WIDEBAND DUAL-POLARIZED SIW CAVITY-BACKED PATCH ANTENNA WITH MULTIMODE CHARACTERISTICS

A new wideband dual-polarized patch antenna using substrate-integrated waveguide (SIW) technology is proposed in this paper. The antenna is composed of a patch radiator and a square SIW cavity. The square patch is internally embedded in the square SIW cavity with a surrounded slot. A pair of L-shaped probes are used for the excitation of the orthogonal linearly-polarized signals. The dominant resonant mode of the square patch resonator (TM010) and the modes of the SIW cavity (TE110 and TE120/TE210) are employed to achieve a wide impedance bandwidth under these resonances. By introducing two shorting pins, the isolation between two feeding ports can be enhanced to more than 21 dB. The resonant properties of these modes are investigated based on the cavity model theory. Then, their resonant frequencies are discussed to provide information for designing and optimizing such an antenna. For demonstration, a prototype is fabricated and measured. The measured results show that the proposed antenna achieves a wide impedance bandwidth about 66.7% (3.71–7.43 GHz) and 70.9% (3.58–7.52 GHz) for horizontal and vertical polarizations, respectively. A stable gain in the range of 7.15 to 8.03 dBi is obtained within the operating band. Due to the SIW cavity-backed structure, the antenna shows unidirectional radiation patterns and low back-lobe radiation at the resonant frequencies. Thus, the antenna is highly suitable for the base station antenna that is required to cover the bandwidth of 5.5 GHz WiMAX and 5.2/5.8 GHz WLAN systems.