The most crucial part of the radar level transmitter is an antenna, which is the “eye” by which the level transmitter “sees” a product level. If we continue with the analogy, “brain”-drawn conclusions greatly depend on the “vision” quality.

ULM series level transmitters use 2 antenna types:

Horn lens antenna
Planar antenna

Horn lens antenna

A horn antenna is the most optimal, in terms of radiolocation, for level measurement. It has, however, a number of shortcomings: it has to be rather long at a required aperture diameter and is sensitive to moisture precipitation on the internal surface. A horn lens antenna is free of these shortcomings.

The horn lens antenna is used in ULM-11 and ULM-11A1 level transmitters. It consists of a horn and a protective focusing lens while being entirely contained in the level-probe body.

Thus, we solve several problems.

First. The lens optimizes the radiation pattern of the level transmitter's probe and allows the antenna arrangement within a small space.

Second. The antenna is entirely housed inside the body of the level transmitter's probe and avoids mandatory installation inside the tank. The antenna is protected against the atmosphere of the inner tank space using a special convex fluoropolymer lens. This makes level-transmitter arrangement on the tank easier and protects the level-transmitter antenna against moisture precipitation and contamination.

Third. An autonomous heating system in the level probe and the antenna arrangement entirely inside the body ensure a temperature on the external surface of the protective lens, in most cases, 1-20 C above the ambient temperature. This almost prevents moisture precipitation on the lens surface.

Planar antenna

The planar antenna is used in the ULM-31A1 level transmitter. This antenna type is a printed circuit board made of special materials by a special method. It has much lower cost (as compared to the horn lens type), and, most importantly, it is very compact and flat. Therefore, it is fully housed inside the level transmitter body and protected against contacts with the environment. Besides, this antenna allowed us to make the ULM-31A1 level transmitter in such a manner that it ends with a flat flange with no parts projecting towards the tank.