| 摘要 |
<p>PROBLEM TO BE SOLVED: To enhance detection accuracy of water leakage, while facilitating the detection of Doppler frequency. SOLUTION: An antenna 40 is provided with a metallic antenna box 42 and an antenna element 44. The antenna element 44 has a width d and a length e which equal one half a wavelengthλof electromagnetic wave being radiated into the ground and constitutes a half-wave planar dipole antenna element. The antenna box 42 is a cavity resonance type box, where two sides l, m of the bottom face and the height h have a basic dimension equal to one half of the wavelengthλ.</p> |
