A $Ka$ -Band 3-D-Printed Wideband Stepped Waveguide-Fed Magnetoelectric Dipole Antenna Array

A novel millimeter-wave aperture-coupled magnetoelectric (ME) dipole antenna with a low-profile metallic geometry is proposed based on the 3-D printing technology. An impedance bandwidth of 53.7%, a gain up to 10.8 dBi, and stable unidirectional radiation patterns with the cross polarization of less than -38 dB are achieved by the antenna. Its operating mechanism and design process are studied in detail as well. In order to widen the bandwidth of the millimeter-wave fullcorporate H-plane air-filled waveguide feed network, a wideband H-plane stepped waveguide T-junction with a compact size is then investigated, which has a bandwidth of about 50% for the reflection coefficient of less than -20 dB. By combining the presented radiating element with the feed network, an 8 x 8 ME dipole array is designed, printed, and tested in the Ka-band. An enhanced bandwidth of 31%, symmetric radiation patterns with the cross polarization of less than -35 dB, and a gain varying from 25.5 to 28.5 dBi are experimentally obtained. The proposed design demonstrates the advantage of utilizing the 3-D printing method to improve the operating characteristics of the millimeter-wave antenna array and is attractive for the emerging wideband millimeter-wave wireless applications.