A Balun Bandpass Filter to Facilitate the Design of Dual-Polarized Dipole Antenna

He Huang,Muhammad Ramlee Kamarudin

doi:10.1155/2020/6209081

He Huang, Muhammad Ramlee Kamarudin

Open Access

https://doi.org/10.1155/2020/6209081

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Abstract

A dipole antenna based on a balun bandpass filter (BPF) is developed in this paper. The balun BPF employs two U-shaped resonators settled on the left side of the open-circuited transmission line and two L-shaped stubs to produce signals with equal amplitude and inverse phase. In this way, the volume of the balun BPF is reduced by half, and the distance between two output ports is dramatically decreased. Then, the balun BPF is integrated with a dipole. Instead of the traditional Γ-shaped line with a wide balun ground, two thin microstrip lines with width of 1 mm are adopted to connect the dipole and the balun BPF. The antenna bandwidth is further extended due to the fusion of the resonance of the dipole and balun BPF. As a result, the proposed antenna can operate from 4350 to 5025 MHz (covering the n79 band of 5G NR, 4400 MHz–5000 MHz), yielding a good filtering performance in the stopband. The measured half-power beamwidth is ranging from 61° to 63° and the measured gain is ranging from 7.95 to 8.5 dBi in the passband. This new balun BPF and the dual-polarized dipole based on it have great potential to be applied in 5G MIMO systems.

Highlights

In many radio frequency wireless systems, the bandpass filter (BPF) has been widely used
Two thin microstrip lines with width of only 1 mm are adopted to connect the dipole and the balun BPF, as shown in Figures 5 and 6. Another benefit of this design is that the antenna bandwidth can be further extended due to the resonance merged between the dipole and balun BPF
The BPF is connected to the antennas to suppress the unwanted signals

Summary

Introduction

In many radio frequency wireless systems, the bandpass filter (BPF) has been widely used. E device in [15] employs a four-way out-of-phase resonator, coupling the energy from the slots to the patches and rendering a filtering response at S-band. All the antennas involved in [13,14,15,16] are patch type, and all of them are using the coupled lines with capacitive loads to implement the bandpass filter. A dual-polarized antenna based on such filtering power divider which could operate from 4350 MHz to 5025 MHz is fabricated and investigated. It has a good frequency selectivity at the band edge. It has a good frequency selectivity at the band edge. e proposed antenna could be very promising to weaken the interference between the different antennas in 5G systems

Design of the Balun BPF

Dipole Antenna Integrated with the Balun BPF

Conclusion