A Compact Dual-Band Radiator-Shared Antenna With Enhanced Isolation and Flexible Frequency Ratio Regulation

In this article, a radiator-shared duplex antenna (RSDA) with enhanced isolation, flexible frequency ratio regulation, and compact size is proposed for applications in multiband/standard communication systems. The radiator-shared design is based on a shaping scheme by utilizing a parasitic resonator to make the lower-band and higher-band antennas have the same radiation structure. Customized feeding methods are employed to individually excite the high-order substrate integrated waveguide (SIW) cavity mode and the fractional-order patch mode, enabling dual-band operation and allowing a flexible frequency ratio regulation from 1.3 to 1.7. The proposed RSDA eliminates the need for decoupling structures or additional duplexing/filtering circuits. Isolation enhancement of over 24 dB is accomplished by exploiting the layered feeding architecture, shielded sidewalls, and a high-pass SIW feedline to suppress the feedline coupling, surface wave interference, and out-of-band signal propagation, respectively. For verification, a prototype of the proposed RSDA was measured, demonstrating dual-wideband operation that encompasses the targeted 5G/Sub 6G n78 band (3.3–3.6 GHz) and n79 band (4.8–5 GHz). The prototype achieved a peak gain of 5.3 dBi at 3.45 GHz and 7.4 dBi at 4.95 GHz, while exhibiting a high isolation level exceeding 53 dB and good radiation patterns.