Ultrathin 3-D Frequency Selective Rasorber With Wide Absorption Bands

Dual‐polarized frequency selective rasorber with dual absorption bands

“…Despite the fact that the 3‐D FSS structures are relatively complex to fabricate, several the design calls for salutary features such as high selectivity, low‐insertion loss, broadband performance, and low profile of the unit cell render the choice of 3‐D AFST an attractive one for several applications. A number of designs for the 3‐D FSSs are available in the literature 15–18 . In Reference 15, a 3‐D FSR has been proposed with only a single absorption band and furthermore, it is expensive to fabricate because the design calls for a large number of lumped elements.…”

“…The AFST described in Reference 16, which has no lumped components, does have a wide absorption bandwidth, which is desirable; however, this design is difficult to realize in practice owing to its complexity. The 3‐D FSR, described in Reference 17, has a remarkably thin profile and relatively wide absorption bands, all of which are desirable features. However, all the above structures suffer from the limitation that they can only handle a single polarization.…”

Novel Frequency-Selective Rasorber with Ultrawide Absorption Bandwidth Covering Both the X- and Ku-Bands

“…However, the FSS can only deal with mono-static Radar Cross Section (RCS) reduction, and arbitrary reflected out-of-band signals will lead to an increase of bistatic RCS [7][8][9]. To solve this imperfection, a so-called frequency-selective rasorber (FSR) was proposed [10] and has already attracted much attention [11][12][13][14][15][16][17][18][19][20][21][22][23]. The operation mechanism of an FSR is a combination of traditional FSS and a metamaterial absorber; it thus absorbs the out-of-band waves instead of reflecting them to reduce the bistatic RCS.…”

“…An ideal FSR should have zero insertion loss (IL) for operating in-band electromagnetic (EM) signals while having 100% absorptivity for out-of-band signals [11][12][13][14]. To achieve these goals, both 2D-FSR and 3D-FSR have been developed in previously published studies [11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26]. The 2D-FSR maintains the multilayer structural form similar to FSS, and it usually consists of a lossy resistive sheet and a lossless FSS layer [14,15].…”

“…The lossy layer performs as an absorber for out-of-band signals while the lossless layer stops the undesired signal and allows the in-band signal to transmit freely. The unit cell of a 3D-FSR is usually constructed from several pairs of parallel-plate PCB boards to form multimode cavities [15][16][17][18]. These cavities contain a lossy mode and a lossless mode for different frequency band EM waves.…”