Groove Gap-Waveguide Filter with Low-Loss and Dual-Band Capabilities for Satellite IoT Communication Networks Across K-band

This paper presents a dual-band groove gap-waveguide (GGW) filter that provides two separately adjustable passbands within a single-layer structure. The core contribution is a dual-cavity organization that uses two distinct cavity groups operating in the same TE₁₀₂ mode, together with novel I-shaped coupling slots milled in the top plate that serve as the primary mechanism for controlling inter-resonator coupling. This combination provides flexible per-band adjustment of center frequency and bandwidth without resorting to higher-order mode sequencing or multilayer stacks often used in prior GGW implementations, thereby simplifying fabrication and assembly. A prototype addressing space-to-Earth downlink bands exhibits passbands centered at 19.0 and 20.75 GHz, with 3-dB bandwidths of 400 and 280 MHz, respectively, and insertion loss <0.4 dB across both bands. Measured return loss is ≥15 dB, and the contactless GGW realization suppresses parasitic leakage while simplifying machining and assembly. Sensitivity analysis confirms tolerance to typical CNC variations in pin height, air gap, and slot dimensions, supporting reproducible performance. The proposed filter therefore provides a practical RF solution for satellite IoT payloads requiring low loss, spectral agility, and simplified fabrication. Relative to state-of-the-art GGW filters, it achieves a favourable trade-off among complexity, footprint, and electrical performance, facilitating scalable multiband K-band front-ends for emerging satellite IoT networks 1 .