Wideband directional antenna system with different polarizations for wireless communication system

A novel directional antenna system with different polarizations is proposed for wireless communication system application in this paper. The proposed antenna employs modified E-shaped rectangular patch for vertical polarization and crossed dipoles for ±45° slant polarization. The vertically polarized (VP) element is formed by inserting a pair of wide slits at the boundary of rectangular patch with edge folded. The VP element is fed by using an L-probe feed, designed to work at the frequency range of 773-1013 MHz for GSM900 and other wireless communication systems such as GSM850 and LTE700 bands. Dual slant polarized (SP) elements are formed with two orthogonally situated dipoles with corner cut and slots on the patch, which yields a wide impedance bandwidth of 55.5% covering the frequency bands for 3G and LTE communication systems. A wideband diplexer is used to connect VP element and +45° SP element, forming a compact structure. Simulated and measured results show that peak gains of 8.0 dBi for VP element and 9.5 dBi for ±45° SP element, an isolation better than 26 dB over the working frequency bands are achieved. The cross-polarization levels in the azimuth plane for triple polarization states are lower than −14 dB.