A Multiport Impedance-Matching Feed Network for Directional Antennas

The proposed multiport impedance-matching feed network simultaneously optimizes the operating bandwidth and gain of a two-element superdirective antenna array. Maximum directivity of an
N
-element isotropic radiator approaches
N
²
as the element spacing approaches zero. Additionally, the operating bandwidth of superdirective antenna arrays is narrowband. Utilizing a multiport impedance-matching network will increase the operating bandwidth. Special consideration is required in designing the circuit so that the losses introduced by the matching network do not significantly degrade the absolute gain of the antenna array.