Glass-Based Single-Layer Slow Wave SIW Filter With Embedded Composite Right-/ Left-Handed Resonator

This article presents a composite right-/left-handed (CRLH) loaded slow wave substrate integrated waveguide (SW-SIW) filter using through glass via (TGV) technology. The proposed glass-based topology integrates via holes and blind holes in a single-layer substrate, enabling the achievement of the SW effect. This miniaturization strategy can be flexibly combined with other miniaturization technologies. The size of the holes prepared using TGV technique is one-tenth that of printed circuit board (PCB), allowing glass substrate to be more competitive in millimeter-wave band. The propagation properties of glass-based SW-SIW are revealed first, and the designed third-order filter realizes more than 53% size reduction compared to conventional SIW cavity configuration. Subsequently, the CRLH resonator embedded in SW-SIW exhibits phase characteristics opposite to conventional parallel LC unit. Besides, the SW-CRLH resonator can facilitate the realization of fourth-order filtering function without enlarging the packaging size of the initial third-order filter. Furthermore, the glass-based filter with elliptic function response can achieve independent tuning of transmission zeros (TZs). As a prototype, a fourth-order millimeter-wave filter is designed, fabricated, and measured. The experimental results confirm the advancement of the manufacturing process and the feasibility of the miniaturization strategy.