La(Mg_0.5−<i>_x</i>Me<i>_x</i>Sn_0.5)O₃-based (Me = Ca, Sr) dielectric resonator antenna for use in a wireless high-temperature sensor

Abstract

The microwave dielectric properties of La(Mg 0.5¹x Me x Sn 0.5)O 3 (Me = Ca, Sr) ceramics are studied, in order to develop a wireless dielectric resonator antenna temperature sensor. The microwave dielectric properties of La(Mg 0.5¹x Me x Sn 0.5)O 3 (Me = Ca, Sr) ceramics are determined using X-ray diffraction patterns, Rietveld refinement patterns, Raman spectra, and by observing the microstructures. La(Mg 0.5¹x Me x Sn 0.5)O 3 (Me = Ca, Sr) ceramics are prepared using a conventional solid state method. As the degree of substitution of Ca 2+ and Sr 2+ increases, the position of the A 1g (O) Raman mode shifts toward a lower frequency. The La(Mg 0.4 Ca 0.1 Sn 0.5)O 3 ceramic exhibits a minimum full width at half maximum for the A 1g (O) Raman vibration mode in the series of La(Mg 0.5¹x Me x Sn 0.5)O 3 (Me = Ca, Sr) ceramics. La(Mg 0.49 Ca 0.01 Sn 0.5)O 3 ceramics that were sintered at 1600°C for 4 h have an apparent density of 6.57 g/cm 3 , a dielectric constant (¾ r) of 19.9, a quality factor (Q©f) of 94,300 GHz, and a temperature coefficient at the resonant frequency (¸f) of ¹87 ppm/°C. The development process and test results for a dielectric resonator antenna temperature sensor that uses La(Mg 0.49 Ca 0.01 Sn 0.5)O 3 ceramics are recorded. The resonant frequency is 9.35 GHz and the 3 dB bandwidth measured at room temperature is 6.4 MHz. A sensitivity of ¹1.03 MHz/°C is achieved.