Dual frequency ZOR patch antenna with two stubs

In this paper, the mushroom structure as a transmission line has negative, zero, and positive propagation constant depending on its operation frequency since mushroom structure is artificial composite right-left handed transmission line. Zeroth-order resonance, of which frequency is independent of physical length, is naturally presented. Design of probe fed zeroth order resonance (ZOR) antenna with dual frequency operation is presented. The slot in the patch is placed at the center of the geometry and the grounded via to have the desired ZOR response. However, in this work we presented ZOR antenna which excites dual resonances at 5.70GHz and 8.52GHz respectively. The second resonance is obtained by placing two stubs and an outer ring. Also, it may be noted that we get nearly broader E-plane beamwidths (120 and 104 degrees) at both the resonance frequencies. From this structure we can get flat gain response at the operating frequencies.