Design of a Compact Direction-Finding Antenna Using Single-Radiator Multiple-Port for UWB Mobile Applications

This paper proposes a compact ultra-wideband (UWB) direction-finding antenna with a single-radiator multiple-port (SRMP) design. The proposed antenna consists of a single-radiator, self-decoupling feed structure (SDFS), and via walls considering the limited mounting space for mobile applications. The SDFS is optimized to improve isolation characteristics between adjacent ports. To verify the feasibility, the proposed SRMP antenna is fabricated, and antenna performance such as reflection coefficients, mutual couplings, and radiation patterns are measured in a full anechoic chamber. The SRMP antenna achieves a broadband of 2.1 GHz (from 6.3 GHz to 8.4 GHz) and a low mutual coupling of -21.22 dB at 8 GHz. In addition, a bore-sight gain of 0.78 dBi is measured at the target frequency of 8 GHz. To investigate the direction of arrival (DoA) estimation of the SRMP antenna, we utilize the Qorvo test board with the DW3000 chip, generally used in commercial UWB direction-finding systems. At distances of 1 m and 2 m, average estimated errors of 2.35 degrees and 2.13 degrees are obtained, respectively. These results demonstrate that the proposed compact SRMP antenna is suitable for UWB direction-finding systems of smart devices.