Proximity detection using adaptive mutual coupling cancellation

An apparatus comprising:

• at least two antennas, the at least two antennas including a first antenna and a second antenna, the first antenna and at least the second antenna mutually coupled electromagnetically;
• a wireless transceiver connected to the at least two antennas, the wireless transceiver configured to:
• transmit a radar transmit signal via the first antenna;
• receive multiple versions of a radar receive signal via multiple feed ports including at least one feed port of the second antenna, the radar receive signal comprising a reflected component corresponding to a reflection of the radar transmit signal via an object and a mutual coupling component corresponding to a transmission of the radar transmit signal via the first antenna;
• and
• adjust a transmission parameter based on a decoupled signal, the transmission parameter varying based on a range to the object;
• and
• a mutual coupling cancellation circuit connected to the multiple feed ports, the mutual coupling cancellation circuit configured to generate the decoupled signal based on the multiple versions of the radar receive signal such that the mutual coupling component is suppressed.

A method for proximity detection using adaptive mutual coupling cancellation, the method comprising:

• transmitting a radar transmit signal via a first antenna;
• receiving multiple versions of a radar receive signal via multiple feed ports including at least one feed port of a second antenna, the first antenna and the second antenna mutually coupled electromagnetically, the radar receive signal comprising a reflected component corresponding to a reflection of the radar transmit signal via an object and a mutual coupling component corresponding to a transmission of the radar transmit signal via the first antenna;
• generating a decoupled signal by processing the multiple versions of the radar receive signal such that the mutual coupling component is attenuated;
• and
• adjusting a transmission parameter based on the decoupled signal, the transmission parameter varying according to a range to the object.

An apparatus comprising:

• at least two antennas, the at least two antennas including:
• a first antenna configured to generate radiation;
• and
• a second antenna including multiple feed ports, the first antenna and the second antenna mutually coupled electromagnetically, the second antenna configured to generate multiple versions of a radio-frequency signal respectively via the multiple feed ports, the multiple versions of the radio-frequency signal including interference indicative of the radiation generated by the first antenna;
• and
• a mutual coupling cancellation module connected to the multiple feed ports, the mutual coupling cancellation module including:
• a zero-forcing combiner module configured to combine interference null-space projections of the multiple versions of the radio-frequency signal to attenuate the interference;
• and
• a reciprocal cancellation module configured to:
• scale a version of the multiple versions of the radio-frequency signal to produce a scaled signal;
• and
• subtract the scaled signal from another version of the multiple versions of the radio-frequency signal to attenuate the interference.