Analysis of Pyramidal Microwave Absorbers for Enhanced Performance in 1-10 GHz Frequency Range

One of the main applications of microwave absorbers is in anechoic chambers, where the walls are lined with pyramidal foam impregnated with a lossy material. This paper investigates the impact that various design parameters of pyramidal microwave absorbers exert on their performance, with the aim of finding the best design values that ensure better operational properties. Typical pyramid absorbers were investigated by conducting simulations with the use of the CST Microwave Suite simulator, across the frequency range of 1-10 GHz, at various angles of the incident wave. The investigations also considered absorbers backed by conducting plates that are used in shielded anechoic chambers. The study shows that higher permittivity leads to higher reflection, while increased loss tangent improves absorption, and the same applies to magnetic materials. Larger pyramid heights lead to lower reflection, but only in the case of thicker absorbers. A pyramidal absorber with the height of 16 cm, designed using lossy material with permittivity and permeability of 1.5 and loss tangent of 0.5 achieved a reflection coefficient that was lower than -60 dB for frequencies between 3 and 10 GHz. The results are useful in designing absorbers relying on materials that offer only dielectric or magnetic properties, or that combine both of them to achieve enhanced performance.