Method and system for propagation time measurement and calibration using mutual coupling in a radio frequency transmit/receive system

A method for measuring aspects of signal propagation times among various transmitting or receiving signal paths in a radio frequency transmit/receive system for calibrating said signal paths to a common time reference, comprising:

• generating a first and a second radio frequency reference signals;
• transmitting the first reference signal through a first transmit side comprising a first transmitting signal path comprising a first antenna radiating element, wherein the first transmitting signal path and the first antenna radiating element are also usable for transmitting an operational signal, and wherein the operation signal is different from the reference signal;
• transmitting the first reference signal through a local oscillator feed line to a mixer:
• propagating the transmitted first reference signal through a first mutual coupling field from said first antenna radiating element to an antenna receiving element;
• receiving, by the mixer, a first propagated reference signal through a receive side comprising a receiving signal path including the antenna receiving element, wherein the receiving signal path and the antenna receiving element are also usable for receiving the operational signal;
• mixing the first propagated reference signal with the first reference signal by the mixer;
• acquiring a first heterodyned signal from the mixer;
• analyzing a first frequency profile of the first propagated reference signal to determine a difference in arrival time of the first reference signal and the first propagated reference signal at the mixer;
• transmitting the second reference signal through a second transmit side comprising a second transmitting signal path comprising a second antenna radiating element, wherein the second transmitting signal path and the second antenna radiating element are also usable for transmitting the operational signal;
• transmitting the second reference signal through the local oscillator feed line to the mixer;
• propagating the transmitted second reference signal throuqh a second mutual coupling field from said second antenna radiating element to the antenna receiving element;
• receiving, by the mixer, a second propagated reference signal through said receive side;
• mixing the second propagated reference signal with the second reference signal by the mixer;
• acquiring a second heterodyned signal from the mixer;
• analyzing a second frequency profile of the second propagated reference signal to determine a difference in arrival time of the second reference signal and the second propagated reference signal at the mixer;
• and
• processing the difference in arrival time of the first reference signal and the first propagated reference signal and the difference in arrival time of the second reference signal and the second propagated reference signal to determine a relative propagation time difference between the first transmitting and the second transmitting signal paths.