Cooperative Interference Control in Neighboring Passive Scattering Antennas

Passive backscattering links in scattering sensor arrays suffer from mutual coupling among closely spaced neighbor antennas. This effect results in an unmatched circuitry at input ports of antennas causing poor power harvesting, weak backscattering, overall low read rates. In this paper, a model for mutual coupling in a N by N scattering antenna arrays is discussed. We show by simulations and measurements that in a two scatterer system (one target and one neighbor antennas) the mutual coupling effect from the neighbor to the target varies depending on its load and also its location with respect to the target and the incident wave. We show that by load switching at neighbor antenna mutual coupling effect can be controlled to produce constructive interference at target antenna. Next, cooperative interference control by load switching is examined in a scattering antenna arrays. Simulation results show that by load switching at neighboring scatterers in a 3 by 3 scattering array the signal of a target antenna-which is proportional to its induced current-in the back row can be improved by ~21 dB.