Aperture coupling to increase the bandwidth of thin cavity antennas

The authors present a theoretical analysis of a stacked antenna system consisting of a driven resonator coupled to a second resonator via an aperture in a common wall. The antennas are thin, rectangular, cavity-backed slot resonators. These resonators consist of five conducting walls, leaving the sixth open to allow radiation. The final structure consists of two identical cavities, one stacked above the other, with the radiating edges on opposing sides. The lower resonator is driven by a probe and coupled to the second resonator through an aperture in a common wall. The cavity model theory developed by W.F. Richards, Y.T. Lo, and D.D. Harrison (IEEE Trans. Antennas Propagat., AP-21, no.1, p.38-46, Jan. 1981) was used to predict the input impedance of this stacked antenna. Preliminary results show good qualitative agreement between theoretical and measured data. The theoretical input impedance clearly shows the effect of coupling between the resonators. In addition, the impedance correctly predicts the effect of changing the dimensions of the coupling aperture.<>