Polarimetric Demodulator Based on a Seven-Port Network

This paper presents the theoretical basis and the experimental validation of a seven-port microwave demodulator capable of measuring the polarization and the complex envelope of the incoming signal. The proposed architecture is a variant of the six-port demodulator in which four power detectors are used to generate the baseband in-phase and quadrature-phase data. This six-port technique provides simpler circuits with lower cost and lower consumption with respect to the conventional quadrature demodulator. The additional port (seventh port) in our novel design provides additional information to recover the polarization of the received signal. In the paper, the analytical expressions of the polarization and the complex envelope of the incoming signal are derived as a function of the four power measurements. A prototype of the demodulator is designed and implemented for a central frequency of 1575 MHz. Measurements validate the theory by showing good agreement between the theoretical and experimental results.