A Millimeter-Wave 51% Bandwidth High-Gain 3-D-Printed Antenna Array Based on Optimized Multistage Phase Cancellation in Feed Network

A novel wideband high-gain air-filled waveguide-fed antenna array is presented for millimeter-wave applications. A design scheme based on the optimized multistage phase cancellation with low complexity is investigated, which is able to weaken the undesirable in-phase superposition of small reflections in the array geometry, thus significantly improving the achievable bandwidth of the large-scale array. The phase delay required for the proposed design method is obtained by introducing U-shaped bent waveguides in the feed network. Wideband
$1\times2$
sub-arrays and E-plane waveguide T-junctions are also designed to build the array. A
$16\times16$
array in the Ka-band is manufactured by employing metallic 3-D printing technology, which realizes excellent operating characteristics, including a bandwidth of 51.5%, a gain of up to 34.6 dBi, and stable unidirectional radiation patterns with cross polarization of less than −40 dB. The operating band of the proposed array covers multiple bands for 5G simultaneously, including n257, n258, n260, and n261. The proposed design method and antenna array would be attractive for emerging millimeter-wave applications.