Backlobe and Sidelobe Suppression of a Q-Band Patch Antenna Array by Using Substrate Integrated Coaxial Line Feeding Technique

A low profile aperture-coupled patch antenna array with high front-to-back-ratio (FTBR) is designed at Q -band by using substrate integrated coaxial line technique, the intrinsic shielded enclosure of which is capable of constructing an equal-phase and amplitude-tapering feeding network with backlobe suppression. An illustrative example of a 6 $\times$ 6 patch antenna array is designed and fabricated with a 2 $\times$ 2 prior verification module by using multilayer liquid crystal polymer process. Measured results indicate that the array can achieve a gain of 17.6 dBi at 41.5 GHz and the first sidelobe levels is $-$ 24.1 dB in the E -plane and $-$ 20.4 dB in the H -plane. The holistic FTBR is better than 27 dB in both planes.