing control system <NUM> can determine the angular separation in which the magnitude of the radiation pattern decreases zero from the peak of the main lobe in the case of the null to null beamwidth. The antenna testing control system <NUM> can determine the radiated power as the summation of the radiated powers of each of the antenna elements <NUM>. The antenna testing control system <NUM> can also determine the cross-polarization discrimination, the antenna gain-to-noise-temperature, the error vector magnitude, the adjacent channel power ratio, the pulse quality, one or more side lobe levels, and the signal-to-noise ratio (SNR) using the determined radiation pattern(s) of the phased antenna array and/or the determined phase/amplitude responses (or phase/amplitude parameters) of the phased antenna array <NUM>.

Referring to <FIG>, a flowchart illustrating another method <NUM> of testing phased antenna arrays is shown, according to inventive concepts of this disclosure. In brief overview, the method <NUM> can include positioning a phased antenna array and an antenna probe at relative positions with respect to each other with one of them acting as a transmitting antenna and the other acting as a receiving antenna (BLOCK <NUM>), and applying to antenna elements of the phased antenna array phase shifts to compensate for differences in signal propagation times between the antenna probe the antenna elements (BLOCK <NUM>). The method <NUM> can include causing the transmitting antenna to radiate an electromagnetic wave (BLOCK <NUM>), receiving a RF signal responsive to radiating the electromagnetic wave (BLOCK <NUM>), and determining one or more performance parameters of the phased antenna array using the receive d RF signal (BLOCK <NUM>).

The step <NUM> of method <NUM> can be similar to step <NUM> of method <NUM> described above. The method <NUM> can also include the antenna testing control system causing the phased antenna array <NUM> to apply to the antenna elements <NUM> phase shifts to compensate for differences in signal propagation times between the antenna probe <NUM> and the antenna elements <NUM> (BLOCK <NUM>). That is, the phase shifts are applied such that signals transmitted by the antenna elements <NUM> add up constructively at the receiving probe antenna <NUM>, or signals received by the antenna elements <NUM> add up constructively at the receiving phased antenna array <NUM>. For instance, the phase shift (or time delay) applied to each antenna element may be selected (e.g., by the antenna testing control system <NUM>) to compensate for the propagating time between the probe antenna and that antenna element <NUM>. Applying phase shifts to the antenna elements <NUM> to compensate for differences in signal propagation times between the antenna probe <NUM> and the antenna elements <NUM> can cause the peak of the main lobe of the phased antenna array <NUM> to be aligned with the probe antenna <NUM>.

The steps <NUM> and <NUM> of method <NUM> can be similar to the steps <NUM> and <NUM> of method <NUM> described above, except that the antenna testing control system <NUM> can cause the phased antenna array <NUM> to increment (or modify) the phase shifts already applied to antenna elements <NUM> by a common phase offset, and perform another transmission reception event. Such phase offset can cause the peak of the main lobe (or the main lobe) of the phased antenna array <NUM> to rotate by a predefined angle. The antenna testing control system <NUM> can repeat incrementing or modifying the phase shifts (or time delays) applied to the antenna elements <NUM> by the same (or another) phase offset value or (or offset calibration) to further tilt (or rotate) the radiation pattern of the phased antenna array <NUM>. For example, referring back to <FIG>, the offset calibrations can cause the peak of the main lobe (or the main lobe) of the phased antenna array <NUM> to be aligned with a new position point <NUM> with each offset calibration. Such approach can allow for determining the far field response at various angles. For each receive RF signal (associated with a corresponding offset calibration), the gain of the phased antenna array <NUM> (or the far field response) along an orientation angle (with respect to the peak of the main lobe of the radiation pattern of the phased antenna array <NUM>) associated with calibrated phases of the antenna elements can be determined as <MAT> where GA is the gain (or far field response) of the phased antenna array along the orientation angle, GR is the gain (or far field response) along the same orientation angle of a reference (or standard gain) antenna, PA is received power of the phased antenna array <NUM>, and PR is the received power of the reference antenna. The gain GR and the power and PR for each orientation angle can be known to (or accessible to) the antenna testing control system <NUM>, and the power PA f the phased antenna array <NUM> can be computed for each phase calibration (or orientation of the radiation pattern of the phased antenna array <NUM>) based on, for example, the corresponding received (or transmitted) signal by the phased antenna array. Accordingly, the antenna testing control system <NUM> sample the radiation pattern of the phased antenna array <NUM> by applying the phase offset calibrations.

