In this dissertation, the EM wave absorber is developed for 94 GHz band which is mostly used as a detecting radar system. Especially, the detecting radar system used for military purpose is to destroy ground-vehicle system such as Tanks. so, it is essential and important to design, fabricate, and develop an EM wave absorber for 94 GHz band. therefore, the final purpose is to develop the EM wave absorber which has absorption ability more than 10 dB in 94 GHz band and thickness within 1.0 mm.
First of all, to consider a development potential, the absorption ability of samples containing difference composition ratio of Carbon, TiO2, and Permalloy with CPE is analyzing in frequency range of 65-110GHz.
It is possible that the samples have a potential to develop an EM wave absorber for 94 GHz band. but while compared the weight of samples, the sample containing composition ratio of 30 wt.% using carbon is decided.
To design an EM wave absorber in 94 GHz band, the material properties, such as complex relative permittivity and permeability, of samples are calculated from the S-parameter using rectangular waveguide and Jig. Absorption abilities of the EM wave absorbers are simulated using 1D FDTD simulation by changing the thickness without changing the composition.
To verify the design results, the EM wave absorber was fabricated based on the FDTD simulated designs. The simulated and measured results agree very well. As a result, the EM wave absorber which has absorption ability 14 dB in 94 GHz band and thickness 0.7 mm is developed.
The dissertation outline of each chapter is as follows Chapter 1 is devoted to a background and a purpose and a process of this dissertation. In chapter 2, theory of millimeter wave EM absorber is introduced briefly. This includes theory of single-layer absorber and multi-layer absorber. and application of EM wave absorber. In chapter 3, manufacturing process of EM wave absorber samples is described. an analysis and decision of absorber samples is presented. In chapter 4, simulation method of EM wave absorber using FDTD is presented. The simulation results of several thickness are presented. In chapter 5, absorption ability of manufactured EM wave absorber is presented. This includes measurement system and a comparison of simulated and measured absorption ability of manufactured EM wave absorber which is fabricated based on the simulated design is presented. Finally, the conclusions were summarized in chapter 6.