Wideband Omnidirectional Filtering Antenna with CSRR loading

A wideband omnidirectional filtering antenna with complementary split ring resonator (CSRR) loading is presented in this paper. The antenna consists of two circular patches and two circles of CSRRs. And there is a set of short vias between the driven circular patch and ground. Two circles of CSRRs are used to enhance the bandwidth of the antenna and provide radiation null at the lower band edge. A stacked circular patch can generate the upper edge radiation null. Under the above structures, the proposed antenna exhibits a good bandpass filtering response without additional filter circuit. The prototype has a measured impedance bandwidth of 36.4% (4.94 - 7.14GHz) with a profile of 0.029λ
₀
. The out-of-band suppression reaches to 15dB.