Guided wave radar level transmitter is also a commonly used liquid level measurement equipment. Its working principle is based on time domain reflectance (TDR) technology. Guided wave radar level gauges send microwave pulses to the measurement medium and then receive the pulse signals reflected back along the probe. The pulse is reflected on the surface of the medium, and the propagation time of the reflected signal is proportional to the liquid level. Guided wave radar level gauge can measure the level of liquid, solid, foam and other media.

Compared with capacitance level gauges, guided wave radar level gauges have lower requirements on dielectric constant, so they are suitable for a wider range of measurement scenarios. Generally speaking, guided wave radar level gauges can measure liquids with a dielectric constant greater than 1.4. This means that guided wave radar level gauges are more suitable than capacitive level gauges for measuring liquids with lower dielectric constants.

However, the specific minimum dielectric constant value still depends on the design and manufacturer of the guided wave radar level gauge. For more accurate information, it is recommended to consult the device manufacturer's technical specifications or contact the manufacturer.