A Circuit Analog Absorber With Optimum Thickness and Response in X-Band

A wideband circuit analog absorber in X-band is proposed. The design is discussed by the unit cell and equivalent circuit model. A unit cell of the periodic structure for the absorber is designed and simulated. The absorber consists of two RO 4003 layers separated by air distance. With the thickness of 3 mm, the absorber offers a -20-dB bandwidth of 40%. A novel method for estimating the optimality ratio of planar absorbers is also proposed. The optimality ratio of the designed X-band absorber is calculated with the proposed method, and the result is about 80% optimality in frequency response and total thickness.