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A new tri-band dual-polarised omnidirectional antenna is proposed. The dual-polarised antenna consists of a metal cuboid body with a vertical slot for horizontal polarisation (HP) and a rectangular back metal cavity with two folded horizontal slots for vertical polarisation (VP). A metal HP feedline is employed to coupling feed the vertical slot while a metal VP feedline is used to excite the two horizontal slots. Due to the coupling feed and the orthogonality between the vertical and horizontal slots, the dual-polarised antenna features three bands and a high isolation. Experimental results show that the tri-band dual-polarised antenna covers the Chinese Unmanned Aircraft System bands (840.5-845, 1430-1444 and 2408-2440 MHz) with reflection coefficients <−10 dB and isolation >32 dB. Good omnidirectional radiation patterns are observed for both HP and VP.

A dual‐band horizontally polarized (HP) antenna with omnidirectional radiation patterns is presented in this paper. The HP antenna is a vertical slot backed with a metal box, which is excited by a tapered feeding patch with a U‐slit for dual‐band operation. Good omnidirectional radiations are observed. A dual‐band dual‐polarized (DP) antenna is then developed by adding a dual‐band vertically polarized (VP) element to the HP element. The VP element is composed of two horizontal slots excited by a two‐branch feedline. The dual‐band DP antenna achieves an overlapped impedance bandwidth of 6% (2.34‐2.5 GHz) for the lower band and 15% (5.06‐5.91 GHz) for the upper band with an isolation of higher than 35 dB. Both the dual‐band HP and DP antennas are suitable to serve as WiFi/WLAN/ISM antennas for short‐range, low power wireless communications.

A new wideband dual-polarized (DP) quasi-omnidirectional antenna is proposed. The DP antenna consists of a vertical slot for horizontal polarization (HP) and a folded horizontal slot for vertical polarization (VP). A tapered strip is employed to coupling feed the vertical slot while a straight strip is used to excite the horizontal slot. Due to the coupling feed and the orthogonality between the vertical and horizontal slots, the DP antenna features a wide bandwidth and a very high isolation. The simulated isolation is higher than 70 dB, although the measured isolation is about 50 dB. As experimental results indicate, the DP antenna realizes an impedance bandwidth (BW) of 45% (1.7–2.73 GHz) with quasi-omnidirectional radiation patterns for both HP and VP. The DP quasi-omnidirectional antenna may be packaged into a radome with a shape of a blade for mobile applications in high-speed vehicles.