In order to meet the requirement for wave transparent materials, the porous Si3N4 materials with high
strength and low dielectric constant were fabricated by gel casting method. The microstructure, dielectric properties,
wave transmittance and flexural strength were investigated. The results show that the flexural strength of porous Si3N4 is up to 50 MPa with dielectric constant of 2. 3 to 2. 8. At the same time, the materials have steady high temperature
dielectric properties and good wave transparent properties.