A variable power divider circuit using the combine characteristic of the branchline coupler

Abstract

The proposed variable pawer divider in this paper is composed of one equal power 2-way Wilkinson power divider, two variable phase shifters with 90-degree phase variation to be connected two output paths of the 2-way power divider, and one branchline coupler to combine output signals of two variable phase shifter. The proposed variable power divider can theoretically have an arbitrary power division ratio ranging from 1: ∞ to ∞ :1 due to 90-degrees phase variation of two phase shifter. The proposed power divider circuit fabricates on laminated TLX-9(h=20 mil, er=2.5; Taconic) with a center frequency of 1.7 GHz. The power division ratio of the fabricated prototype varies from about 1:100 to 200:1, with an input reflection characteristic(S11) of below -16 dB, an insertion loss of about -1.0 dB, and an isolation characteristic of below -17 dB between two output ports in the range 1.65-1.75 GHz.