A Low-Cost High-Gain Filtering Patch Antenna With Enhanced Frequency Selectivity Based on SISL for 5G Application

This letter presents a high-gain filtering antenna with multiple radiation nulls and enhanced frequency selectivity using substrate integrated suspended line (SISL) technology. The presented antenna is composed of driven patches with slots, parasitic units, stubs, and stacked patches. The first radiation null is caused simultaneously at the upper band edge when the stacked patches are introduced to produce a resonance mode. The second radiation null is produced by the slots on the driven patches at the lower band edge. Due to the TM
₂₀
mode of the driven patches, the third radiation null is introduced at higher frequency. Owing to the stubs and parasitic units, the fourth radiation null is caused at lower frequency. The above four radiation nulls achieve excellent filtering performance with high selectivity. The measured results indicate the outstanding performance of the filtering antenna. The passband is from 3.28 to 3.79 GHz, perfectly covering the 5G-N78 band. The peak gain reaches 11.14 dBi, and the out-of-band rejection level is 17.8 dB. In addition, this filtering patch antenna is designed based on low-cost substrate FR4.