Christian Krebs

Monitoring of wound healing by millimetre wave imaging

Millimeterwaves offer the capability to look through dielectric material. Wound healing processes often have to take place under a cover and especially in the case of broken limbs plaster of Paris bandages have to be removed for inspection. Investigations were done to evaluate the possibility of wound monitoring through plasters.

An Imaging System in the Sub Millimeter Area

The millimeter wave frequency range was pushed through test systems for production lines in the last years. Non destructive test systems for quality control need more powerful sensors to detect non-metallic pollutions inside packages. The millimeter wave frequency range up to the lower terahertz frequencies (T-ray imaging) offers the opportunity to look through many packages. Alternative applications are the detection of non metallic and/or under cloth wearied weapons. Other fields of interest for this frequency range are medical applications, especially the detection of skin cancer.

Inspection of Samples using a fast Millimetre Wave Scanner

Millimeterwaves and terahertz sensors can cover a broad field of applications ranging from production control to security scanners. The outstanding features are the transparency of many materials like textiles, paper and plastics in this frequency region, the good contrast of any humid or dense dielectric material and the capability to employ miniaturized RF systems and small antenna apertures or dielectric probes. A stand-alone-millimetre-wave-imager, SAMMY, was developed and built, to demonstrate the outstanding features of this part of the electromagnetic spectrum for material inspection.

Detection of unmanned aerial vehicles (UAV) in urban environments

The detection and tracking of UAV’s is a critical task for public and military security. The main are the low flight height and the small radar cross section (RCS). The problems increase in an urban environment with many high buildings, especially when tall buildings block the line of sight. A new concept of distributed radar sensors was developed to close this gap. To reduce the impact of radar shadows in urban canyons, a surveillance grid of optical and radar sensors is necessary which covers the complete urban environment. The radar sensors build up different security sectors and monitor all access routes for attacking UAVs. Sophisticated cameras which offer night vision capabilities complete the sensor network to reduce the false alarm rate through these regular, declared UAV flights. Cameras allow the integration of a man in the loop which has the final responsibility to define a target as a threat or not. The system supports the operator with a database which based on optical and radar signature of most commercially available UAV’s.

Radarsystem zur Breitenmessung in Warmbandstraßen

Elektromagnetische Strahlung im Bereich von einigen zehn GHz, sogenannte Radarstrahlung, ist im Gegensatz zu Laserlicht unempfindlich auf Dampf und Staub. Messsysteme, die mit Strahlung in diesen Frequenzbereichen arbeiten, eignen sich daher fur den Einsatz bei den rauen Umgebungsbedingungen in Warmbandstrasen und konnen beispielsweise fur die Messung von Breite und Dicke verwendet werden.

High resolution measurements to determine the permittivity in artificial structures

The characterization of materials is one major task for systems which work e.g. in the field of quality or production control. One factor to analyze material volume information is the permittivity. The following paper describes a measurement method to determine and gives an overview about the measurement system. In addition first measurement results will be shown.

Material scanner in the lower THz

The aim of the project is the development of an imaging system for material characterizations. Measurements with real aperture have been conducted at the frequency range between 75 GHz - 220 GHz in amplitude and phase and from 75 GHz - 260 GHz in amplitude. To increase the measurement time a synthetic aperture (SAR) method will be tested. The following paper presents the actually project results.

A submillimeter wave material scanner - applications and prospects

The aim of this project is the development of a measurement system to analyse different materials. Scalar measurements with a real aperture have been conducted at frequencies between 75 GHz and 260 GHz. Different types of objects have been investigated to show the possibilities and limitations of the system.