A Wideband VHF Horizontal Polarized Omnidirectional Square Loop Antenna

A novel double-layer square loop antenna operating at VHF band with omnidirectional horizontally polarized radiation pattern has been designed. The antenna consists of a square loop antennas loaded with capacitors, a parasitic loop, a LC matching network and a wideband 1-to-2 power divider. To generate horizontal polarized omnidirectional radiation pattern, periodical capacitors and the 1-to-2 power divider allow current along the loop to remain in phase and uniform. The introduction of a parasitic antennas can increase the bandwidth by 40%, and the LC matching network further doubled the impedance bandwidth of the antenna. Simulated results show the antenna obtains wide 10 dB return loss bandwidth of 11.9% (59.10MHz-66.26MHz) and good omnidirectional radiation pattern with low gain variation less than 1.1dB, and minimum gain is 1.67dB.