Performance Optimization of Planar Directional Coupler

Directional coupler is a passive microwave device which is actively used in most of the microwave circuits such as modulator, antenna feeder network, duplexer etc. and needs a special attention towards the design philosophy as well as optimization of various key parameters critically in order to improve their performance for large verity of applications. This article is focused about the basic design concept of single section and multi-section directional coupler using complex mathematical equations, simulation using formulated results and optimization of various influencing parameter of coupler such as coupling factor, bandwidth, substrate permittivity, branch impedance etc. which results into determination of key performance indicators of a coupler such as insertion loss, return loss etc. in order to optimize the directional coupler for required application.