Abstract
The microstrip patch antenna exhibits frequency stability under temperature variations, making it suitable for applications in the Industrial Internet, resource extraction, structural health monitoring, and other fields. A low-profile complementary split ring resonator (CSRR) structure is introduced into the radiating patch of the antenna, confining the electric field energy within a small region inside the ring. This design significantly enhances the antenna's sensitivity to changes in the dielectric constant. The synergy between the patch antenna and the CSRR structure forms an efficient dual-resonance system. Operating in a dual-band mode increases spectral efficiency and adapts to multi-band communication networks. To develop a sensor for real-time temperature detection, we explored various feeding methods for the antenna and optimized the structural parameters of its components. During this process, we found that adjusting the length, width, and opening size of the CSRR can achieve controllable tuning of the sensor's operating frequency bands. We selected 99% pure alumina ceramic as the substrate material and utilized screen printing and high-temperature sintering techniques to solidify the heat-resistant silver paste into metallic patterns and ground planes. Experimental results show that the fabricated dual-band microstrip patch antenna sensor exhibits resonant frequencies of f(r1) = 2.50 GHz and f(r2) = 3.24 GHz at room temperature, consistent with simulation outcomes. As the temperature rises from 25 °C to 350 °C, the S11 curve shifts linearly to the left. The sensor achieves a notch depth of -42 dB, a quality factor of 1413, and a maximum sensitivity of 183 kHz/°C. It also demonstrates excellent performance in stability and repeatability tests, with both resonance points accurately characterizing temperature parameters. The designed dual-band microstrip patch antenna sensor offers superior performance, meeting the requirements for multi-band temperature testing in practical applications.