Permeable wave absorber

In this paper, a new type of wave absorber permitting transmission is proposed. This absorber has a simple configuration consisting of a resistive film attached to the location where a metal backing is placed in an ordinary absorber. Allowance for transmitted waves and use of a lossless dielectric layer are the unique features. In contrast to the conventional wave absorber, a new degree of freedom is added to the structure and characteristics. By means of equivalent circuit analysis, the reflection and transmission coefficients of the present wave absorber are derived. The nonreflection condition is derived by taking into account the region behind the wave absorber. Based on this derivation, a wave absorber is designed and various characteristics are calculated. The validity of the theoretical results is confirmed by experiment. (C) 2003 Wiley Periodicals, Inc.