Design of CRLH-TL Based Compact Hybrid Coupler Loaded With S-Shaped Slot

This manuscript presents a Compact right-left handed (CRLH) structure based hybrid coupler. It consists S-shaped slot, loaded on each quadrant of circular patch hybrid coupler and via at the centre to provide compactness. The proposed coupler provides coupling level 0.1 dB at resonating frequency 3.2 GHz. It provides 3 dB fractional bandwidth of 25% from 2.7 GHz to 3.5 GHz. Proposed coupler provides return loss of 19.0 dB with isolation value of 25.0 dB at operating frequency. The size of designed structure is 0.17λ
₀
×0.14λ
₀
(16.0 mm×13.6 mm) at frequency of 3.2 GHz, which provides compactness. An equivalent lumped circuit model has obtained and its response having good agreement with EM simulated result. Parametric study has supported out to demonstrate the flexibility of designed hybrid coupler.