Contents I. Introduction
Frequency selective surfaces (FSSs) have been widely used in many applications, such as radomes, antennas, and reflectors, due to their spatial filtering characteristic [1], [2]. In addition, bandpass FSS can be used in radome designs to achieve good transmission. However, strong reflection usually exists at frequencies outside the passband, which increases radar cross section (RCS) greatly. In order to reduce these reflections, a new concept, namely rasorber, has been introduced recently [3]. The frequency-selective rasorber is actually one kind of periodic structure transmitting incident waves in certain frequency band while absorbing in others. Owing to the special performance, a rasorber is very useful in stealth applications to reduce RCS, as well as in electromagnetic compatibility applications to reduce mutual interference.
