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The transmit-reflect-receive principle is the basic operating mechanism of radar level gauges. Used for measuring the liquid level in pressure vessels, they have advantages such as immunity to the effects of high temperature, high pressure, scaling, and condensates. Their high accuracy, strong corrosion resistance, capability to operate in vacuum environments, and compact design have led to their widespread use, with them playing an increasingly important role in level measurement. Radar level gauges – what else is there that we don’t know about? There are a variety of techniques and methods for measuring liquid levels, and accordingly, there are various measuring instruments such as magnetic flap level gauges, float level gauges, steel belt level gauges, radar level gauges, magnetostrictive level gauges, radio frequency admittance level gauges, fork-type level gauges, glass plate/glass tube level gauges, hydrostatic level gauges, pressure-based level transmitters, capacitive level gauges, intelligent electric float level gauges, float level transmitters, external measurement level gauges, ultrasonic level gauges, and more. Depending on the medium and site conditions, various level gauges exhibit their respective advantages, resulting in a diversified landscape. Radar level gauges operate on a transmit-reflect-receive principle. The antenna of a radar level gauge emits electromagnetic waves, which are reflected off the surface of the substance being measured before being detected by the antenna again. The time it takes for these electromagnetic waves to travel from emission to reception is proportional to the distance to the liquid surface; the relationship is as follows: D = CT/2, where D is the distance from the radar level gauge to the liquid surface, C is the speed of light, and T is the time it takes for the electromagnetic waves to travel. By recording the time taken by the pulse waves, and since the speed of propagation of the electromagnetic waves is constant, it is possible to calculate the distance from the liquid surface to the radar antenna, thereby determining the liquid level. In practical use, radar level gauges come in two types: frequency-modulated continuous wave and pulse wave types. Level gauges that use frequency-modulated continuous wave technology consume a lot of power, require a four-wire system, and have complex electronic circuits. Level gauges that utilize radar pulse wave technology have low power consumption; they can be powered by 24VDC in a two-wire system, are easy to make intrinsically safe, offer high accuracy, and have a wider range of applications.