A Hydantion epoxy resin gel casting of MgTiO3-CaTiO3 ceramics and its application for 5G/6G waveguide filter

Microwave dielectric ceramics, as a novel electronic material, had been extensively utilized in the fabrication of radio frequency components for communication systems, including filters, dielectric antennas, and radar applications. While dry pressing remained the most prevalent method for filter fabrication, this study proposed an innovative gel casting system for manufacturing ceramic waveguide filters. The developed system employed Hydantion epoxy resin (HER) as the gelling agent, polyethyleneimine (PEI) as the curing agent, and MgTiO 3 -CaTiO 3 (MCT) ceramic powder (exhibiting dielectric properties of ε r  = 20.5, Q×f  = 55,000 GHz, and τ f  = ±10 ppm/°C) as the dielectric material. Experimental results demonstrated that incorporating 13 wt.% Hydantoin epoxy resin with 0.7 wt.% polyacrylic acid (PAA) dispersant yields a well-dispersed ceramic slurry containing 80 wt.% solid loading. After drying, the green body was sintered at 1400 °C for 3 h at air atmosphere. This process resulted in densified samples with homogeneous microstructure and optimized microwave dielectric properties. Building upon this foundation, a fourth-order waveguide filter was designed and fabricated with a center frequency of 3.5 GHz, bandwidth of 300 MHz, and return loss exceeding 15 dB. Compared to conventional dry pressing techniques, the gel casting approach demonstrated distinct advantages in simplified processing and cost-effectiveness. Its superior near-net-shape forming capability for complex geometries proved potential applications in next-generation 5G/6G microwave devices.