Millimeter-Wave 45° Linearly Polarized Corporate-Fed Slot Array Antenna With Low Profile and Reduced Complexity

A millimeter-wave 45° linearly polarized corporate-fed slot array antenna is presented in this communication. A key feature is the much reduced number of metallic layers and, therefore, the complexity of the array, as compared with other competitive designs. With the reduced antenna profile, high cross-polarization discrimination (XPD) and low sidelobe level (SLL) are still achieved by a combination of techniques. The back cavity of the 2 ×2 slot subarray is optimized to confine the H-field along the direction of the radiation slots, enhancing its XPD. Stubs are loaded in the same cavity to compensate for the phase imbalance, suppressing both cross-polarization and grating lobes without introducing additional metallic layers. Combining these features, the proposed array antenna demonstrates high performance with only three essential metallic layers. A prototype with 8 ×8 radiation slots at the Ka-band is implemented for demonstration. Experimental results show that the grating lobes are suppressed to below -30.5 dB, and the first SLL (FSLL) of less than -26.2 dB. XPD of more than 31.3 dB is achieved over the frequency range of 26.5-32 GHz. The peak gain of better than 25 dBi and antenna efficiency of over 71.7% are also obtained over the same frequency range.