Design of a planar broadband capacitive-loaded antenna with bow-tie section

A novel planar broadband antenna with series capacitive loading is presented in this paper. The proposed antenna consists of 12 metal patches. The desired capacitive loading is achieved by fixing gaps between the conductive patches. The widths of these gaps are increasing from the feed end along the monopole. The loaded capacitance leads to good broadband characteristics of the proposed antenna. Stubs are added on both sides of the patches and a bottom bow-tie section is introduced to further increase the bandwidth. An enhanced impedance bandwidth of 5.6:1 ranging from 530 MHz to 3000 MHz with S11 <; -6 dB (SWR <; 3) is achieved. The proposed antenna gives monopole-like pattern and a nearly omnidirectional pattern in the azimuth plane. The proposed antenna can be used for UHF vehicular or ship-board communication systems.