Design of impedance loading board supporting load-modulated beamspace MIMO single RF system

This paper presents a design of an impedance loading RF circuit board and its performance evaluation, as well as, air transmission results of BPSK modulated signal. The single RF load-modulated beamspace MIMO system controls the signal by changing the impedance loaded on each antenna, and all antennas and impedance loading boards share a single power amplifier, and thus it obviates the need for using multiple number of RF components (e.g. DAC, power amp, and mixer) in MIMO system. This leads to huge benefits for the system that requires large number of antennas, such as a massive MIMO system. The impedance loading board is examined with Tx-Rx distance of 3 m, transmitting 40 Mbps BPSK signal, while consuming 15 mW.