Microwave dielectric properties of CaLnNbWO8 (Ln = La, Nd, and Sm) ceramics for dielectric resonator antenna application

Abstract Scheelite‐type microwave dielectric ceramics (MWDC) are of great appeal as they possess a low dielectric constant ( ε r ) and a high quality factor ( Q × f ). In addition, the development of 5G communication has caused an urgent demand for electronic devices, such as dielectric resonant antennas. Hence, the feasibility of optimizing the dielectric properties of the CaWO 4 ceramics by substituting rare earth ions at the A site was studied. The study revealed that the covalency, lattice energy and bonding energy of W─O were stronger than those of Ca─O, indicating that the W─O bonding significantly influences the adjustment of the dielectric properties of the investigated ceramics. An optimum microwave dielectric performance was achieved for CaNdNbWO 8 ( ε r = 12.78, Q × f = 55,160 GHz, and TCF = 8.53 ppm/°C). This work lays a solid theoretical foundation for improving the microwave dielectric properties of CaWO 4 samples. Notably, a cylindrical dielectric resonator antenna (CDRA) with high simulated radiation efficiency (96.6%) and gain (5.65 dBi) at the center frequency (7.25 GHz) was fabricated based on the CaNdNbWO 8 ceramics. Considering the merits of low loss and good temperature stability, CaNdNbWO 8 ceramics could be expected as promising candidate for 5G and future millimeter‐wave applications.