Cold-sintered Na2WO4-Ni0.2Cu0.2Zn0.6Fe2O4 ceramics with matched permittivity and permeability for miniaturized antenna

(1-x)Na2WO4-xNi(0.2)Cu(0.2)Zn(0.6)Fe(2)O(4) (NWO-NCZO) ceramic composites (x = 0-0.6) were successfully prepared by the cold sintering method under a uniaxial pressure of 200 MPa at 150 degrees C for 30 min. The microstructures and electromagnetic properties of (1-x)NWO-xNCZO ceramic composites with different NCZO contents have been systematically investigated. The obtained biphasic NWO-NCZO ceramic composites possess dense microstructures. The 0.4NWO-0.6NCZO ceramic composite exhibits a matched relative permittivity and relative permeability of around 8 in the frequency range from 10 to 200 MHz, which is beneficial for impedance matching between antenna and free space. A prototype of microstrip antenna based on the developed NWO-NCZO ceramic composite is designed and to demonstrate its application in miniaturized antennas. The simulation results revealed that the size of the radiation patch of the antenna can be reduced by 60% yet with bandwidth being enhanced 26.5 times when the 0.4NWO-0.6NCZO ceramic composite is selected as the substrate instead of pure NWO ceramic.