design of novel compact directional branch line coupler (blc) using microstrip coupled line for gsm application

We present here a novel model with compact size of directional branch-line coupler for personal communication. the branch-line coupler (blc) is based on microwave planar circuit operating at 900 mhz. a combination of two coupled open-circuit microstrip lines to create electrical coupling, and a single quarter-wave length is proposed to increase isolation between blc’s ports. the equivalent circuit of the proposed model is synthesized from l-c circuit and simulated by using a full-wave electromagnetic (em) simulation tool. a compact branch-line coupler (blc) is designed, analyzed, and tested using this technique. the size reduction is about 86% with comparable performance. the measurement results are in good agreement with the theoretical ones.