A Compact Wideband Multi-Beam Antenna for VHF/UHF Directional Networking Applications

We propose a wideband multibeam circular array antenna for directional networking applications at VHF/UHF frequencies. We introduce a directional antenna element by combining the radiation patterns of a monopole and a loop element. Combining the figure-eight-shaped and omnidirectional radiation patterns of the loop and the monopole antenna results in a directional antenna element. We demonstrate that a significantly larger bandwidth can be achieved by moderately relaxing the size constraints placed on the antenna element. A circular array consisting of eight of these radiating elements was developed. This array has a low profile, fitting in a 4
$\times $
4
$\times $
1 ft3 volume. The antenna shows a well-matched frequency response with S11 below −10 dB over an octave frequency bandwidth of 225–450 MHz. The good impedance matching of the array is maintained if the array elements are individually excited (e.g., to provide eight beams) or if multiple adjacent elements are excited together to provide fewer, more directional beams. We validated our simulation results by fabricating and experimentally characterizing a 3:1 scaled model of the proposed antenna. The proposed array can achieve gain values of 6–8 dBi within its operational bandwidth if each radiating element is excited individually. This gain increases to 10–12 dBi by exciting three adjacent elements.