RF & MW Characterization of Advanced Materials with High Accuracy for Space Applications

Abstract

Electromagnetic characterization is a fundamental piece when designing systems that will be present in space missions. These systems must function correctly immersed into the electromagnetic environment they are going to find, preventing electromagnetic interference (EMI) from affecting their characteristics and properties [1]. In addition to the study of the system itself, it is equally important to know the behaviour of the materials with which these systems will be built in the presence of electromagnetic radiation, so that their viability can be established [2] [3]. On the other hand, taking into account the communications in space, the characterization of antennas is essential during their design phase. All these points are taken into account in the development of the project Large European Antenna (LEA) [4] [5], which is focused on how to build powerful antennas for specific Earth observation, telecommunications, etc., that can automatically self-deploy in space. This type of antennas is commonly formed by complex knitted meshes of gold-plated metals [6] [7] [8]. For these structures there are two important issues regarding radiofrequency (RF) characterization which are its reflectance and transmittance properties. In this case, it is important to ensure that the RF behaviour of the mesh surface is well enough to guarantee that the final reflector accomplishes the RF specifications of the antenna. The following communication will present two test benches (POLYBENCH and mmW-BENCH) that allow to electromagnetically characterize materials with high accuracy from 2.6 GHz to 110 GHz; both test benches fully designed and developed by the National Institute of Aerospace Technology (INTA) and both are based in the free space method, which allows measurements in a wide range of frequencies with great precision and with relative simplicity and speed [9]. The tests carried out focus on the measurement of the reflection and transmission coefficients of different test samples, in two orthogonal polarizations and on different points of each sample, with an accuracy below ± 0.1dB in amplitude. This paper is structured as follows: first an explanation of the test benches used to carry out the measurements is provided; then, the procedure of the measurements is explained; after that, an analysis of the measurement errors is given and finally some conclusions are presented.