Fraunhofer Institute for Industrial Mathematics ITWM
Fraunhofer Institute for Industrial Mathematics ITWM
Hinter der Flugzeugnase aus Verbundwerkstoff - dem Radom - verbirgt sich das Radargerät.
© istockphoto / Flightlevel80
Hinter der Flugzeugnase aus Verbundwerkstoff - dem Radom - verbirgt sich das Radargerät. Ein von uns entwickeltes Millimeterwellen-Terahertzsystem prüft bei der Firma MEGGITT jeden einzelnen Radom in der Fertigung auf Defektfreiheit.

Radome Inspection with THz

Behind the aircraft nose made of composite material – the radome – is the radar unit. A Millimeter-wave Terahertz System developed by our institute checks every single radome in the MEGGITT company for defects.

© istockphoto / Flightlevel80

RADOM – Quality Control in the Aerospace Industry

Imaging testing with terahertz waves is ideally suited for the non-destructive inspection of fiberglass-reinforced composite materials. Such structures are used, for example, for radar domes (radomes) of aircraft, among other things to protect the sensitive radar technology. Terahertz technology enables non-contact inspection of the structure's properties in the field or directly during manufacture.

 

Requirements for the Radome

Radar domes must withstand harsh weather conditions and impacts. They are routinely inspected in the field, but already during production their structural integrity and transmission properties for radio signals must be optimized. Previously used testing techniques such as ultrasonic methods and knock tests can only be used for this purpose to a limited extent and possibly only under special conditions.

Testing with terahertz waves allows non-contact and non-destructive examination of the external and internal structure of composite materials at each manufacturing step or even in the field. Furthermore, we use image processing methods for the automatic detection of defects or other features.

Sensor unit in the tool holder of the production machine
© Fraunhofer ITWM
Sensor unit in the tool holder of the production machine

Spiral Scanning of the Radome

For the British company Meggitt Polymers & Composites, we have developed an industrial 3D terahertz imaging system for the inspection of radome. The simple integration of the measuring unit into the company's production line enables spiral scanning of the entire radome, which can be up to two meters long.

Depending on the type of radome, the thickness and composition of the structure vary greatly. This has a significant influence on the penetration depth of the terahertz measurement signal. When choosing the sensor technology, companies often make a compromise between image resolution and penetration depth. To ensure that both structures several centimeters thick and thinner structures can be examined with the best possible resolution, we have integrated two different terahertz sensors with adjacent frequency ranges into one measurement system. For improved depth resolution, the measurement data from the two sensors can be combined.

The structure of the radome consists of different layers of different materials (e. g. aramid and foam structures).
© Fraunhofer ITWM
Verschiedene Lagen unterschiedlicher Materialien (z.B. Aramid und Schaumstoffstrukturen) eines Radoms
Terahertz measuring unit with connected data connection and power supply
© Fraunhofer ITWM
Terahertz measuring unit with connected data connection and power supply
Reconstructed image of the radome at 100 GHz showing the back of the ­radome.
© Fraunhofer ITWM
Rekonstruierte Aufnahme der Rückseite eines Radoms bei 100 GHz

Related Links: