Simultaneous transmit and receive through active cancellation
A simultaneous transmit and receive (STAR) system comprises a plurality of radiating elements and a plurality of antenna transmit/receive (T/R) elements. The plurality of antenna T/R elements are each in operable communication with a respective radiating element. Each T/R element comprises a transmit channel, a receive channel, a switch, and a directional coupler. The directional coupler comprises an RF input in operable communication with an antenna array receiving signals, an RF output coupling the received signals to an input of the receive channel, and a coupled input operably coupled to the switch. If the switch is set to a predetermined state, the respective transmit channel couples an active cancellation signal to the coupled input of the directional coupler to cancel at least some coupling effects arising on an input to the receive channel, arising from operation of at least some of the T/R elements in the array.
1 . A simultaneous transmit and receive (STAR) system, comprising:
a plurality of radiating elements configured as part of an antenna array, the antenna array configured for transmitting signals and for receiving signals; and
a plurality of antenna transmit/receive (T/R) elements, each respective T/R element being in operable communication with a respective radiating element, each respective T/R element comprising a transmit channel, a receive channel, a switch, and a directional coupler, wherein, for each respective T/R element:
the directional coupler comprises a radiofrequency (RF) input in operable communication with the antenna array to receive a signal received by the antenna array, an RF output configured to couple the received signal to an input of the receive channel, and a coupled input in operable communication with the switch; and
when the switch is set to a first predetermined state, the transmit channel is configured to couple an active cancellation signal to the coupled input of the directional coupler, the active cancellation signal configured to cancel at least some coupling effects that arise on an input to the receive channel, the coupling effects arising from operation of at least a portion of the plurality of T/R elements.
2 . The STAR system of claim 1 , wherein, for each respective T/R element, the active cancellation signal is configured to enable the input to the receive channel to be as close a match as possible to the signal received by the antenna array.
3 . The STAR system of claim 1 , wherein:
a transmit channel input of at least a first T/R element of the plurality of T/R elements is configured to receive the respective active cancellation signal at substantially a same time that at least a second T/R element of the plurality of T/R elements is configured to receive a transmit signal to be provided to the respective radiating element of the second T/R element; and
the respective active cancellation signal at the first T/R element is configured to cancel at least one coupling effect that appears at the first T/R element and that is caused by the second T/R element.
4 . The STAR system of claim 1 , wherein:
the antenna array further comprises transmit and receive channels; and
the active cancellation signal for each respective T/R element is based at least in part on a coupling matrix for the antenna array and on at least one characterization of at least one of the transmit channels and the receive channels of the antenna array.
5 . The STAR system of claim 1 , wherein:
the active cancellation signal for each respective T/R element is based at least in part on one or more parameters out of a set of parameters measured and determined during a calibration of the antenna array; and
the set of parameters comprises a maximum delay necessary to fully characterize signal coupling in the antenna array, a receive element number, a transmit element number, one or more characterized feedback paths, one or more characterized coupling matrix values, knowledge of an antenna array channel's characterization, knowledge of a commanded excitation for each antenna element at a given time sample, and one or more antenna array channel transmit output signals.
6 . The STAR system of claim 1 , wherein, for each respective T/R element, the first predetermined state comprises a feedback state configured to couple an output of the transmit channel to the coupled input of the directional coupler.
7 . The STAR system of claim 1 , wherein, for each respective T/R element, when the switch is set to a second predetermined state, an output of the transmit channel is coupled to the respective radiating element.
8 . The STAR system of claim 1 , wherein:
a first subset of T/R elements are configured to have their respective switches set to the first predetermined state; and
the first predetermined state comprises, for each of the first subset of T/R elements, a feedback state configured to couple an output of the transmit channel to the coupled input of the directional coupler.
9 . The STAR system of claim 8 , wherein a second subset of T/R elements are configured to have their respective switches set to a second predetermined state in which, for each of the second subset of T/R elements, an output of the transmit channel is coupled to the respective radiating element.
10 . The STAR system of claim 1 , wherein, for each respective T/R element:
the switch comprises an input in operable communication with an output of the transmit channel, a transmit pole in operable communication with the respective radiating element, and a feedback pole in operable communication with the coupled input of the directional coupler;
wherein the switch is set to the transmit pole, the output of the transmit channel is provided to the respective radiating element; and
wherein the switch is set to the feedback pole, the output of the transmit channel is provided to the coupled input of the directional coupler.
11 . A simultaneous transmit and receive (STAR) system, comprising:
a plurality of radiating elements configured as part of an antenna array, the antenna array configured for transmitting signals and for receiving signals; and
a plurality of antenna transmit/receive (T/R) elements, each respective T/R element being in operable communication with a respective radiating element, each respective T/R element comprising a first transmit channel, a second transmit channel independent of the first transmit channel, a receive channel, and a directional coupler, wherein, for each respective T/R element:
the first transmit channel has an input configured to receive a signal to be transmitted and an output configured to operably couple the signal to be transmitted to the respective radiating element;
the second transmit channel has an input configured to receive an active cancellation signal and an output configured to operably couple the active cancellation signal to the directional coupler;
the directional coupler comprises a radiofrequency (RF) input in operable communication with the antenna array to receive a signal received by the antenna array, an RF output configured to couple the received signal to an input of the receive channel, and a coupled input in operable communication with the output of the second transmit channel; and
the active cancellation signal is configured to cancel at least some coupling effects that arise on an input to the receive channel, the coupling effects arising from operation of at least a portion of the plurality of T/R elements.
