Design, Numerical Analysis and Test of HF Absorber

Abstract

Listen

Translate article

The paper presents numerical analysis of the microwave absorber design. It is possible to use modifled concept of the absorber. There were used novel numerical methods (flnite element method (FEM)) for thin layers modelling with sandwich non-isotropic electromagnetic materials. Modifled absorber has appropriate properties and it is possible to use it in non- re∞ecting chamber construction. The non-re∞ecting chamber will be used for open space testing of relativistic microwave pulse generator; Pmax = 500MW, tp = 10i100ns. An experimental testing of the proposed pyramidal absorbers was done in the laboratories at University of Defence Brno, Czech Republic. DOI: 10.2529/PIERS060901094301 Figure 2: The shielded laboratory. The calorimetric sensor has disc design. The carbon with changed crystal lattice is used as one of the thin layers. Combined calorimetric sensors was designed for microwave vircator with output power Pmax = 500MW, length of pulse tp 2 ns. Usually, two types of the absorber materials (non-re∞ecting) are used. The polyurethane foam impregnated by graphite is used in high frequency range (more than 1GHz) | the foam employs heat losses in material. The ferrite absorber is used in low frequency range | the ferrite absorber employs magnetic losses. The mentioned materials are used to prevent re∞ection of the electromag- netic waves inside the laboratory. The idea is to rebuild the laboratory in Fig. 2 to the shielded non-re∞ecting chamber for measurements and experiments with power microwave pulse generators iPmax = 500MW, length of pulse tp 2 ns. 2. SHIELDING OF THE WALLS It is possible to deflne an electromagnetic shielding by help of shielding coe-cient ?. It represents the ratio of the electrical fleld Et (magnetic fleld Ht) in the given place of the chamber to the electrical fleld Ei (magnetic fleld Hi) incoming at the absorber. ? = Et