Using the measured samples of the radiation pattern (or far field response) of the phased antenna array <NUM>, the antenna testing control system <NUM> can determine one or more performance parameters of the phased antenna array <NUM>. For example, the antenna testing control system <NUM> can determine the performance parameters including the phased antenna array gain (e.g., co-polarized gain and cross-polarized gain), the co-polarized phased antenna array directivity (e.g., co-polarized directivity and cross-polarized directivity), the phased antenna array beamwidth, the radiated power, the cross-polarization discrimination, the antenna gain-to-noise-temperature, the error vector magnitude, the adjacent channel power ratio, the pulse quality, one or more side lobe levels, signal-to-noise ratio (SNR), or a combination thereof, using the measured radiation pattern (or samples thereof) as discussed above with regard to <FIG>. By applying the phase offset calibrations, the antenna testing control system <NUM> can determine the far field response of the phased antenna array <NUM> without necessarily scanning the beam anywhere near the probe antenna <NUM>.

Referring to <FIG>, a block diagram of a phased antenna array testing system <NUM> is shown, according to inventive concepts of this disclosure. While conventional testing systems typically employ a network analyzer which is considered as a complex and expensive equipment, the system <NUM> can include a first low noise block (LNB) down-converter <NUM> (e.g., a circuit) to down-convert signals received from phased antenna array <NUM> to an intermediate frequency. The system <NUM> can include a first DVB-T USB device <NUM> and a computing device <NUM>. The first DVB-T USB device <NUM> can couple the first (LNB) down-converter <NUM> to the computing device <NUM>.

The computing device <NUM> can include, for example, a laptop, a desktop, a hardware server, a tablet, a mobile device, or a printed circuit board. The computing device <NUM> can be configured (e.g., through executable software instructions) to perform tasks and processes described above as performed by the antenna testing control system <NUM>, such as controlling and monitoring phase steering of the phased antenna array, processing receive RF signals, determining performance parameters of the phased antenna array, or a combination thereof. The computing device <NUM> can be communicatively coupled through a second DVB-T USB device <NUM> and a second low noise block (LNB) down-converter <NUM> (e.g., a circuit) to the probe antenna <NUM>. The second low noise block (LNB) down-converter <NUM> can down-convert receive signals obtained by the probe antenna <NUM> to an intermediate frequency.

The system <NUM> can include a signal generator circuit <NUM> for generating, for example, baseband transmit RF signals. The signal generator circuit <NUM> can be communicatively coupled to the computing device <NUM>, for example, to receive instructions from the computing device <NUM> and/or provide copies of generated baseband transmit RF signals to the computing device <NUM>. The signal generator circuit (or device) <NUM> can be communicatively coupled to the transmitting antenna (phased antenna array <NUM> or the probe antenna <NUM> through an up-converter block (or circuit) <NUM>. The up-converter block <NUM> can up-convert signals provided by the signal generator circuit <NUM> to an intermediate (or high) frequency, and provided the up-converted signals to the transmitting antenna.

Referring to <FIG>, a block diagram of another phased antenna array testing system <NUM> is shown, according to inventive concepts of this disclosure. The system <NUM> can be similar to the system <NUM> except that the computing device <NUM> in system <NUM> is replaced with a USB hub <NUM> that is communicatively coupled the phased antenna array <NUM>, and the phased antenna array includes a processor <NUM> that is configured to perform the tasks or operating performed by the computing device <NUM> in system <NUM>. Specifically, the processor <NUM> can be configured (e.g., through executable software instructions) to perform tasks and processes described above as performed by the antenna testing control system <NUM>, such as controlling and monitoring phase steering of the phased antenna array <NUM>, processing receive RF signals, determining performance parameters of the phased antenna array <NUM>, or a combination thereof.

Claim 1:
A method of testing phased antenna arrays, the method comprising:
positioning a phased antenna array including a plurality of antenna elements and a probe antenna of a plurality of probe antennas at relative positions with respect to each other, either the phased antenna array acting as a transmitting antenna and the probe antenna acting as a receiving antenna, or the probe antenna acting as the transmitting antenna and the phased antenna array acting as the receiving antenna; causing the transmitting antenna to radiate a plurality of electromagnetic waves sequentially;
causing the phased antenna array to operate,
during transmission of each electromagnetic wave of the plurality of electromagnetic waves according to a corresponding configuration scheme,
the corresponding configuration scheme defining at least one of a respective set of antenna elements that are active during the transmission of the electromagnetic wave, or a respective set of phase shifts or time delays that are applied to the plurality of antenna elements during the transmission of the electromagnetic wave;
receiving, by the receiving antenna,
responsive to each radiated electromagnetic wave, a corresponding receive radio frequency (RF) signal; determining, for each antenna element of the plurality of antenna elements, corresponding amplitude and phase parameters using the receive RF signals corresponding to the plurality of electromagnetic waves;
and determining one or more performance parameters of the phased antenna array using the determined amplitude and phase parameters for the plurality of antenna elements, characterised in that the plurality of probe antennas are operating at different center frequencies and are positioned at a near field location relative to the phased antenna array.