Coplanar waveguide antenna for surface acoustic wave temperature-pressure dual sensors

In this study, a wireless passive detection technique based on surface acoustic wave (SAW) temperature and pressure sensors is proposed. A dual-frequency planar monopole antenna with a relatively large bandwidth is designed using HFSS simulation software. The antenna is fed by a coplanar waveguide, and the bandwidth of the antenna is expanded using an elliptical monopole structure. Adding a bent patch and extending the length of the patch based on the wide bandwidth produces two resonance frequencies of 191.5 MHz and 221 MHz with a bandwidth of 2.2 MHz and 12.5 MHz, respectively. The physical dimensions of the antenna are 100 × 100 × 1 mm3. The fabricated antenna comprises an alumina insulating layer on the surface and high-temperature-resistant metallic materials as the substrate and radiating layer, respectively. Comparative simulation and physical test experiments were conducted for the fabricated antenna from room temperature to 1000 °C to ensure high-temperature resistance under high-temperature impact and to fulfill the wireless test requirements of the temperature–pressure dual-parameter integrated SAW sensor. A modified and upgraded JT1500 high temperature–pressure composite test system was utilized for testing the wireless passive SAW sensors. The proposed sensor-antenna integrated structure can be used for temperature and pressure monitoring in harsh environments.