Developing a High-Power Metal-Plate Lens Antenna for Microwave Fracturing of Rocks

This study presents the design and experimental validation of a high-power metal-plate lens antenna for efficient microwave fracturing of rocks in the near-field. The antenna integrates a horn feed with a biconcave metal-plate lens to achieve extended working distances and enhanced power focusing. Through numerical simulations, the antenna demonstrated a maximum microwave power density of 22 W/cm(2) on diabase rock surfaces at 6 kW input power with a 36 cm irradiation distance. The reflection coefficient remained below -10 dB across irradiation distances of 20-50 cm, confirming robust energy transmission. Rock fracturing tests revealed that the antenna effectively induced thermal cracking at 36 cm, achieving a peak surface temperature of 270 degrees C after 4 min of irradiation. The results highlight the antenna's ability to maintain focused microwave energy over practical working distances, offering significant potential for deployment in tunneling and mechanical excavation where conventional antennas face limitations. This work advances high-power microwave applications in geotechnical engineering by addressing critical challenges in power delivery and operational range.