Microstrip Antenna Design and Its Application in Moisture Detection

Moisture content is a critical parameter during processing and storage. Although conventional microwave-based moisture detection methods enable rapid and non-destructive measurement, they are often hindered by high cost and susceptibility to design limitations and environmental fluctuations. In this study, a partial ground plane technique combined with a beveled partial ground and corner truncation topology is employed to enhance antenna architecture. By accounting for the nonlinear relationship between antenna dimensions and operating bandwidth, the bandwidth is significantly broadened without increasing the antenna footprint. A novel microstrip antenna is developed using low-cost epoxy resin (FR4) as the substrate. To address the instability and narrow bandwidth often associated with microstrip antennas, an electromagnetic simulation model was constructed using HFSS. This model characterizes the relationship between dimensional parameters and bandwidth, facilitating antenna optimization. Simulation results demonstrate that the operating frequency remains stable at 915 MHz, while the operating bandwidth is expanded from 0.91-0.92 GHz to 0.6-1.1 GHz without increasing the antenna size, thereby satisfying the requirements for material moisture detection. The proposed antenna is integrated into the moisture detection circuit developed in this study, and its stability is evaluated under various environmental conditions. Results indicate that the novel microstrip antenna achieves high detection performance and is robust against environmental variations, while offering reduced fabrication costs. This study provides a new direction for the miniaturization and cost reduction of moisture detection systems.