Miniatured Substrate Integrated Waveguide Hybrid Coupler Loaded with Resonance Type Metamaterial

The paper introduces a new small-sized metamaterial-loaded wideband substrate integrated waveguide hybrid coupler designed for millimeter wave applications, operating within the frequency range of 28 GHz to 38 GHz. A complementary split-ring resonator is incorporated on the top conducting plane of the hybrid coupler to improve isolation, return losses, and coupling, and achieve equal power division between the input and through ports. The Roggers 5880 dielectric material with a dielectric constant of 2.2 and a thickness of approximately 1.6 mm was used to grow the structure. The simulation took place in CST Microwave Studio. The proposed structure yields a transition co-efficient of around −4 dB and accomplishes equal power splitting with a ∼90degree phase shift between the input and through ports. The isolation between the input and isolated port was measured at a maximum of −35 dB, and it provides improved return losses of about −25 dB across the frequency range. This type of resonance metamaterial-loaded hybrid coupler demonstrates a broader bandwidth and also exhibits bandpass filtering characteristics. The proposed coupler takes up a total space of 10.7 × 19 × 1.67 mm 3 . In terms of advantages, the proposed hybrid coupler has a low profile, minimal losses, effective power splitting, good coupling, and isolation. It can be easily integrated into microwave and millimeter-wave planar circuits, particularly in beam-forming networks.