Miniaturized Wideband CP Antenna Based on Metaresonator and CRLH-TLs for 5G New Radio Applications

This article presents a detailed study on an interesting compact wideband CP antenna using a novel split-ring resonator (SRR) and composite right-/left-handed transmission lines (CRLH-TLs). A novel vertical SRR made by the metallic sheets and PCB substrate is proposed, which achieves substantial size reduction. To obtain wideband CP radiation, a novel 3 dB branch-line coupler using dispersion engineered CRLH-TL is employed as the feeding circuit. The vertical SRR and CRLHTL-based feeding network are analyzed by their own equivalent circuit models. A single-fed CP antenna and a dual-CP (LHCP/RHCP) antenna with a compact size of 0.277 λ0 × 0.277 λ0 ×0.033 λ0 at 3.30 GHz are implemented, respectively. For the dual-CP antenna, both the measured -10 dB |S11| bandwidth and 3 dB axial ratio (AR) bandwidth cover the 5G N78 band (3.30-3.80 GHz, 14.1%) quite well. In addition, the measured peak gain and radiation efficiency are greater than 5.4 dBic and 77% (-1.1 dB), respectively. It shows attractive features including a miniaturized size, low-cost, wide bandwidth, and good CP performance, appearing as good candidates for fifth-generation new radio (5GNR) communication systems.