# Patent

## Title
Automatic high-resolution adaptive beam-steering

## Abstract

A method includes pointing a receive beam of a retro-directive antenna array attracted to a jammer circuit instead of a remote transmitter away from the jammer circuit toward the remote transmitter by a first angle based on coarse manual means therefor implemented in electronic circuitry associated with the retro-directive antenna array. The electronic circuitry includes a number of mixers, each of which is configured to mix a Local Oscillator (LO) signal generated from a Voltage Controlled Oscillator (VCO) with a signal received at an antenna element of the retro-directive antenna array. The method also includes automatically fine pointing the receive beam toward the remote transmitter by a second angle following the coarse pointing thereof by the first angle such that the receive beam exactly points to, and tracks, the remote transmitter. The automatic fine pointing is effected through a secondary automatic servo loop implemented in the electronic circuitry.

## Background
CLAIM OF PRIORITY
This application is a conversion application of the U.S. provisional patent application No. 61/801,765 titled AUTOMATIC HIGH-RESOLUTION ADAPTIVE BEAM-STEERING filed on Mar. 15, 2013.
FIELD OF TECHNOLOGY
This disclosure generally relates to beam-steering and, more specifically, to a method, a circuit and/or a system of automatic high-resolution adaptive beam-steering.
BACKGROUND
Modern systems such as wireless, phased array, communication, radar, Global Positioning System (GPS) and signal gathering systems may require control and/or maintenance of direction of a beam. The aforementioned systems may require costly physical alignment of antenna systems thereof; in the case of electronic beam-steering antenna systems, a high level of circuit and processing complexity may be required, in addition to constant monitoring.
A servo system utilized to determine the direction of a remote transmitter and then to transmit Radio Frequency (RF) signals back at the remote transmitter may require complete down-conversion and digital signal processing, which are time consuming and costly in terms of circuitry and power. Moreover, such a system may be sensitive to jamming from unwanted transmitters.
SUMMARY
Disclosed are a method, a circuit and/or a system of automatic high-resolution adaptive beam-steering.
In one aspect, a method includes pointing a receive beam of a retro-directive antenna array including a number of antenna elements attracted to a jammer circuit instead of a remote transmitter away from the jammer circuit toward the remote transmitter by a first angle based on coarse manual means therefor implemented in electronic circuitry associated with the retro-directive antenna array. The electronic circuitry includes a number of mixers, each of which is configured to mix a Local Oscillator (LO) signal generated from a Voltage Controlled Oscillator (VCO) of a coupled VCO array including a number of VCOs with a signal received at an antenna element.
The method also includes automatically fine pointing the receive beam toward the remote transmitter by a second angle following the coarse pointing thereof by the first angle such that the receive beam exactly points to, and tracks, the remote transmitter. The automatic fine pointing is effected through a secondary automatic servo loop implemented in the electronic circuitry associated with the retro-directive antenna array.
In another aspect, a beam-steering system includes a retro-directive antenna array including a number of antenna elements. A receive beam of the retro-directive antenna array is attracted to a jammer circuit instead of a remote transmitter. The beam-steering system also includes coarse manual means implemented in electronic circuitry associated with the retro-directive antenna array for pointing the receive beam away from the jammer circuit toward the remote transmitter by a first angle. The electronic circuitry includes a number of mixers, each of which is configured to mix a LO signal generated from a VCO of a coupled VCO array including a number of VCOs with a signal received at an antenna element.
The beam-steering system further includes a secondary automatic servo loop implemented in the electronic circuitry associated with the retro-directive antenna array for automatic fine pointing of the receive beam toward the remote transmitter by a second angle following the coarse pointing thereof by the first angle such that the receive beam exactly points to, and tracks, the remote transmitter.
In yet another aspect, a wireless communication system includes a remote transmitter, a jammer circuit and a beam-steering system. The beam-steering system includes a retro-directive antenna array including a number of antenna elements. A receive beam of the retro-directive antenna array is attracted to the jammer circuit instead of the remote transmitter. The beam-steering system also includes coarse manual means implemented in electronic circuitry associated with the retro-directive antenna array for pointing the receive beam away from the jammer circuit toward the remote transmitter by a first angle. The electronic circuitry includes a number of mixers, each of which is configured to mix a LO signal generated from a VCO of a coupled VCO array including a number of VCOs with a signal received at an antenna element.
The beam-steering system further includes a secondary automatic servo loop implemented in the electronic circuitry associated with the retro-directive antenna array for automatic fine pointing of the receive beam toward the remote transmitter by a second angle following the coarse pointing thereof by the first angle such that the receive beam exactly points to, and tracks, the remote transmitter.
Other features will be apparent from the accompanying drawings and from the detailed description that follows.



