Design of compact strip-line directional couplers for high power operation within frequency band 4–12 GHz

Abstract

A novel compact easy-to-manufacture design of 20 dB directional coupler has been proposed for a high power operation within frequency band 4–12GHz. In order to obtain the broadband frequency response a three-section asymmetric coupled strip-line directional coupler has been chosen. The periodic structures are introduced on the outer edges of coupled strip-lines to improve directivity and isolation of coupler. The successfully fabricated and tested coupler shows high electrical performances. The proposed 20 dB directional coupler provides within frequency band 4–12 GHz the coupling characteristic imbalance 0.5 dB, isolation 35 dB, directivity 15 dB and VSWR < 1.35. The allowable input power of directional coupler is up to 100 W. The coupler dimensions are 39 × 35 × 26 mm.