Transmitting or receiving circularly polarized signals by linearly polarized antennas

A method, comprising:

• generating, by processing circuitry of an apparatus, a transmitted baseband signal vector;
• generating, by power amplifiers (PAs) of the apparatus, transmitted radio frequency (RF) signals based on the transmitted baseband signal vector;
• receiving, by receiving circuitry of the apparatus, the transmitted RF signals to obtain a received baseband signal vector, wherein the received baseband signal vector includes a first sub-vector and a second sub-vector, the first sub-vector being generated based on a first transmitted RF signal of the transmitted RF signals output from a first PA of the PAs coupled to a horizontally polarized antenna, and the second sub-vector being generated based on a second transmitted RF signal of the transmitted RF signals output from a second PA of the PAs coupled to a vertically polarized antenna;
• calibrating, by a controller of the apparatus, the PAs and local oscillator (LO) signals of frequency converters of the apparatus based on the received baseband signal vector;
• and
• transmitting, by the horizontally polarized antenna and the vertically polarized antenna of the apparatus, a circularly polarized signal based on the calibrated PAs and the calibrated LO signals.