BRIEF DESCRIPTION OF THE FIGURES
Example embodiments are illustrated by way of example and not limitation in the figures of the accompanying drawings, in which like references indicate similar elements and in which:
FIG. 1 is a schematic view of a beamforming system involving Local Oscillator (LO) scanned arrays.
FIG. 2 is a schematic view of directivity of a retro-directive array of the beamforming system of FIG. 1 being servoed to a jammer circuit instead of a remote transmitter.
FIG. 3 is a schematic view of controlling direction of a beam even in the presence of jammer signals in the beamforming system of FIG. 1, according to one or more embodiments.
FIG. 4 is a process flow diagram detailing operations involved in automatic high-resolution adaptive beam-steering in the beamforming system of FIG. 1, according to one or more embodiments.



Other features of the present embodiments will be apparent from the accompanying drawings and from the disclosure that follows.
DETAILED DESCRIPTION
Example embodiments, as described below, may be used to provide a method, a circuit and/or a system of automatic high-resolution adaptive beam-steering. Although the present embodiments have been described with reference to specific example embodiments, it will be evident that various modifications and changes may be made to these embodiments without departing from the broader spirit and scope of the various embodiments.
Beamforming may be a technique for electronically setting a direction of a Radio Frequency (RF) beam using fixed arrays of antenna apertures or antenna elements. The aforementioned antenna arrays may be one-dimensional, two-dimensional or three-dimensional. The electronic pointing of the RF beam may be performed for either transmission or reception of signals. Beamforming, or electronic direction setting of the RF beam, may typically be achieved through the introduction of differential phase shifts in signal paths coupled to each of the antenna apertures or antenna elements.
It should be noted that exemplary embodiments to be discussed herein are to be placed within the context of a receiver (e.g., wireless receiver), where Local Oscillator (LO) signal generation is required.
A common technique to introduce the requisite phase shift in the signal path may involve generation of LO signals to mixers located in the signal paths. The aforementioned configuration may be called an LO scanned array. FIG. 1 shows a beamforming system 100 involving LO scanned arrays; LO scanned arrays may also be utilized to sense the direction from which a transmitter 102 is radiating energy. The antenna system including antenna array 106 and antenna electronics 107 may be utilized to reflect back the incident RF radiation in the direction of the source transmitter 102. The aforementioned antenna array 106 may be called a retro-directive array. FIG. 1 shows the automatic adaptive alignment of the receive beam (e.g., receive beam 160) toward the direction (e.g., through rotating an angle β) of the transmitted RF signal.
In the LO scanned arrays of FIG. 1, LO signals 108 with differential phases may be generated, and the differential phase LO signals 108 may be input to mixers 111 located in the signal paths. Antenna array 106 may be utilized in beam-steering or directing and/or focusing of transmitted/received signals. By directing the energy from or concentrating the energy incoming thereto, a higher efficiency may be achieved compared to a standard antenna implementation. This may result in the capability to transmit or receive signals corresponding to or from more distant receiving or transmitting radios, as discussed above.
A voltage controlled oscillator (VCO) 101 (see, e.g., FIGS. 1-3) may be an electronic oscillator configured to vary oscillation frequency thereof based on a voltage input. FIGS. 1-3 serve to describe the receiver (e.g., wireless receiver) context in which exemplary embodiments discussed herein may be practiced. The function of VCO 101 in LO signal generation (e.g., LO signal 108) as applied to receivers is well known to one skilled in the art. In order to generate differential phase LO signals, a coupled VCO array may be utilized. FIG. 1 shows beamforming system 100 including a coupled VCO array 150. Here, coupled VCO array 150 may include two or more VCOs 101 mutually injection locked to each other. Injection locking may be the state in which the two or more VCOs 101 exchange oscillatory energy sufficient enough to lock to a same frequency. Injection locking may be accomplished based on coupling VCOs 101 together through a bidirectional coupling circuit (e.g., resistor 103; other bidirectional coupling circuits 103 may also be used instead).
The outputs of mixing of LO signals 108 with signals from antenna elements of antenna array 106 may be combined at combiner 112 (e.g., a combiner circuit). There may be various ways to sense the direction of the remote transmitter 102, and to servo the LO phase relationships in the LO scanned array discussed above to better receive the remote signal, or to transmit energy back in the direction of the remote signal. The aforementioned ways may also be employed to track a remote transmitter (e.g., transmitter 102) in motion relative to the retro-directive array discussed above.
