A Dual-band Broadband Omnidirectional Antenna

In this paper, a dual-band wideband vertically polarized omnidirectional antenna operating in the VHF/UHF band is proposed. The low-frequency band of the antenna uses the ultra-broadband printed dipole antenna form, and the high-frequency band uses the broadband printed dipole collinear antenna array, The two frequency bands are synthesized by a two-way combiner and impedance matched by a matching network. The antenna frequency band covers two frequency bands: 225MHz-678MHz and 1.4GHz-1.8GHz. Antenna VSWR is less than 3 in the frequency band. Good omnidirectional radiationwith gain variations less than 0.8 dBi in the azimuth plane has been obtained. Dual frequency antenna gain about 0 dBi for low low frequency band and about 4 dBi for high frequency bands are achieved. The antenna has the characteristics of wide frequency band, high gain and light weight, and can provide good omnidirectional radiation characteristics in the working frequency band.