VEGA Guided Wave Radar Keeps It Simple

Guided wave radar is the ideal technology to 
measure level in liquids or bulk solids across 
a number of industries in a variety of process 
conditions. These sensors are unaffected by 
changing pressure, temperature, or a product’s 
specific gravity. And unlike other technologies, 
foam, dust, and vapor will not trigger inaccurate 
readings or errors, either. Guided wave radar 
provides accurate, reliable level measurement 
without ongoing maintenance or recalibration. 
And with no moving parts, it’s the ideal solution 
for retrofitting mechanical technology.

How it works
Guided wave radar level measurement comes from time 
domain reflectometry. This technology has allowed people to 
find breaks in underground or in-wall cables for decades. It 
works like this: a low amplitude, high-frequency microwavepulse is sent into a transmission line or cable, and the device 
calculates distance by measuring the time it takes for the pulse 
to reach the break in the line and return.
The same principle applies for a guided wave radar sensor. 
A probe is mounted onto the tank, vessel, or pipe where a 
measurement is needed. A microwave pulse is “guided” 
downward by the probe where a portion of the pulse will be 
reflected by the solid or liquid material being held in the tank. 
The amount of time it takes for the pulse to be transmitted 
and returned determines the level inside the vessel being 
measured. Conductive materials reflect a large proportion 
of the transmitted energy while non-conductive materials 
reflect a small portion. The reflective properties of what’s 
being measured can determine the effectiveness of this type 
of measurement. Since its invention, guided wave radar has 
been used to measure level in industries ranging from food 
and beverage to chemical and refining.

Types of probes

Guided wave radars use a number 
of different probes to make their 
measurements. Each different probe 
has its own purpose and advantages. 
Some are better for making 
measurements in liquids or solids. 
Others work better with lower 
reflectivity materials, thick foam, 
excessive buildup, or corrosive and 
abrasive materials. These probes 
commonly come in customizable 
lengths, so finding the right length for 
differently sized vessels is relatively easy.

Advantages
Setup and configuration for guided wave radars are about as simple as they come. 
VEGA guided wave radars are ready out of the box, configured at the factory for 
the probe’s operating span. Users only need to install the sensor and go through the 
guided setup procedure to begin receiving accurate measurements within 2 mm. 
Guided wave radars need no additional calibration. Other technologies require 
users to empty the tank to show the sensor different levels like 0%, 50%, and 
100%. This can be time consuming and expensive. Lastly, guided wave radar has no 
moving parts. Pressure sensors, floats, and displacers all have mechanical parts that 
can wear out, which means additional maintenance and another calibration. All of 
this means less time and money spent on setup, maintenance, and troubleshooting.
Unlike other sensors, guided wave radar feels right at home in tight spaces like 
pipes, stilling wells, small chambers, and bypass tubes. The very nature of their 
guided signal allows an accurate measurement where other sensors cannot go. These 
sensors can measure in a number of process conditions and still make accurate 
measurements regardless of the environment. This means guided wave radar sensors 
won’t fail with changes in temperature, 
pressure, or specific gravity. These sensors 
are also immune to dust, excessive foam, 
buildup, and noise, making them an ideal 
sensor across a number of industries.
Guided wave radar is also the ideal choice 
for measuring interface simply because 
of how it works. The emitted microwave 
pulses are constantly traveling down and up 
the length of the probe. Most of the energy 
bounces back near the surface of what is 
being measured, and a level is calculated. Since the remaining energy continues to 
flow down the probe and through the liquid, the sensor will receive a second level 
reading, giving the user a measurement of the interface point. All that’s needed is an 
additional calculation for the amount of time it takes for a pulse to travel through 
the different liquids.