Millimeter-Wave Low-Profile Tri-Band Filtering Antenna Based on Substrate Integrated Waveguide

In this letter, a low-profile tri-band filtering antenna based on substrate integrated waveguide (SIW) technique is proposed. The proposed closed-loop stacking topology of the SIW cavities creates multiple paths for coupling among them to effectively excite high-order modes and achieve tri-band filtering response. The TE201, TE301, and TE401 modes are excited to produce three passbands. The three passbands can be flexibly controlled by manipulating the aspect ratios of the cavities and a pair of perturbation vias introduced in the SIW cavity. Moreover, a radiation slot etched at the bottom of the whole SIW cavity achieves stable tri-band radiation by cutting the currents of the passband modes. For demonstration, a prototype has been fabricated and measured. Experimental results show that the antenna has three working passbands centered at 24.1 GHz, 29.9 GHz, and 36.2 GHz, with a peak gain of 5.5 dBi, 5.8 dBi, and 9.7 dBi, respectively.