Coupled line directional coupler with round wires inside rectangular shield

Authors: Sychev A. N., Struchkov S. M., Sheerman F. I.

Annotation: The simulation and measurement results of the directional coupler with loose coupling of 20 dB for measuring systems operating in the frequency range of 1–4 GHz are presented. Coupled lines are formed as round wires, placed in the shield with a rectangular cross section. The model is built in a quasistatic approximation using the in-phase/out-of-phase excitation approach and Schwarz–Christoffel conformal mapping numerical technique. The doubly-connected cross-section regions are reduced to a simply-connected ones via magnetic slits, and round wires are approximated by polygonal boundaries. The electromagnetic field maps are given. The simulation results are in good agreement with experiment.

Keywords: directional coupler, coupled lines, round wire, loose coupling