“…It is reported that various anomalies of the electromagnetic field or the ionosphere have been observed before earthquakes. The frequency used to observe these phenomena ranges from ULF( 3Hz), ELF(3 3000Hz) or VLF(3 30kHz) (1) to HF(300 3000kHz) or VHF(3 300MHz) (2)- (4) . However, the microwave in GHz band has hardly been used.…”