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

A wideband via-free magneto-electric (ME) dipole antenna is conceived for millimeter wave band 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 a 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 λ₀ × 0.48 λ₀ × 0.13 λ₀, where λ₀ denotes the wavelength in free-space at the center frequency. A wide impedance bandwidth of 64.8% (17.1 GHz - 33.5 GHz) is achieved for SWR ≤ 2, in which the antenna gain varies from 5.9 dBi 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 8-element linear array which is fed by a designated 8-way SICL network.