12 . The STAR system of claim 11 , wherein, for each respective T/R element, the active cancellation signal is configured to enable the input to the receive channel to be as close a match as possible to the signal received by the antenna array.
13 . The STAR system of claim 11 , wherein, for each respective T/R element, the input of the second transmit channel is configured to receive the active cancellation signal at substantially a same time that the first transmit channel is configured to receive the signal to be transmitted.
14 . The STAR system of claim 11 , wherein:
the input of the second transmit channel of a first T/R element of the plurality of T/R elements is configured to receive the active cancellation signal at substantially a same time that the input of the first transmit channel of any respective T/R element of the plurality of T/R elements is configured to receive a transmit signal to be provided to the respective T/R element's respective radiating element; and
the active cancellation signal at the first T/R element is configured to cancel at least one coupling effect that appears at the first T/R element and that is caused by the respective T/R element.
15 . The STAR system of claim 11 , wherein:
the antenna array further comprises transmit channels and receive channels; and
the active cancellation signal for each respective T/R element is based at least in part on a coupling matrix for the antenna array and on at least one characterization of at least one of the transmit channels and the receive channels of the antenna array.
16 . The STAR system of claim 11 , wherein:
the active cancellation signal for each respective T/R element is based at least in part on one or more parameters out of a set of parameters measured and determined during a calibration of the antenna array; and
the set of parameters comprises a maximum delay necessary to fully characterize signal coupling in the antenna array, a receive element number, a transmit element number, one or more characterized feedback paths, one or more characterized coupling matrix values, knowledge of an antenna array channel's characterization, knowledge of a commanded excitation for each antenna element at a given time sample, and one or more antenna array channel transmit output signals.
17 . A method for simultaneous transmit and receive (STAR) operation, comprising:
operating a system comprising (i) a plurality of radiating elements configured as part of an antenna array, the antenna array configured for transmitting signals and for receiving signals, and (ii) a plurality of antenna transmit/receive (T/R) elements coupled to be in operable communication with the plurality of radiating elements, wherein:
each respective T/R element is in operable communication with a respective radiating element;
each respective T/R element comprises a first transmit channel, a receive channel, a switch, and a directional coupler; and
for each respective T/R element:
the directional coupler comprises a radiofrequency (RF) input in operable communication with the antenna array to receive signals received by the antenna array, an RF output configured to couple the received signals to an input of the receive channel, and a coupled input in operable communication with the switch; and
the switch comprises an input in operable communication with an output of the first transmit channel, a transmit pole in operable communication with the respective radiating element, and a feedback pole in operable communication with the coupled input of the directional coupler;
setting, for at least a first T/R element of the plurality of T/R elements, the switch of the first T/R element to the transmit pole to cause an output of the first transmit channel of the first T/R element to be provided to the respective radiating element for the first T/R element;
setting, for at least a second of the plurality of T/R elements, the switch of the second T/R element to the feedback pole to cause an output of the first transmit channel of the second T/R element to be provided to the coupled input of the directional coupler;
providing a transmit signal to an input of the first transmit channel of the first T/R element, wherein the first T/R element provides the transmit signal to its respective radiating element to be radiated into a target area;
receiving, at the antenna array, a received signal that is provided to an input of the receive channel of the second T/R element; and
providing an active cancellation signal to an input of the first transmit channel of the second T/R element, wherein the directional coupler of the second T/R element is configured to provide the active cancellation signal to the input of the receive channel of the second T/R element, wherein the active cancellation signal is configured to cancel at least some coupling effects that arise on the input to the receive channel of the second T/R element, the coupling effects arising from providing the transmit signal to the first T/R element, and wherein the active cancellation signal is configured to enable the input to the receive channel to be as close a match as possible to the received signal.
18 . The method of claim 17 , wherein the active cancellation signal is provided as an input to the first transmit channel of the second T/R element at substantially a same time that the transmit signal is provided as an input to the first transmit channel of the first T/R element.
19 . The method of claim 17 , wherein:
the antenna array further comprises transmit channels and receive channels; and
the active cancellation signal is generated based at least in part on one or more of:
a coupling matrix for the antenna array;
at least one characterization of at least one of the transmit channels and the receive channels of the antenna array; and
one or more parameters out of a set of parameters measured and determined during a calibration of the antenna array, the set of parameters comprising a maximum delay necessary to fully characterize signal coupling in the antenna array, a receive element number, a transmit element number, one or more characterized feedback paths, one or more characterized coupling matrix values, knowledge of an antenna array channel's characterization, knowledge of a commanded excitation for each antenna element at a given time sample, and one or more antenna array channel transmit output signals.
20 . The method of claim 17 , wherein:
each respective T/R element further comprises a second transmit channel having an input configured to receive the active cancellation signal and an output configured to couple the active cancellation signal to the directional coupler; and
the method further comprises:
receiving, at the input of the second transmit channel of the first T/R element, the active cancellation signal, wherein the active cancellation signal is received at substantially a same time that the transmit signal is provided to the input of the first transmit channel of the first T/R element; and
configuring the active cancellation signal to cancel at least one coupling effect that appears at the first T/R element and that is caused by any other T/R element.