A high power jammer circuit may, however, deceive the retro-directive array into servoing directivity thereof to the jammer circuit instead of the remote transmitter 102. FIG. 2 shows the abovementioned deception effected through a high power jammer 202 (or, another transmitter).
FIG. 3 shows controlling the direction of receive beam 160 even in the presence of jammer signals to allow receive beam 160 to automatically align in the direction of the remote transmitter 102, according to one or more embodiments. In one or more embodiments, the aforementioned alignment may be enhanced to a fine resolution, as will be discussed below.
As such, in one or more embodiments, a hybrid system providing for both manual and automatic means to electronically point antenna array 106 may be realized, as shown in FIG. 3. First, in one or more embodiments, a manual means 304 of pointing antenna array 106 may be implemented (e.g., through antenna electronics 107) to ignore all jammer signals (e.g., from another remote transmitter or a jammer 302) and to move the pointing of antenna array 106 through angle α (a first angle). In one or more embodiments, once the manual pointing is done, a secondary automatic servo loop 306 (e.g., also implemented in antenna electronics 107 in FIG. 3) may be engaged to point antenna array 106 through angle β (a second angle) such that receive beam 160 points to, and tracks, desired transmitter 102.
The abovementioned pointing operations may be classified under coarse manual pointing and automatic fine pointing. In one or more embodiments, here, the retro-directive array may not react to jammer 302 because the manual pointing controls an approximate pointing of the array in a direction away from jammer 302. In one or more embodiments, the control capability of the secondary automatic servo pointing may be limited to operation over a limited pointing angle (e.g., the second angle); the aforementioned limiting may be effected through secondary automatic servo loop 306.
Thus, exemplary embodiments may provide for automatic high-resolution adaptive beam-steering that is effective even in the presence of jammer signals. It will be appreciated that concepts disclosed herein may also be applied to two-dimensional or three-dimensional arrays of coupled VCOs 101, in addition to one-dimensional arrays thereof.
FIG. 4 shows a process flow diagram detailing operations involved in automatic high-resolution adaptive beam-steering, according to one or more embodiments. In one or more embodiments, operation 402 may involve pointing receive beam 160 of retro-directive antenna array 106 including a number of antenna elements attracted to a jammer circuit (e.g., jammer 302) instead of a remote transmitter (e.g., transmitter 102) away from the jammer circuit toward the remote transmitter by a first angle based on coarse manual means 304 therefor implemented in electronic circuitry (e.g., antenna electronics 107) associated with retro-directive antenna array 106. In one or more embodiments, the electronic circuitry includes a number of mixers 111, each of which is configured to mix an LO signal 108 generated from a VCO 101 of coupled VCO array 150 including a number of VCOs 101 with a signal received at an antenna element.
In one or more embodiments, operation 404 may then involve automatically fine pointing receive beam 160 toward the remote transmitter by a second angle following the coarse pointing thereof by the first angle such that the receive beam exactly points to, and tracks, the remote transmitter. In one or more embodiments, the automatic fine pointing may be effected through secondary automatic servo loop 306 implemented in the electronic circuitry associated with retro-directive antenna array 106.
Although the present embodiments have been described with reference to specific example embodiments, it will be evident that various modifications and changes may be made to these embodiments without departing from the broader spirit and scope of the various embodiments. Accordingly, the specification and drawings are to be regarded in an illustrative rather than a restrictive sense.

## Claims

1. A method comprising:
implementing, through electronic circuitry of a retro-directive antenna array comprising a plurality of antenna elements, a capability to ignore a jammer circuit by the retro-directive antenna array during presence of the jammer circuit, the electronic circuitry further comprising a plurality of mixers, each of which is configured to mix a Local Oscillator (LO) signal generated from a Voltage Controlled Oscillator (VCO) of a coupled VCO array comprising a plurality of VCOs with a signal received at an antenna element;
in the presence of the jammer circuit, moving, based on the implemented capability through the electronic circuitry, pointing of a receive beam of the retro-directive antenna array toward a remote transmitter and away from the jammer circuit; and
automatically fine pointing the receive beam toward the remote transmitter following the moving thereof such that the receive beam exactly points to, and tracks, the remote transmitter, the automatic fine pointing being effected through a secondary automatic servo loop implemented in the electronic circuitry associated with the retro-directive antenna array.

