Electrically small complementary pair (ESCP) with interelement coupling

Electrically small (reduced size) antennas are inherently narrow-band or inefficient, or both. A summary is presented of prior work on complementary pair antennas and the use of the coupling between the two elements to optimize the impedance match and efficiency of such structures. The design of electrically small complementary pairs is described, and preliminary measurement results are shown for monopoles. These measurements indicate a substantial improvement in gain-bandwidth product as compared to conventional matching techniques for electrically small antennas. The power delivered to the external region is analyzed for both an individual monopole, and a pair of monopoles, by establishing the scattering matrices for both cases. The potential gain is calculated for the pair over the individual monopole, and it is shown that the pair can deliver up to twice the power to the exterior region if the mutual impedance term is optimized. In addition, the complementarization circuit in conjunction with the hybrid feed can reduce the effects of mutual impedances in steerable-beam arrays. Various special cases are discussed, varying from full complementarity to zero complementarity, and general conclusions are presented on the optimization of gain-bandwidth product. Applications include small individual antennas and scatterers as well as linear, planar, or circular arrays in a variety of fixed-station or vehicular uses.