An UHF Tree-Like Biconical Antenna With Both Conical and Horizontal Omnidirectional Radiations

A tree-like biconical antenna with both conical and horizontal omnidirectional radiations is designed for UHF vehicle application. The biconical antenna is realized by several radial wires instead of an entity structure, and the lower radial wires are inverted to form a conical reflector for conical omnidirectional radiation while the intrinsic horizontal omnidrectional radiation of biconical antenna is maintained. Moreover, a cone load is added to improve the impedance bandwidth. Measurements show that the antenna achieves both conical and horizontal omnidirectional radiations with the gains of 5-9 and 1.3-2.8 dBi over an impedance bandwidth of 41.1% from 560 to 850 MHz.