2. The method of claim 1, comprising regarding, through the electronic circuitry, another remote transmitter as the jammer circuit during the moving of the pointing of the receive beam.

3. The method of claim 1, further comprising injection locking two or more VCOs of the coupled VCO array to each other.

4. The method of claim 1, further comprising coupling a VCO of the coupled VCO array to another VCO thereof through a bidirectional coupling circuit.

5. The method of claim 1, comprising providing one of: a one-dimensional, a two-dimensional and a three-dimensional VCO array as the coupled VCO array.

6. The method of claim 1, comprising limiting the automatic fine pointing to operation over a limited pointing angle.

7. The method of claim 1, further comprising combining outputs of the plurality of mixers as part of beamforming with the retro-directive antenna array.

8. A beam-steering system comprising:
a retro-directive antenna array comprising a plurality of antenna elements, a receive beam of the retro-directive antenna array being attracted to a jammer circuit instead of a remote transmitter;
electronic circuitry associated with the retro-directive antenna array implemented with a capability to ignore the jammer circuit, and, in accordance therewith, move pointing of the receive beam away from the jammer circuit toward the remote transmitter, the electronic circuitry comprising a plurality of mixers, each of which is configured to mix a LO signal generated from a VCO of a coupled VCO array comprising a plurality of VCOs with a signal received at an antenna element; and
a secondary automatic servo loop implemented in the electronic circuitry associated with the retro-directive antenna array for automatic fine pointing of the receive beam toward the remote transmitter following the moving of the pointing of the receive beam toward the remote transmitter such that the receive beam exactly points to, and tracks, the remote transmitter.

9. The beam-steering system of claim 8, wherein the electronic circuitry is configured to regard another remote transmitter as the jammer circuit during the moving of the pointing of the receive beam.

10. The beam-steering system of claim 8, wherein two or more VCOs of the coupled VCO array are configured to be injection locked to each other.

11. The beam-steering system of claim 8, wherein a VCO of the coupled VCO array is configured to be coupled to another VCO thereof through a bidirectional coupling circuit.

12. The beam-steering system of claim 8, wherein the coupled VCO array is one of: a one-dimensional, a two-dimensional and a three-dimensional VCO array.

13. The beam-steering system of claim 8, wherein the secondary automatic servo loop is configured to limit the automatic fine pointing to operation over a limited pointing angle.

14. The beam-steering system of claim 8, further comprising a combiner circuit to combine outputs of the plurality of mixers as part of beamforming with the retro-directive antenna array.

15. A wireless communication system comprising:
a remote transmitter;
a jammer circuit; and
a beam-steering system comprising:
a retro-directive antenna array comprising a plurality of antenna elements, a receive beam of the retro-directive antenna array being attracted to the jammer circuit instead of the remote transmitter;
electronic circuitry associated with the retro-directive antenna array implemented with a capability to ignore the jammer circuit, and, in accordance therewith, move pointing of the receive beam away from the jammer circuit toward the remote transmitter, the electronic circuitry comprising a plurality of mixers, each of which is configured to mix a LO signal generated from a VCO of a coupled VCO array comprising a plurality of VCOs with a signal received at an antenna element; and
a secondary automatic servo loop implemented in the electronic circuitry associated with the retro-directive antenna array for automatic fine pointing of the receive beam toward the remote transmitter following the moving of the pointing of the receive beam toward the remote transmitter such that the receive beam exactly points to, and tracks, the remote transmitter.

16. The wireless communication system of claim 15, wherein the electronic circuitry associated with the retro-directive antenna array of the beam-steering system is configured to regard another remote transmitter as the jammer circuit during the moving of the pointing of the receive beam.

17. The wireless communication system of claim 15, wherein two or more VCOs of the coupled VCO array of the beam-steering system are configured to be injection locked to each other.

18. The wireless communication system of claim 15, wherein a VCO of the coupled VCO array of the beam-steering system is configured to be coupled to another VCO thereof through a bidirectional coupling circuit.

19. The wireless communication system of claim 15, wherein the secondary automatic servo loop of the beam-steering system is configured to limit the automatic fine pointing to operation over a limited pointing angle.

20. The wireless communication system of claim 15, wherein the beam-steering circuit further comprises a combiner circuit to combine outputs of the plurality of mixers as part of beamforming with the retro-directive antenna array.