In this work, a novel branch-line coupler is presented using a new type of microstrip cells. The proposed structure is
consisting of high and low impedance sections and a main small square closed loops. It operates at 2.4 GHz for WLAN
applications. Using the introduced structure, a good passband performance is achieved. An excellent phase balance closed
to ideal is obtained with a phase difference of 270 ± 0.037 between output ports. Furthermore, there are low return loss
and high isolation better than - 29 and - 30 dB respectively. Meanwhile, the designed coupler has a good insertion loss
and coupling factor. Despite of having a high performance, this coupler is relatively compact with an overall size of
0.037 kg2. The designing method is based on proposing an LC model of a basic microstrip cell and finding the effective
parameters to obtain a high performance. In order to validate the designing method and simulation results, the presented
coupler is fabricated and measured. There is a good agreement between the simulated and measured results.