High-Isolation Two-Port UWB Antenna Based on Shared Structure

In this communication, a novel planar structure-shared diverse two-port ultrawideband (UWB) antenna with high isolation and common ground is proposed based on a new slot-loaded method. A tapered slot with an end-fire radiation pattern is etched in the top middle section of a coplanar waveguide (CPW)-fed printed monopole antenna to reduce its effects on the monopole mode. The two-port UWB antenna features diverse patterns which can fully cover the upper space. A nonuniformly symmetric-coupled coplanar waveguide (NSC-CPW) is introduced to enable the two sets of the feeding structures sharing a ground plane with minimum interaction. Due to the modal orthogonality, high isolation between the two ports is obtained without additional decoupling structures. The experimental results of the proposed multiple-input multiple-output (MIMO) antenna indicate that the isolation is higher than 31.4 dB and the diversity gain is approximately 10 dB within a wide frequency range from 2.98 to 10 GHz. Meanwhile, high realized peak gain (>2.5 dB) and good efficiency (>80%) are also obtained for both the ports.