A 28 GHz Band Compact LTCC Filtering Antenna with Extracted-Pole Unit for Dual Polarization

Abstract

This paper proposes a dual-polarized filtering antenna with extracted-pole unit (EPU) using LTCC substrate. The EPU realizes the high skirt characteristic of the bandpass filter with transmission zeros (TZs) located near the passband without cross coupling. The filtering antenna with EPU is designed and fabricated in 28 GHz band for 5G Band-n257 (26.5-29.5 GHz). The measured S₁₁ is less than -10.6 dB in Band-n257, and the isolation between two ports for dual polarization is greater than 20.0 dB. The measured peak antenna gain is 4.0 dBi at 28.8 GHz and the gain is larger than 2.5 dBi in Band-n257. The frequency characteristics of the measured antenna gain shows the high skirt characteristic out of band, which are in good agreement with electromagnetic (EM)-simulated results.