The use of the radar level transmitter for the process industry started back in 1991. These were large units and operated with a 6GHz frequency. They were generally sold into liquid applications and only considered when no other technology would work. They weighed several kilograms and only operated from an AC supply.
In 1997, Vega released the world’s first true loop-powered radar level transmitter, which gave the company an opportunity to offer a more suitable transmitter for typical process applications. However, they also came with limitations.
Then 1999 saw the 26GHz radar level transmitter being released, offering a smaller unit with a reduced antenna size and narrower beam angle, with the downside to such lower frequencies being 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, an area where, thanks to customer feedback, the parameters for setup were improved making them more descriptive and user friendly.
As with all developments, a point is reached where the components and physics of the technology have been maximised. It was at this stage that Vega started research on the 80GHz frequency range. This frequency was not new to the market and was still 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 of these opened up more opportunities for the use of the radar that has never been practical in the past. For the first time, it also allowed for antenna sizing and adaption to many typical process fittings that exist in industry. One of the things noted in regards to radar frequencies was that as the frequency was increased, the antenna size and the beam angle were reduced.
Radar level transmitters work on the reflection of the signal from the product being measured. The strength of that returned signal was based in the dielectric constant (conductivity). For applications that had a relatively low DK value, radar, in the past, was considered not suitable for the application. The 80GHz allowed these measurements to take place, but there were other considerations.
As well as the high frequency, users also needed quality components that gave good sensitivity, or dynamic range as it was commonly known. Typically, up to this point, radar level transmitters had a dynamic range of around 90db. This 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. So what does this mean for the end user? As with audio, for every increase of 3db you get a doubling of the power. An increase of 30db over previous and existing radar frequencies can achieve an increase of over 1000 times in the sensitivity of the Vega 80GHz radar level transmitters. For this increase, Vega transmitters are able to measure low DK products, such as plastics.
Radar level transmitters, like all instruments, have their limitations. Many limitations are set by the physics of the technology. It is important to take into account not just the frequency, but all the data, when evaluating whether a transmitter is suitable for the application. The Vega 80GHz is said to be a step forward in solving difficult applications. The company has developed a model for liquid applications and a model for solids applications, as users need different algorithms for the types of process medium
Radar level transmitters are an accepted form of non-contact level measurement and the use of these units have increased many times over the past decade. As with all developments, it has not finished yet and Vega will continue to improve the transmitters so that in the near future, the company again breaks the barriers faced previously and open up the opportunities for radar to solve more applications.