Dual-frequency filtenna using defected ground structure for VSAT applications

This paper presents the design of a dual-frequency filtenna using a defected ground structure (DGS). A shared aperture coupled microstrip antenna operating at 20/30 GHz (Ka band) is integrated with a coupled-line bandpass filter to increase the isolation between the transmit and receive channels. It is shown that the presence of slots in the ground plane can significantly increase the coupling between the coupled lines. The proposed technique allows for the design of tightly coupled lines without the necessity of using very narrow gaps. The integrated module can be made small enough to fit within an array unit cell for satellite communication applications.