Design and performance of π guide directional couplers with very flat couplings

The use of the π guide is proposed for the construction of directional proximity couplers with a very flat response for the coupling. The dielectric configurations are analysed by Schelkunoff´s method and the effective constant dielectric method. The introduction of metallic walls in a dielectric proximity coupler allows us to eliminate the additional couplings in the curved zones, couplings which depend heavily on the frequency, and reduce the radiation losses.