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

Abstract

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 <inline-formula> <tex-math notation= LaTeX >$2 \\times 2$ </tex-math></inline-formula> slot subarray is optimized to confine the <inline-formula> <tex-math notation= LaTeX >${H}$ </tex-math></inline-formula>-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 <inline-formula> <tex-math notation= LaTeX >$8 \\times 8$ </tex-math></inline-formula> radiation slots at the <italic>Ka</italic>-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.