Millimeter-Wave Endfire Magnetoelectric Dipole Antenna and Array With Horizontal Polarization and Wide Bandwidth

A horizontally polarized endfire magnetoelectric dipole (ME-dipole) antenna with a bandwidth of exceeding 80% is proposed at millimeter-wave (mmWave) frequencies. The antenna is fed by a substrate-integrated coaxial line (SICL), whose radial electric field distribution of the TEM mode is utilized to facilitate the excitation of a horizontally polarized ME-dipole antenna. The antenna consists of a planar bow-tie dipole array and a quarter-wave shorted patch implemented in a mesh-grid form. A wide impedance bandwidth of more than 88% and a 3-dB gain bandwidth of 81% are achieved. Moreover, by introducing top-loaded structures and air slits, the proposed ME-dipole element is further modified and applied to array designs, realizing a compact form factor and reduced mutual coupling. Finally, a
$1\times8$
ME-dipole antenna array fed by an SICL feeding network is designed, fabricated, and measured, experimentally demonstrating an impedance bandwidth of 61%, a gain of up to 13.2 dBi, and stable radiation patterns.