Optimal Design Of Wideband Radar Absorber Based On Periodic Resistance Surface

The rapid development of electromagnetic detection technology lead to an increasing demands for stealth material, they are required to be wideband and have deep absorption with much thinner thickness and lighter weight, however, the conventional electromagnetic materials cannot meet all these requirements. A variety of modified electromagnetic stealth materials with composite structures became a hot spot in international research. Improved designs based on the existing design experiences, which can bring more benefit and begin to apply to the fields of national defense and civil technology.This dissertation focuses on the work of improving multilayered structure of the classic Jauman absorber. Traditional Juaman Absorber which can broaden its bandwidth by increasing the number of unit structure in cost of the total thickness.By replacing conducting surface with the resistive one in the Frequency Selective Surface (FSS) in Jauman Absorber, and optimizing the parameters of the absorber by employing the genetic algorithm (GA), we broaden the bandwidth of the absorber and effectively reduced its total thickness. The main contributions of the dissertation include:1. As a classic structural absorbing material, Jauman absorber has an important theoretical value in the design of electromagnetic stealth material. Analyze and design of the traditional Jauman absorber, forms the theoretical basis of this dissertation.2. Genetic algorithms have been used to optimize all the parameters in the design. As a global algorithm the genetic algorithm has many advantages, it can find the solution of the optimize problem efficiently and accurately.3. Periodic resistance surface is employed to act the same role as the resistance screen in the Jauman absorber, and its analysis is very important in our work. Unit cell of the periodic resistance surface made up by square patch array is discussed and the corresponding equivalent circuit parameters are exhibit in the paper and verified by full wave simulation. By using the capacitance characteristics of square patch, we design an absorber of only two layers which has good performance within4～20GHz band with reflection coefficient under-10dB. The thickness of the absorber is very close to its theoretical limit. Finally, we have verified the designs by employing the full wave electromagnetic simulation.4. Consider the capacitance and inductance characteristics of a periodic resistance surface with square ring structure, a single layered structure is proposed and analyzed in the dissertation. which has a bandwidth of5～17GHz with the reflection coefficient below～10dB, and the total thickness is only5mm. Full wave electromagnetic simulations are used to verify the design results.