Active reflector with oscillation inhibition

An active reflector comprising:

• an antenna;
• a bidirectional signal path coupled to the antenna;
• a directional coupler, coupled to the bidirectional signal path, a unidirectional receive signal path and a unidirectional transmit signal path, configured to convey a receive signal from the antenna to the unidirectional receive signal path and to convey a transmit signal from the unidirectional transmit signal path to the antenna;
• the unidirectional receive signal path configured to convey the receive signal;
• the unidirectional transmit signal path configured to convey the transmit signal;
• an active reflector circuit, coupled to the unidirectional receive signal path and the unidirectional transmit signal path, configured to generate the transmit signal by amplifying the receive signal and applying a phase shift in a range of phase shifts;
• and
• a calibration circuit, coupled to the active reflector circuit, configured to select the phase shift based at least in part on one or more measurements at different phase shifts in the range of phase shifts, wherein the calibration circuit is configured to sweep the phase shift over the range of phase shifts, and
• wherein the phase shift is selected to inhibit or reduce oscillation of the transmit signal associated with interference with the receive signal.

A vehicle, comprising:

• an active reflector, wherein the active reflector comprises:
• an antenna;
• a bidirectional signal path coupled to the antenna;
• a directional coupler, coupled to the bidirectional signal path, a unidirectional receive signal path and a unidirectional transmit signal path, configured to convey a receive signal from the antenna to the unidirectional receive signal path and to convey a transmit signal from the unidirectional transmit signal path to the antenna;
• the unidirectional receive signal path configured to convey the receive signal;
• the unidirectional transmit signal path configured to convey the transmit signal;
• an active reflector circuit, coupled to the unidirectional receive signal path and the unidirectional transmit signal path, configured to generate the transmit signal by amplifying the receive signal and applying a phase shift in a range of phase shifts;
• and
• a calibration circuit, coupled to the active reflector circuit, configured to select the phase shift based at least in part on one or more measurements at different phase shifts in the range of phase shifts, wherein the calibration circuit is configured to sweep the phase shift over the range of phase shifts, and
• wherein the phase shift is selected to inhibit or reduce oscillation of the transmit signal associated with interference with the receive signal.

A method for applying a phase shift, comprising:

• by an active reflector:
• receive, via a bidirectional signal path, a receive signal from an antenna;
• conveying, via a directional coupler and a unidirectional receive signal path, the receive signal to an active reflector circuit;
• generating, using the active reflector circuit, a transmit signal by amplifying the receive signal and applying the phase shift in a range of phase shifts;
• selecting, using a calibration circuit, the phase shift based at least in part on one or more measurements at different phase shifts in the range of phase shifts, wherein the selecting comprises sweeping the phase shift over the range of phase shifts, and wherein the phase shift is selected to inhibit or reduce oscillation of the transmit signal associated with interference with the receive signal;
• conveying, via a unidirectional transmit signal path, the directional coupler, the transmit signal to the bidirectional signal path;
• and
• providing, via the bidirectional signal path, the receive signal to the antenna.