| 摘要 |
PROBLEM TO BE SOLVED: To provide a device for surely detecting the abnormality of an antenna by monitoring the signal level of a reflected wave by means of a reference signal transmitted at prescribed time intervals when a radio equipment operates and comparing it with a reference value. SOLUTION: In a base station S, the reference signal of a frequency band is transmitted from the base station S to the antenna A when a coaxial cable and the antenna are previously connected and are not connected at the time of an operation by an operator and a reflected signal is monitored in a monitor means M. In the monitor means M, the reflected signal of the frequency which is almost equal to the reference signal is received by a circulation part 2 as a monitor signal and it is inputted to a detection part 3. In the detection part 3, the reflected signal whose size gently fluctuates is converted into a DC signal containing a gentle fluctuation component and it is inputted to a waveform shaping part 4. Then, it is converted into a low frequency signal containing DC components and it is amplified in a DC amplifier part 5 and is outputted to a control part 6. The control part 6 compares the reference level stored in a storage part 7 with the input signal level and judges abnormality. |
