Design of Differential Multi-Point Feeding Dual-Polarized SISL Antenna Based on CM Analysis

Dual-polarized antennas are required in the current mobile communication to increase the channel capacity and reducing multi-path effects. Utilizing characteristic mode (CM) analysis, this paper presents a five-patch substrate integrated suspended line (SISL) antenna with suppressed unwanted higher-order modes, and achieves an enhanced bandwidth by using differential multi-point feeding (MPF) systems. Compared to single-point feeding systems, the proposed dual-polarized SISL antenna with the MPF system demonstrates a bandwidth 1.87 times wider. The novel SISL feeding system incorporates two pairs of differentially-fed branch line feed structures. A prototype of the proposed differential-fed antenna is fabricated and measured, showing good agreement between simulated and measured results. The dual-polarization SISL antenna can achieve realized gain from 8.1 dBi to 10.8 dBi within a working frequency from 3.17 GHz to 3.61 GHz (12.98%). Moreover, utilizing low-cost substrates, the proposed SISL antenna has the potential for 5G applications.