A Tactical Broadband High Power Fork-shaped Monopole Antenna

A miniaturized tactical high power omni-directional antenna in HF/VHF Band is here proposed. The antenna has been designed for wideband frequency 5:1 (20-100 MHz) applications. In addition, tactical requirements such as weight, no ground-plane, windproof, and pressure-resistant have been satisfied in this antenna design. The proposed antenna has been designed with a maximum length of about 1m that is equal to a fifteenth of wavelength (λ/15) in electrical size at 20 MHz. We have introduced a practical transformer to match the novel fork-shaped monopole antenna to 50Ω. As a result, the antenna is matched by measured VSWR almost less than 3 over the whole frequency band. The antenna results in a good omni-directional radiation pattern without adding a ground plane. The antenna has been fabricated and its gain varies from -5 dBi to 0 dBi. A good agreement is achieved between measurement and simulation with 100W power handling. Simulation results of the antenna have been obtained by using both HFSS Ansoft Designer and Advanced Design System softwares.