Orthogonal-Mode Decoupling Antenna Pair Based on Asymmetric Non-Differential Feed Mode

Abstract

This paper presents an orthogonal-mode decoupling antenna pair based on asymmetric non-differential feed mode. The main structure of the proposed antenna pair comprises a monopole antenna and a dipole antenna, placed above the ground plane. Antenna pairs realize decoupling property by the modal orthogonality of these two independent antenna elements without additional decoupling components, even though these two antenna elements share the same space in the same location. In our approach, the dipole antenna is fed by a coupling branch at one side of the dipole arm, avoiding the differential feed scheme at both sides that requires a balun chip. In order to ensure good isolation between the dipole and monopole antennas operating in the same frequency band, an asymmetric dipole is designed. The antenna pair shows an impendence bandwidth of 3.05-3.9 GHz by employing the orthogonal-mode design scheme, the maximum isolation across the target frequency band can reach more than 21 dB. The simulation results show that the envelope correlation coefficient between two antenna ports is lower than 0.03. The total efficiencies of the monopole and dipole antennas are 58%-90% and 59%-89% across 3.05-3.9 GHz, respectively. The proposed design scheme has the advantages of simple feed, high integration, and simple implementation, so it has potentials for 5G MIMO applications.