Multifunctional microstrip antennas

Claim 1

A multifunctional microstrip antenna system capable of simultaneously transmitting an outgoing circularly polarized wave and receiving an incoming circularly polarized wave when said incoming circularly polarized wave has an opposite sense of polarization with respect to said outgoing circularly polarized wave, said multifunctional microstrip antenna system comprising: a signal source which generates said outgoing circularly polarized wave; a microstrip patch antenna element which transmits said outgoing circularly polarized wave while simultaneously receiving said incoming circularly polarized wave wherein said microstrip patch antenna element comprises a truncated rectangular patch element which has at least one set of opposing corners removed, said truncated rectangular patch element having an input port which receives said outgoing circularly polarized wave thereby, said truncated rectangular patch element having an output port which outputs simultaneously said outgoing circularly polarized wave as well as said incoming circularly polarized wave; an attenuating means which is electrically connected to said signal source and said microstrip patch antenna element to conduct said outgoing circularly polarized wave from said signal source to said microstrip patch antenna element while providing an attenuation to said outgoing circularly polarized wave; a phase shifter which is electrically connected with said signal source and produces a phase-shifted outgoing circularly polarized wave which when combined with said outgoing circularly polarized wave acts to null it, wherein said phase shifter comprises a fixed phase shifter which provides a fixed phase shift to said outgoing circularly polarized wave to produce said phase-shifted outgoing circularly polarized wave; a directional coupler which is electrically connected with said phase shifter and said microstrip patch antenna element, said directional coupler thereby receiving said outgoing circularly polarized wave which is nulled with said phase-shifted outgoing circularly polarized wave as well as receiving conducting and outputting said incoming circularly polarized wave; and a receiver which is electrically connected to and receives said incoming circularly polarized wave from said directional coupler.