Gain-Enhanced SIW Cavity-Backed Slot Antenna with Arbitrary Levels of Inclined Polarization

This letter describes a gain enhancement method for a dual-polarized substrate integrated waveguide cavity-backed slot antenna by using a high-order cavity resonance to generate arbitrary levels of inclined linear polarization (LP). To do so, the metal posts are embedded in a main cavity to excite the TM220 mode of the cavity and control the amount of coupling to generate adjustable inclined linear polarization. To validate the simulated results, an antenna is designed, manufactured, and tested. The proposed antenna exhibits high front-to-back ratio (F/B) of more than 20 dB in the broadside direction and a relative gain of 6.9 dBi at the resonant frequency. The antenna can also provide an adjustable inclined LP with an aspect ratio of Exmax/Eymax ranging from 0.23 to 4. The proposed method can also be utilized to achieve even higher gain by exciting higher order mode cavity resonances, such as TM440 and TM660. The proposed antenna exhibits the advantages of simple feed network and more compactness compared with the SIW cavity-backed slot antenna/array that has the same gain with inclined polarization.