| Outdoor phased array antennas usually have a radome to protect the antenna. For large aperture arrays like the SKA Mid Frequency Aperture Array (MFAA) it is important to use cheap materials for the (many) radomes.
The relevant electrical parameters of radome materials are the dielectric constant and the loss tangent. The measurement method uses a ring resonator. The setup is shown in the first picture. The screen on the network analyzer shows a typical measurement. Each peak corresponds with a resonance frequency. These resonance frequencies are directly related to the dielectric constant. The width of each peak is a measure for the losses of the material under test (a wider peak means more losses).
The material under test is shown in the last picture. It is a biobased material that is measured within the framework of the BEETs project. The goal of this project is to investigate the use of biobased materials for high-end applications such as radomes. The partners in this project are Suikerunie, Philips Consumer Lifestyle, Rijksuniversiteit Groningen (RUG), the Aachen Maastricht Institute for Biobased Materials (AMIBM) and ASTRON. The project is funded by Samenwerkingsverband Noord-Nederland (SNN).