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In this paper, (1-x)LiWVO6-xK2MoO4 (LWVO-KMO, x = 60, 65, 70, 75, 80, 90 wt%) composite ceramics with >92% relative density were prepared by cold sintering at 160 °C under a uniaxial pressure of 300 MPa for 1 h. X-ray diffraction (XRD), Scanning electron microscopy (SEM) and Raman spectroscopy demonstrate that LWVO and KMO coexist without other impurities. (1-x)LWVO-xKMO composite ceramics exhibit relative permittivity (er) ranging from 6.8 to 8.5, microwave quality factor (Q × f) ranging from 2050 to 7182 GHz, and temperature coefficient of resonant frequency (τf) ranging from −49 to +25 ppm/°C. Based on cold sintered 30 wt%LWVO-70 wt%KMO composite ceramic with er ~7.8, Q × f ~4514 GHz, and near zero τf ~1.3 ppm/°C, a prototype microstrip patch antenna was designed and manufactured. Through testing, it shows excellent antenna performance with a center frequency of 6.58 GHz, a bandwidth of 170 MHz (−10 dB) and a total efficiency of up to 89.5%.

The crystal structure, microstructure and dielectric properties of layered perovskite structured La 5− x Sr x Ti 4+ x Sc 1− x O 17 ( x =0–0.8) ceramics prepared by a solid state reaction route were investigated. X-ray diffraction and Raman spectroscopy analysis revealed the formation of single phase orthorhombic ( Pnnm ) symmetry. The microwave dielectric properties ( e r , Q×f o and τ f ) of samples have been investigated as a function of composition. e r and τ f increased while Q×f o decreased with an increase in x . The sample x =0.6 exhibited e r =54.8, Q×f o = 12,260 GHz and τ f =6.7 ppm/°C which may be a suitable candidate material for dielectrically loaded antenna applications. The complex impedance spectroscopy analysis of the sample x =0.6 revealed that the sample is highly insulative with two electro-active regions (bulk and grain boundary).