Millimeter-wave 45º 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 sub-array 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 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 GHz - 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.