Miniaturized Quasi-Lumped Coupled-Line Single-Section and Multisection Directional Couplers

A class of lumped-element coupled-line directional couplers has been investigated. The paper discusses the influence of the number of coupler's subsections on the overall couplers' performance. The design procedure for calculating elements of the coupler for the chosen coupling C and the number of coupler's subsections has been proposed. The design procedure has been experimentally verified by the measurements of a single-section directional coupler. Also, an asymmetric two-section coupler not reported in the literature has been designed using a lumped-element technique, and the experimental results are shown.