Novel Partially-Shielded Coplanar Waveguide with Metasurfaces for Liquid Crystals Tunable Delay Lines beyond 67 GHz

Artificial magnetic conductor (AMC) in the form of a partially corrugated internal wall of a metal enclosure is applied to optimise our pioneered liquid crystals filled partially shielded coplanar waveguide phase shifters for wavefront phase control beyond 67 GHz. The AMC introduces high impedance for the cavity-width-dependent higher-order modes and surface-wave radiation. This relaxes the within-a-half-guided-wavelength assumption on the cavity's width, thus allowing manufacturability by existing wire erosion whilst pushing the device's upper-frequency limit towards the W band (i.e., miniaturisation) without functional degradation. The first models developed in this work serve to navigate millimetre-wave experimentalists in formulating the optimal conditions for the liquid crystals based tunable device manufacturing, assembling, and experiments. For instance, the proposed AMC-assisted enclosure leads to excellent modularity (i.e., a fixed size of enclosure part compatible with devices operating at different frequency ranges), a decent improvement of yield (ease of assembling), and a significant reduction of misalignment-induced insertion loss by -3.2 dB at 60 GHz.