RCS of broadband gap-coupled microstrip antennas

The effect parasitic loading has on microstrip patch RCS (radar cross section) is determined, and methods for RCS reduction are investigated. The RCS of a microstrip dipole parasitically coupled to another dipole is investigated initially. The broadside RCS of a 5.0 cm /spl times/ .0002 cm dipole with and without impedance loading is shown along with the effect on RCS that coupling to another such dipole (center-to-center spacing is 0.1 cm) produces. It is seen that impedance loading reduces the RCS of the isolated dipole by approximately 20 dB. Tight coupling to an unloaded element, which would be encountered when using parasitic coupling to increase impedance bandwidth, increases the RCS of the two-element system. Impedance loading either element of the two-element system reduces the RCS below that of an unloaded isolated element. Loading both elements further reduces the RCS, which still remains above the level of the loaded, isolated dipole.<>