Design of Miniaturized Four-way Power Divider with Predefined Sequential Phase Difference for Antenna Feed Network

The manuscript presents a miniaturized four-way power divider with a sequential phase difference of 90°. The proposed power divider is designed using one rat-race coupler (RRC) and two branch-line couplers (BLC). For the minia-turization three open stub conversion of a single transmission line technique with meandering has been used. A Four-way power divider for the frequency of 145.825 MHz is designed and fabricated to discuss the proposed concept. The measured result shows a low insertion loss of 6.7 to 6.8 dB at each output ports. Also, the return loss for each port is better than 20 dB. Isolation between different output ports are better than 30 dB. The measured phase imbalance at each port is not more than 3°. The fabricated circuit size is $0.265 \lambda_g \times 0.275 \lambda_g$.

I. Introduction

Power divider or couplers are one of the important components used in the design of many RF/Microwave circuits such as modulators, RF mixers, feed networks, RF amplifiers etc [1]. Out of different couplers, branch-line couplers (BLC) and rat-race couplers (RRC) are commonly used. The conventional BLC and RRC consists of different quarter-wavelength transmission line sections at the designed frequency, which result in a large circuit dimensions especially at low fre-quencies. But in satellite and wireless communication, weight and size is the limitation. In literature, many methods have been proposed to design the miniaturized power divider.In [2] the defected ground structure (DGS) is chosen to design a miniaturized coupler, but it requires some minimum air space volume underneath to perform. Three stubs conversion of a single transmission line technique has been used in [3] to achieve compact rat race coupler, but this technique is not so useful for low frequency based BLC as dimensions of stub lead to a overall size comparable with conventional one.