Design of compact low-profile planar filtering antenna with enhanced suppression level

A compact low-profile planar filtering antenna with an enhanced suppression level is presented in this paper. The presented antenna has a simple structure, consisting of an E-shaped driving patch, a shorted parasitic patch, and a defected ground structure (DGS). The E-shaped driving patch serves as an effective radiator and facilitates the filtering response. The shorted parasitic patch is horizontally arranged and coupled with the driving patch through the radiating edge. And a radiation null and an extra in-band resonance can be generated, which would simultaneously broaden the impedance bandwidth and improve the suppression level. In addition, a DGS on the metalized ground plane is etched to introduce another radiation null, and the out-of-band suppression level would be significantly enhanced. The filtering antenna with a center frequency of 3 GHz was constructed and tested to verify its performance. The measured values, which indicate a bandwidth of 10% (2.85-3.15 GHz) and a peak realized gain of 5.2 dBi, are in agreement with the simulated values. The presented filtering antenna features a low profile of 0.016 & lambda;0, a compact antenna size of 0.16 & lambda;20, as well as an improved suppression level of more than 22 dB.