Design of a Seven-Port Demodulator for Wireless Applications with Multiple Antennas

This paper presents a seven-port microwave demodulator capable of measuring the complex envelopes of three incoming signals received by different antennas. The proposed architecture is based on the six-port technique in which four power detectors are used to generate the baseband in-phase (I) and quadrature-phase (Q) data of the signal received by an antenna. In our design, a seven-port structure is used to connect three antennas, a local oscillator, and three power detectors. In order to obtain the baseband I and Q data by the power measurements, a signal processing approach based on the Hilbert transform is presented. Experimental results are used for validation of the theory. The prototype demodulator is designed and implemented for a central frequency of 1575.42 MHz (GPS L1 band) for validation of the proposed architecture.