Virtual antenna technology (VAT) and applications
View Patent ↗Within an antenna array 120, the magnitude and phase of a relationship resulting from propagation delay between a sample taken at a first antenna 1 to a sample taken at a second antenna 2 at a different time is employed to derive a data value for a virtual antenna 3. Sub-patch antennas 203 perturbed in elevation are employed to expand the elevation range of acceptable gain. Multiple arrays each providing a separate radio frequency output are employed with digital beamform steering to a single point, together with low noise amplification at the feed point, to achieve sufficient gain with an acceptable total array size. A modular implementation with fiber transport is preferably used.
1. An antenna array system comprising:
a plurality of spaced antenna elements; and
a controller coupled to the antenna elements, the controller determining a magnitude and phase relationship between a first signal sample taken at a first antenna element at a first time and a second signal sample taken at a second antenna element at a second time, the controller employing the magnitude and phase relationship to compute a projected signal sample for a virtual antenna element based on a third signal sample taken at the first antenna element at the second time.
2. The antenna array system according to claim 1 , wherein the projected signal sample is employed as a signal sample taken at the virtual antenna element at the first time.
3. The antenna array system according to claim 1 , wherein the plurality of antenna elements are linearly aligned, the antenna array system further comprising:
a plurality of mixers each mixing a signal received at one of the antenna elements with a local oscillator frequency signal;
a plurality of analog-to-digital converters each receiving a mixed output from one of the mixers and converting the mixed output to a digital signal, wherein the controller receive the digital signals and computes the projected signal sample based on the digital signals; and
a digital signal processor receiving the digital signals from each of the analog-to-digital converters together with the projected signal sample from the controller.
4. The antenna array system according to claim 1 , wherein the antenna array system has a beamformed array gain and half power bandwidth proportional to a number of antenna elements greater than a number of the plurality of antenna elements.
5. The antenna array system according to claim 1 , wherein the controller determines multiple magnitude and phase relationships between signal samples taken at different antenna elements at different times and computes a plurality of virtual signal samples.
6. The antenna array system according to claim 5 , wherein the antenna array system has a beamformed array gain and half power bandwidth proportional to M+P·(M−1), where M is a number of the plurality of antenna elements and P is a number of the virtual signal samples.
7. The antenna array system according to claim 1 , wherein a virtual sensor is achieved by blind mapping, without movement of antenna array elements.
8. A system including the antenna array system according to claim 1 , the system further comprising:
a plurality of arrays of patch antennas arranged in rows and columns, one of the plurality of arrays including the spaced antenna elements, wherein signals from each patch antenna within a given array are summed in phase,
wherein the controller further comprises a multi-element digital beamformer phasing signals from each of the plurality of arrays to a single point.
9. The system according to claim 8 , wherein each of the arrays is perturbed in elevation angle with respect to the remaining arrays.
10. The system according to claim 8 , further comprising:
low noise amplifiers connected to feed points for each of the plurality of arrays; and
a downconverter operating on outputs of the low noise amplifiers.
11. The system according to claim 10 , wherein the antenna elements, low noise elements, and downconverter are implemented within one module coupled by a fiber cable to a digital signal processor.
12. A method of controlling an antenna array system comprising:
determining a magnitude and phase relationship between a first signal sample taken at a first antenna element within a plurality of spaced antenna elements at a first time and a second signal sample taken at a second antenna element within the plurality of spaced antenna elements at a second time;
employing the magnitude and phase relationship to compute a projected signal sample for a virtual antenna element based on a third signal sample taken at the first antenna element at the second time.
13. The method according to claim 12 , further comprising:
employing the projected signal sample as a signal sample taken at the virtual antenna element at the first time.
14. The method according to claim 12 , wherein the plurality of antenna elements are linearly aligned, the method further comprising:
mixing each signal received at one of the antenna elements with a local oscillator frequency signal;
receiving mixed outputs from the mixing and converting each of the mixed outputs from an analog signal to a digital signal, wherein the projected signal sample is computed based on the digital signals; and
digitally processing the digital signals together with the projected signal sample.
15. The method according to claim 12 , wherein the antenna array system has a beamformed array gain and half power bandwidth proportional to a number of antenna elements greater than a number of the plurality of antenna elements.
16. The method according to claim 12 , further comprising:
determining multiple magnitude and phase relationships between signal samples taken at different antenna elements at different times; and
computing a plurality of virtual signal samples.
17. The method according to claim 16 , wherein the antenna array system has a beamformed array gain and half power bandwidth proportional to M+P·(M−1), where M is a number of the plurality of antenna elements and P is a number of the virtual signal samples.
18. The method according to claim 12 , wherein a virtual sensor is achieved by blind mapping, without movement of antenna array elements.
19. An antenna system comprising:
a plurality of M spaced antenna elements each received signal;
a plurality of M mixers, each mixer mixing a received signal from one of the antenna elements with a local oscillator frequency;
a plurality of M analog-to-digital converters, each analong-to-digital converter converting an output of one of the mixers to a digital signal;
a virtual antenna controller receiving the digital signals, the virtual antenna controller sampling all of the digital signals at each of a plurality of times,
determining a magnitude and phase relationship between
a first of the digital signals corresponding to the received signal at a first of the M antenna elements at a first time t 1 and
a second of the digital signals corresponding to the received signal at a second of the M antenna elements at a second time t 2 , and
employing the magnitude and phase relationship to compute a projected digital signal for a virtual antenna element based on a third of the digital signals corresponding to the received signal at the first antenna element at the second time t 2 ; and
a digital signal processor operating on, collectively, the second and third digital signals and the projected digital signal.
20. The antenna system according to claim 19 , wherein the antenna system operates with an array gain and half power bandwidth proportional to an array of M+1 antenna elements.
21. A controller for use with a plurality of spaced antenna elements comprising:
a controller that, when operable and coupled to the antenna elements,
receives at least a first signal sample taken at a first antenna element at a first time,
a second signal sample taken at a second antenna element at a second time, and a third signal sample taken at the first antenna element at the second time,
determines a magnitude and phase relationship between the first signal sample and the second signal sample, and
employs the magnitude and phase relationship to compute a projected signal sample for a virtual antenna element based on the third signal sample.
22. The controller according to claim 21 , wherein the projected signal sample is employed as a signal sample taken at the virtual antenna element at the first time.
23. The controller according to claim 21 , wherein the controller determines multiple magnitude and phase relationships between signal samples taken at different antenna elements at different times and computes a plurality of virtual signal samples.
24. A system including the controller according to claim 21 , the system further comprising:
a plurality of arrays of patch antennas arranged in rows and columns, one of the plurality of arrays including the spaced antenna elements, wherein signals from each patch antenna within a given array are summed in phase,
wherein the controller further comprises a multi-element digital beamformer phasing signals from each of the plurality of arrays to a single point.