Pattern Diversity Antenna for 5G-NR Application Based on Closely-Spaced Semi-Circular Slots

In this study, a dual-feed polarization diversity antenna with a broadside or conical radiation pattern is proposed for fifth-generation (5G)-NR applications. The antenna’s design incorporates a radiator created using a circular slot, segmented into two semicircular slots by a protruding stub. By adjusting the phase difference applied to these two semi-circular slots, different radiation patterns within the same frequency band can be achieved. A modified 180° rat-race coupler served as the feed structure. By analyzing current distribution and E-field distribution, the phase difference formed in the two semi-circular slots according to the input terminal is confirmed. The measurement results showed that the proposed antenna exhibited polarization diversity characteristics across a bandwidth of 12.7% (
$3.24\sim 3.7$
GHz), with isolation exceeding 25 dB between the two input terminals. In this case, the measured gains are 5.2 dBi for Port 1 and 3.5 dBi for Port 2.