An innovative low-noise directional borehole radar system is in development. Harsh and changing operating environments are a challenge to the low-noise sensitive electronic design. Additionally a system with such high sensitivity is susceptible to temperature changes and to component parameter variations. Therefore a calibration module was developed to calibrate the overall measurement system with a test signal generator. This calibration includes channel matching for accurate direction detection and sampling clock correction. After a brief introduction, testing and calibration methods are introduced. Additionally measurement results and figures depicting the practical results achieved so far are included.
The foundation for radar systems in general was laid by Christian Hülsmeyer when he obtained the worldwide first patent in radar technology on April 30, 1904 (patent DE 165 546). Six years later Gotthelf Leimbach and Heinrich Löwy applied for a patent to use radar technology to locate buried objects with radar technology (patent DE 237 944). This system used surface antennas together with a continuous-wave radar. In 1926, a pulse radar system was introduced and filed for a patent (DE 489 434) by Dr. Hülsenbeck. The particular invention improved the depth resolution and is still widely used today.
The underground mining operation for raw materials is planned and monitored by geological measurements. One method is drill-core analysis, whereas borehole radar systems are primary tools to map the surrounding area of the borehole.