Planar Dual-Band Branch-Line Coupler With Large Frequency Ratio

Lei Xia,Baidenger Agyekum Twumasi,Shan-Shan Gao,Peng Liu,Jia-Lin Li

doi:10.1109/access.2020.2974235

Abstract

This work presents a novel planar branch-line coupler topology developed for dual-band operation using an E-shaped impedance transformer network to supplant the conventional microstrip line. Explicit closed-form design equations for dual-band operation are derived using the ABCD matrices. The studied coupler features a large dual-band frequency ratio with a compact size. A prototype coupler centered at 1 and 8 GHz is first presented and experimentally examined to demonstrate the large frequency ratio. Further, another prototype coupler centered at 2.4 and 5.2 GHz for potential WLAN applications is also developed and experimentally characterized. Measurements and simulations for both prototype couplers show good performance within the studied dual-band frequencies.

Highlights

The importance of microstrip branch-line couplers in microwave/radio frequency components and many applications have been as a result of the increase in multi-band components and system applications [1]–[8]
Dual-band communication systems have been on the increase, resulting in high demand for dual-band components such as branch-line couplers
For the design of branch-line couplers with dual-band operations, early work was reported by using π-shaped network [9], and recently by using the coupled-line stub based π-shaped structure [10]

Summary

Introduction

The importance of microstrip branch-line couplers in microwave/radio frequency components and many applications have been as a result of the increase in multi-band components and system applications [1]–[8]. INDEX TERMS Dual-band, branch-line coupler, E-shaped impedance transformer, large frequency ratio. For the design of branch-line couplers with dual-band operations, early work was reported by using π-shaped network [9], and recently by using the coupled-line stub based π-shaped structure [10].

Results

Conclusion