A cavity-backed slot ESPAR E-plane array

A three-element cavity-backed slot ESPAR E-plane array is proposed in this paper. As with conventional ESPAR antennas, the parasitic cavities are fed by mutually coupling to the center cavity and each parasitic cavity is terminated with a tunable capacitor that provides the necessary phase shift for the desired beam scanning performance. Due to the difficulty of achieving E-plane coupling while simultaneously controlling the coupling level and phase, there have been few reported E-plane ESPAR antennas in the literature. In this paper, it is shown that these challenges can be overcome by exploiting the cavity geometry to achieve the desired coupling values; the required phase shift is achieved by changing the load impedance of the parasitic cavities. In full-wave simulations, it is observed that the proposed ESPAR E-plane array is able to steer the beam from -30 to 30 degrees, which is comparable to the beam-steering range of ESPAR antennas operating in the H-plane.