Miniaturized Via-Free Magnetoelectric Dipole Antenna Fed by Substrate-Integrated Coaxial Line on Reactive Impedance Surface

A wideband via-free magnetoelectric (ME) dipole antenna is conceived for millimeter waveband applications. Herein, the electric dipole patch and a half-wavelength radiating slot are excited in phase on the patch layer by a substrate-integrated coaxial line (SICL) to fulfill the complementary conditions as an ME dipole. The proposed antenna omits the deployment of the vertically oriented shorted patch, which relieves the typical quarter-wavelength height constraint and fabrication complexity of the conventional ME dipole antennas. The antenna is further loaded with the capacitive reactive impedance surface (RIS) to achieve size miniaturization and bandwidth enhancement. The finalized dimension (excluding the RIS) is
$0.36\,\,\lambda _{0} \times 0.48\,\,\lambda _{0} \times 0.13\,\,\lambda _{0}$
, where
$\lambda _{0}$
denotes the wavelength in free space at the center frequency. A wide impedance bandwidth of 64.8% (17.1–33.5 GHz) is achieved for SWR
$\le2$
, in which the antenna gain varies from 5.9 to 8.8 dBi. Besides, a consistent unidirectional radiation pattern can be observed across the operating frequency band. In the sequel, the same antenna is aggregated into an eight-element linear array, which is fed by a designated eight-way SICL network. Finally, an active simulation has been performed to verify the ability of the array in beam scanning.