Abstract: A millimeter-wave broadband substrate integrated hybrid dielectric resonator antenna is provided. The hybrid antenna includes: a first dielectric substrate with high dielectric constant, a second dielectric substrate with low dielectric constant, and a third dielectric substrate with low dielectric constant sequentially stacked from top to bottom. The first dielectric substrate and the second dielectric substrate are adhered by a first adhesive sheet; the second dielectric substrate and the third dielectric substrate are adhered by a second adhesive sheet; a middle of a top surface of the second dielectric substrate is printed with a metal ring patch; a top surface of the third dielectric substrate is formed with a metal ground plane, and the metal ground plane is etched with a feed slot; and a bottom surface of the third dielectric substrate is disposed with a microstrip line.

Abstract: A low-calcium silicate cement consists of calcium oxide, silica, alumina, and iron oxide. A preparation method of the low-calcium silicate cement consists of: subjecting raw materials to crushing, joint grinding and uniform mixing to obtain a low-calcium silicate cement raw meal; calcining the above low-calcium silicate cement raw meal at 1050-1300° C. for 30-90 min, and cooling to obtain low-calcium silicate cement clinker; and levigating the above low-calcium silicate cement clinker till a specific surface area is 400-500 m2/Kg, thereby obtaining a low-calcium silicate cement.

Abstract: A low-calcium silicate cement, comprising: based on the total mass of oxides as 1, 50-60% of calcium oxide, 30-45% of silica, 2-6% of alumina, and 1-4% of iron oxide. A preparation method of the low-calcium silicate cement comprises: subjecting raw materials to crushing, joint grinding and uniform mixing to obtain a low-calcium silicate cement raw meal; calcining the above low-calcium silicate cement raw meal at 1050-1300° C. for 30-90 min, and cooling to obtain low-calcium silicate cement clinker; and levigating the above low-calcium silicate cement clinker till a specific surface area is 400-500 m2/Kg, thereby obtaining a low-calcium silicate cement.