RF Sensors

Microwave Antennas & RF-Sensors

General RF Sensors MMW Devices

RF Sensors


The research of the Microwave Sensor Team is focused on permittivity and velocity sensing at micro- & millimeter waves, specialized in mass flow sensors for the detection of conveyed media such as solids/air or liquids/solids, e.g. in pipelines.

Permittivity and permeability detection

The accurate knowledge of complex material parameters allows either the use of novel material design at microwaves or the precise detection of these material parameters using microwave sensors.

Resonator based detection methods are well suited for precise characterization of the complex permeability and permittivity of material samples at single frequencies.

Broadband characterization techniques provide good measurement results in a wide frequency range, using free space, waveguide-based and coaxial transmission line based setups.

Combining both techniques, precise, complex material parameters can be extracted over a wide frequency range at micro- & mm-waves.

Velocity detection

The detection of the particulates velocity of grain material and powders is a research topic focused on sensor systems, that provide the following characteristics: high precision, non-contact, integral measurements over a time period and correlation techniques.

The long-term goal is a high-precision mass-flow detector with moderate costs, including both, the permittivity and the velocity sensors.


Particulate mass flow meter have been developed using resonant cylindrical waveguide resonators that avoid disturbances of the material flow in the pipeline. The waveguide resonators consist of

  • Microstrip Patch Sensors
  • Composite Right/Lefthanded Transmission Line structures

A new extraction algorithm has been introduced to detect the material concentration and the velocity of particulate solids out of a single time continuous measurement. The autocorrelation function and the pre-knowledge of the time dependent phase shift, when particles fly through the sensor, are used for precise particle velocimetry.