Characterization of Magnetically Loaded Microwave Absorbers

Abstract

Abstract-This work presents new method, retrieved results and validation for complex and frequency dependent permittivity and permeability parameter extraction of two composite, homogeneous and isotropic magnetically loaded microwave absorbers. Permittivities and permeabilities are extracted from free space transmission measurements for frequencies from 22 up to 140 GHz. For validation of the results reflection measurements (samples with and without metal backing) are performed and are compared with simulations that use extracted models. The proposed new method solves some shortcomings of the popular methods: extracts both permittivity and permeability only from transmission parameter measurements, gives good results even with noisy data, does not need initial guesses of unknown model parameters.

Alginate Beads and Epoxy Resin Composites as Candidates for Microwave Absorbers

“…In this way, unknown parameters of Debye model for frequency dependent permittivity are extracted. Procedure for fitting and permittivity extraction is described in more details in [9]. In Figure 5, real and imaginary frequency dependent permittivity of synthesized composites are presented.…”

“…Permittivity values for both epoxies are extracted from transmission measurements in 70 to 110 GHz range. The detailed procedure is described in [9]. As another difference, W19 is less viscous than s2850.…”

“…We will extract effective permittivity of the composites (s2850 and alginate, W19 and alginate and W19, alginate and CIP) in W band as follows. We assume that in the microwave region, synthesized composites have one relaxation frequency and for that reason the frequency dependent permittivity of the composite is represented with Debye relaxation model [9]. This model is incorporated into Fresnell equations based algorithm.…”

“…Simulated reflections of the fabricated samples as well as of commercially available absorbers from CR Eccosorb group (CR114 and CRS117) are presented in Figures 6 to 10. The values for the frequency dependent permittivity of CR114 and CRS117 are taken from [9].…”

Development of Pyramidal Microwave Absorber Using Sugar Cane Bagasse (Scb)

“…Many shapes have been used in the design of the absorbers, including pyramidal [27], wedge shapes [28]; oblique, hexagonal shapes [29]; twisted, convoluted, flat shapes [30]; and multilayer flat shapes [31]. Figure 1 shows a flowchart of the steps followed in an SCB pyramidal microwave absorber.…”