Wideband Millimeter-Wave MIMO Antenna with a Loaded Dielectric Cover for High-Gain Broadside Radiation

Abstract

In a millimeter-wave terminal device, the use of a radome degrades the radiating performance of the broadside antenna, especially for the MIMO antenna system. In this study, a dielectric cover is de-signed and investigated to enhance the broadside gain of a millimeter-wave MIMO antenna, while keeping its wideband and high isolation performance. Firstly, a compact wideband ladder-shaped slot antenna is proposed with 21.9% bandwidth. The effectiveness of the dielectric cover design criteria over the wideband antenna is investigated. Then, this wideband antenna element is expanded to a 2 × 2 MIMO antenna by forming a center-symmetric structure and isolating it via the inserted metal vias. By loading the dielectric cover, this millimeter-wave MIMO antenna is verified with enhanced broadside gain for more than 2.1 dB. With the measured impedance bandwidth of 21.9% (57.0–71.0 GHz), peak broadside gain of 12.3 dBi, and high isolation over 15 dB, the proposed MIMO antenna is suitable for wireless gigabit terminal devices.