Why is adequate testing of radomes so important?
In the industry there is a rapidly growing awareness of the importance of radome tests. They ensure that radomes and their covering do not impair the functionality of radars. That's because the more intensively we use technologies for autonomous vehicles, the more important it is to correctly perceive the environment – especially with regard to safety. It's the same as with our eyesight: a radar, like a pair of eyeglasses, allows us to see certain things. The quality of the radome determines how clean the glasses are and how clearly and homogeneously we can perceive our environment.
What is the operating principle of the Rohde & Schwarz test solution for checking the quality of radomes?
The R&S®QAR can generate spatially resolved millimeterwave images of radar reflections and the degree of transmission of a radome to visualize inhomogeneities in the material. Measurements with the R&S®QAR take just a few seconds and are very precise. Unlike customary production measurement methods, the measurement is independent of a golden radar device, and requires significantly less space than a conventional setup with several angle reflectors.
Going back to the analogy with eyeglasses: they should be equally transparent everywhere. The objective of the R&S®QAR is to ensure this. If this homogeneity is not achieved, there will be distortions and the radar will detect things in places where nothing is there. As a result, downstream functions may be falsely triggered, for example causing emergency braking of a vehicle unnecessarily. The R&S®QAR enables manufacturers to avoid situations like this.
What do the results look like?
The results from our radome test are divided into data about reflectivity and data about transmission. The reflectivity is spatially resolved, which is the unique capability of the R&S®QAR. It allows us to easily see where there is something wrong with the radome. We may not be able to say directly what the cause is, but in most cases the radome manufacturer can help with this – for example, when there are problems with delimitation here during production.
Already during production, the R&S®QAR can ensure that all radars are properly mounted, calibrated and in good working order. We have also expanded the instrument's imaging functionality so that we can evaluate a vehicle's CAD data that we obtain from the manufacturer. This means we take a picture with the R&S®QAR – that is our actual data – and compare it with the nominal data from the CAD drawings. Then we can see if the radar is mounted in the right place or something is damaged. This can be used in production the same way as at a car repair workshop.
The technology of the R&S®QAR is based on the technology of the R&S®QPS security scanner. What are the differences?
Obviously, the application area of a security scanner is completely different. Its technology is based on a neural network that looks for unknown and possibly dangerous objects, such as weapons, explosives, etc., in the scanned image of an unknown person with unknown clothing. In contrast, the objective of the R&S®QAR is to make a qualitative assessment of reflection and homogeneity. This means the challenges with radome tests are different, but of course we benefit enormously from the experience we have acquired with the security scanner.
The R&S®QAR is being deployed in many areas of autonomous driving. How do you estimate the future of the market?
Initially this technology will be expensive and more relevant to the logistics sector or mobility service providers. We will have to wait a while and make further refinements before autonomous driving becomes established in the private sector. And that's what we're doing: the more autonomous driving is used, the more sensors will be needed – which means more radars and radomes. Ten to fifteen radars are installed in a highly automated vehicle, mostly hidden behind radomes, bumpers, and front or rear aprons. All these devices and coverings must be tested in production.
What else needs to be tested to arrive at a perfectly functioning radar?
We support every step in the radar development process. From radar chip development to the interference immunity characteristics of the radar to the radome, we have a variety of test solutions available: the R&S®FSW (spectrum analyzer) or the R&S®RTP (oscilloscope) and signal generators. For example, we recently launched an innovative test chamber for indirect far-field measurements, for testing automotive radar sensors. In the end, when all eventualities have been tested and the resulting best possible radar has been installed behind a bumper, this naturally has to be tested as well. For all of this, we have in every case the perfect measurement method.
