A Wideband and Vertically Polarized Flush-Mounted Antenna With High Horizontal Gain Using Distributed Dielectric Loading

This letter presents a wideband, vertically-polarized, and omnidirectional antenna that is wholly flush-mounted in the metallic carrier with enhanced gain in the horizontal direction by using distributed dielectric loading. The wideband and low-profile properties of the monocone antenna are achieved through top hat and shorting pins loading. The affection mechanism of the dielectric loading is studied to mitigate the performance degradation of the flush-mounted antenna. Through optimizing the shape and position of the dielectrics, the propagation direction of the radiated electromagnetic (EM) wave is altered, which effectively regulates the radiation pattern of the antenna. Thus, the horizontal gain is improved remarkably and this feature is very important for omnidirectional communication systems. The proposed antenna is fabricated and measured to verify the design concept. The measured results show that the antenna obtains a frequency band from 0.7 to 1.4 GHz, exhibits a relatively high horizontal gain exceeding −2 dBi in the entire band, and possesses excellent omnidirectional radiation characteristics.