Electrically Small Complementary Pair (ESCP) with Inter-Element Coupling

Electrically small (reduced size) antennas are inherently narrowband, 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 improvmement in gain-bandwidth product as compared to conventional matching techniques for electrically small antennas. In addition, the complementarization circuit in conjunction with the hybrid feed can reduce the effects of mutual impedances in steerable-beam arrays. Applications include small individual antennas and scatterers as well as linear, planar, or circular arrays in a variety of fixed-station or vehicular uses. Various types of decoys and ECM systems for aircraft and missiles are examples of potential applications of electrically small antennas and scatterers. Large, hardened, ground-based phased arrays and wideband communication base station antennas are typical phased-array applications in fixed stations. Vehicular applications encompass wideband direction finders, aircraft conformal antennas for various functions, and high-performance spacecraft antennas for communications and radar systems. (Author)