A Millimeter-Wave 48% Bandwidth High-Gain 3-D-Printed Antenna Array Using T-Junctions With Multiple Reflection Nulls

An innovative approach to designing millimeter-wave wideband high-gain large-scale antenna arrays is proposed with the use of waveguide T-junctions with multiple reflection nulls for building an H-type full-corporate feed network. By collaboratively optimizing the properties of the reflection nulls, the undesirable in-phase superposition of small reflections in the feed network can be weakened, thus improving the bandwidth of the array. The method of synthesizing wideband iris-loaded H-plane stepped waveguide T-junctions with three reflection nulls is investigated. A
$16 \times 16$
horn array in the Ka-band is designed based on the presented approach and manufactured by employing metallic 3-D printing technology. Excellent performance, including a wide bandwidth of 48.4%, a gain of up to 34.5 dBi, and symmetrical and stable radiation patterns in both the E- and H-planes, are experimentally verified. This work is feasible and convenient for the implementation of high-gain wideband antenna arrays, which is valuable to emerging millimeter-wave applications.