80GHz radar transmitters
THE use of the radar level transmitter for the process industry started back in 1991.
These were extremely large units and operated with a 6GHz frequency.
The units were sold generally into liquid applications and were only ever considered when no other technology would work.
They were a large unit weighing in at several kilograms and operated only from an AC supply.
In 1997, VEGA released the world’s first true loop-powered radar level transmitter, offering a more suitable transmitter for typical process applications, but once again they came with their limitations.
1999 saw the release of the 26GHz radar level transmitter that offered a smaller unit with a reduced antenna size and narrower beam angle (a downside to lower frequencies is the larger beam angle).
VEGA continued to develop and improve radar level transmitter performances through the first decade of the 2000s.
The main changes were in the software area, where thanks to customer feedback, the parameters for setup were improved and much more descriptive and user-friendly.
As with all developments, there comes a point where the components and physics of the technology have been maximized.
At this stage, VEGA started research on the 80GHz frequency range.
This frequency was not new to the market as it was and still is quite common in the automotive industry with reversing sensors.
During the research and development of this frequency, VEGA carried out a number of real life customer trials and the results opened up many more opportunities for the use of the radar that have never been practical before.
It also allowed antenna sizing for the first time and for adaption to many typical process fitting that exist in industry.
One of the things to note in regards to radar frequencies is that as the frequency is increased, the antenna size and the beam angle reduce.
Radar level transmitters work on the reflection of the signal from the product being measured and the strength of that returned signal is based in the dielectric constant (conductivity).
So applications that had a relatively low DK value radar were considered to be not suitable.
80GHz units now allowed these measurements to take place, but of course there are other considerations.
As well as the high frequency, quality components were needed to give very good sensitivity or dynamic range as it is commonly known.
Typically up to this point, radar level transmitters had a dynamic range of around 90db – that was until the VEGAPULS 64 (liquids) and the VEGAPULS 69 (solids) were developed.
VEGA now manufactures a radar level transmitter with a dynamic range of 120db.
This means that, as well as with audio, for every increase of 3db, there is a doubling of the power.
An increase of 30db over previous and existing radar frequencies meant an increase of over 1000 times is achieved in the sensitivity of the VEGA 80GHz radar level transmitters.
For this increase, VEGA transmitters were now able to measure extremely low DK products such as plastics.
Radar level transmitters, like all instruments, do have their limitations, many of which are set by the physics of the technology.
It is very important to take into account not just the frequency but all the data when evaluating whether a transmitter is suitable for the application.
For VEGA, the use of 80GHz has proven to be a large step forward in solving difficult applications, but the company has also developed a model for liquids and solids, as different algorithms are needed for the types of process medium.
Radar level transmitters are now a very accepted form of non-contact level measurement and the use of these units have increased by many times over the past decade, but as with all developments it has not finished yet.
VEGA will continue to improve the transmitters to continue breaking barriers faced previously and open up the opportunities for radar to solve more and more applications.