Antenna array calibration systems and methods

Abstract

Aspects of this disclosure relate to an array calibration system and method using probes disposed between antenna elements. In certain embodiments, the calibration is performed by measuring near-field relative phase and amplitude measurements of the antenna elements and using such relative measurements to adjust the amplitude and phase of the transceivers connected to the antenna elements. In some embodiments, each antenna element within a set of antenna elements transmits a signal that is received by a single probe, and the received signals are assessed to determine relative phase or amplitude measurements. In some embodiments, a single probe transmits a signal that is received by each antenna element within a set of antenna elements, and the received signals are assessed to determine relative phase and amplitude measurements.

What is claimed is: 
     
         1 . An electronically-implemented method of an antenna array calibration comprising:
 determining a first near-field amplitude relationship for a first calibration group using a first probe of the antenna array, wherein the first calibration group comprises at least a first antenna element of an antenna array and a second antenna element of the antenna array, and the first probe is disposed symmetrically between the first antenna element and the second antenna element;   determining a first near-field phase relationship between at least the first antenna element and the second antenna element using the first probe; and   storing the first near-field amplitude relationship and the first near-field phase relationship as calibration data for the antenna array.   
     
     
         2 . The method of  claim 1  further comprising:
 determining a second near-field amplitude relationship for a second calibration group using a second probe of the antenna array, wherein the second calibration group comprises at least the second antenna element and a third antenna element of the antenna array, and the second probe is disposed symmetrically between the second antenna element and the third antenna element; 
 determining a second near-field phase relationship between at least the second antenna element and the third antenna element using the second probe; and 
 storing the second near-field amplitude relationship and the second near-field phase relationship as calibration data for the antenna array. 
 
     
     
         3 . The method of  claim 1 , wherein determining a first near-field amplitude relationship further comprises determining an amplitude relationship among the first antenna element, the second antenna element, a third antenna element of the antenna array, and a fourth antenna element of the antenna array using the first probe, wherein the first probe is disposed symmetrically between the first antenna element, the second antenna element, the third antenna element, and the fourth antenna element; and
 wherein determining a first near-field phase relationship further comprises determining a phase relationship among the first antenna element, the second antenna element, the third antenna element, and the fourth antenna element using the first probe.   
     
     
         4 . The method of  claim 1 , further comprising deactivating antenna elements that are not included in a particular calibration group during calibration of that particular calibration group. 
     
     
         5 . The method of  claim 1 , wherein determining a first near-field amplitude relationship further comprises:
 transmitting a radio frequency signal from a transmitter of the first antenna element monitoring signal levels received at the first probe with all other transmitters of the antenna array turned off; and   transmitting a radio frequency signal from a transmitter of the second antenna element monitoring signal levels received at the first probe with all other transmitters of the antenna array turned off.   
     
     
         6 . The method of  claim 5 , wherein determining a first near-field phase relationship further comprises:
 transmitting signals of the same amplitude from the transmitters of the first antenna element and the second antenna element; and   phase shifting the signals relative to each other to identify in phase configurations.   
     
     
         7 . The method of  claim 6 , wherein phase shifting is performed using a phased shifter. 
     
     
         8 . The method of  claim 6 , wherein determining a first near-field phase relationship further comprises:
 phase shifting the signals relative to each other to identify  180  degrees out of phase configurations.   
     
     
         9 . The method of  claim 5 , wherein the signal levels comprise amplitude measurement. 
     
     
         10 . The method of  claim 5 , wherein the signal levels comprise phase measurement. 
     
     
         11 . The method of  claim 1 , wherein determining a first near-field amplitude relationship further comprises transmitting a radio frequency signal from the probe and monitoring signal levels received at the first and second antenna elements. 
     
     
         12 . The method of  claim 11 , wherein determining a first near-field phase relationship further comprises:
 receiving signals that are transmitted from the probe, wherein the transmitted signals are of the same amplitude; and   phase shifting the received signals relative to each other to identify in phase configurations at the first and second antenna elements.   
     
     
         13 . An apparatus with built-in calibration components comprising:
 a plurality of antenna elements of an antenna array;   a plurality of probes of the antenna array, wherein the probes are disposed symmetrically between groups of antenna elements of the plurality of antenna elements, wherein the groups number at least two antenna elements each, wherein the probes can receive radio-frequency (RF) signals and each of the antenna elements can transmit RF signals for built-in near-field calibration of the antenna array; and   a hardware processor of the antenna array configured to calibrate the antenna array by observations of near-field radiation obtained by using the plurality of probes.   
     
     
         14 . The apparatus of  claim 13  wherein the groups number at least four antenna elements each. 
     
     
         15 . The apparatus of  claim 13 , wherein the hardware processor is further configured to adjust a variable gain amplifier of at least one antenna element to calibrate the antenna array. 
     
     
         16 . The apparatus of  claim 13 , wherein the hardware processor is further configured to adjust a phase shifter of at least one antenna element to calibrate the antenna array. 
     
     
         17 . An electronically-implemented method of calibrating an antenna array, the method comprising:
 observing radiation patterns in near field measurements at least between groups of antenna elements via probes symmetrically disposed between the groups of antenna elements of the antenna array to obtain relative amplitude and phase relationships among the antenna elements of the array;   generating amplitude and phase adjustments based at least in part on the obtained relative amplitude and phase relationships and on a desired antenna pattern; and   applying the generated amplitude and phase adjustments to obtain the desired antenna pattern.   
     
     
         18 . The method of  claim 17 , further comprising repeating observing radiation patterns across a plurality of channels comprising different frequencies. 
     
     
         19 . The method of  claims 17 , wherein the antenna elements and probes of the antenna array are disposed in a single or multiple array panels.