Feasible load modulation technique using multiple antenna systems

In the passive multiple-input multiple-output transmission scheme, load modulation is applied to the multi-antenna, and a number of signals can be transmitted in parallel. The tag is defined as the multi-antenna that has load impedance, and it can control the reflective wave by switching its load impedance independently. The termination impedance pattern of the tag antennas is determined such that its reflection coefficients are to be distant from each other in a complex number plane. This technique can achieve multi-level modulation and high-speed data transmission without using the transmitter at the tag antenna.