A Wideband Transmission Frequency Selective Surface Rasorber

Frequency selective surface (FSS) has extensively been investigated over the past decades. The most famous applications of FSS are used for antennas radome and controlling radar cross section (RCS). FSS radome could reflect the signal out of the band so that the RCS could be reduced by shaping. However, with the development of radar detection technology, the scattering out of the band becomes non-negligible. In order to improve the problem, the FSS rasorber was proposed. It is the combination of the absorber and the radome. In this paper, a wideband transmission FSS rasorber is designed, acting as a stealthy radome to reduce the scattering out of band of the antenna system. The rasorber consists of an absorption layer (LayerA) and a transmission layer (LayerT). The LayerA, which use a resistor-loaded in Jerusalem cross element with non-touching centre, provides stable losses out of band and minimizes losses in the band. The LayerT use as the ground plane of an absorber based on the absorption layer within the total reflection band and providing a transmission window in the band. In order to obtain a wideband transmission, two series chokes are inserted in each leg in the LayerA and the LayerT adopts a second-order resonator. Moreover, the elements are packed densely owing to a skewed grid in the LayerA and the miniaturized non-resonant element in the LayerT. Superdense arrays cause a more stable performance of the rasorber, especially the delay of grating lobes onset. The composite structure is thoroughly analyzed by means of the full-wave numerical simulation. The simulation shows that the –1 dB transmission window is 5.7 ~ 6.7 GHz, and the –10dB reflection band is 2.2 ~ 5.1 GHz. The design would be widely used in broadband antenna system.