Zeroth Order Resonance Loop Antenna

A new type of low-profile omnidirectional antenna is proposed in this paper. The proposed antenna has the conceptual configuration of the horizontal magnetic loop current on perfect electric conductor plane, which has been realized by the zeroth-order resonator (ZOR) antenna using mushroom structure. 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. In particular, mushroom ZOR antenna generates a uniform vertical electric field against ground plane, so that it omnidirectionally radiates in a horizontal plane. Operation frequency, absolute gain, and gain variations for omnidirectional radiation of the designed prototype are 7.9 GHz, 2.6dBi, less than 1.5 dBi, respectively