Horizontally Polarized Omnidirectional Antenna Array Using Cascaded Cavities

A new structure of horizontally polarized (HP) antenna array is presented for azimuthal omnidirectional coverage. The proposed antenna array is engineered by breaking the fringing held symmetry along the typical parallel strip-lines, which is implemented by loading held-block structures alternatively and periodically. In physics, the blocking structures constrain the fringing helds inside, producing a series of rectangular open cavities operating at the TM_1n0 (n = 0.5) mode. Counterintuitively, these asymmetric open cavities are able to generate an omnidirectional radiation pattern in the E plane with horizontal polarization, similar to the linear magnetic current array. In order to verify the design strategy, a hve-unit center-fed cascaded cavity array is fabricated and tested. The measured bandwidth is 120 MHz (5.83-5.95 GHz) with reflection coefhcient lower than -10 dB. The HP omnidirectional pattern at 5.9 GHz provides a gain variation of 1.94 dB ranging from 6.7-8.64 dBi.