PURPOSE: To detect a liquid surface or level, by detecting an electromagnetic wave from a transmitting antenna in the form of variation in electromagnetic induced voltage at a receiving antenna according to fluctuations of the liquid level or surface of liquid or bulk material to be monitored which contacts the circumference of the transmitting antenna.
CONSTITUTION: When the transmitting antenna 3 uses an antenna bar and the receiving antenna 4 uses a receiving coil, a high frequency signal from an oscillating circuit 1 is impressed to the antenna bar 3. When this signal is detected by the receiving coil 4, the voltage induced across the coil 4 varies with the specific dielectric constant and conductivity σ of the circumferential material of the receiving coil 4. In other words, the specific dielectric constant and conductivity σ of the circumferential material are measured by the voltage V induced across the receiving coil 4. When there is no dielectric material at the circumference, the output voltage V is high. For this purpose, a proper intermediate voltage (v) is set to a voltage comparator 2 to decide on whether the circumferential dielectric material is present or not and to detect the liquid level or surface level.
YOSHIHARA TSUTOMU
SATOU HIDEAKI
ISHIKAWA YUKIHIKO
MAKI MASAMI
EBARA KATSUO
| JPS5133253U | 1976-03-11 |