Reflection measurement
The reflection measurement determines the amount of energy reflected by the DUT (radome). This energy does not pass through the radome and consequently contributes to performance degradation. Reflected signals decrease the performance of the radar and can even interfere with the received signals, leading to reduced radar sensitivity, less accuracy or even blocking. Areas with high reflection can result from material defects, undesired interaction between several layers of materials, excessive amounts of certain materials, thick paint, foreign objects and other reasons.
The R&S®QAR measures spatially resolved reflection by coherently linking the information collected by the distributed transmit and receive antennas. The resulting millimeterwave image allows for an intuitive evaluation of the material reflection behavior.
The GUI of the QAR software provides a dedicated area for the measured millimeterwave image. The relevant data can be exported for later use in external applications.
Transmission measurement
The total amount of radar energy that passes through the radome is crucial. High losses reduce the maximum range in which a radar can detect a target. For example, if the radome causes a 3 dB two-way transmission loss, the maximum range would be reduced by 16% according to the radar range equation.
In order to determine the transmission loss of the radome, the R&S®QAR can be equipped with an optional transmitter module that is located behind the DUT. This module delivers spectral information regarding the DUT’s RF matching at the exact frequency band intended for radar operation, either 77 GHz or 79 GHz. The spectral measurement is therefore independent of the actual signal waveform utilized by the radar unit, which facilitates testability and optimization of the radome itself and makes it future-proof for new radar generations.
