A Wideband Amplifying Frequency-Selective Rasorber Based on a 2.5-D Antenna-Circuit-Antenna Structure

This paper proposes a 2.5-D wideband amplifying frequency selective rasorber (AFSR). Firstly, a 2.5-D antenna-circuit-antenna frequency selective surface (FSS) based on the conventional 2-D surface-circuit-surface metasurface design was proposed, which can reduce the design complexity of amplifying frequency selective surface (AFSS). To achieve a wideband passband, a patch antenna with a U-shaped slot serves as both a receiving and transmitting antenna. The power amplifier circuit is connected between the receiving and transmitting antennas to provide power amplification. The power amplifier circuit, transmitting antenna, and receiving antenna makes up the AFSS. To achieve out-of-band absorption, a lossy layer which is composed of metal wires with resistors and rectanglular spiral resonators is layered on top of AFSS. The equivalent circuits for the AFSS and AFSR have been derived. The lower absorption band ranges from 3.1 GHz to 5.1 GHz, while the upper absorption band ranges from 7.3 GHz to 9.6 GHz. The amplifying passband ranges from 5.2 GHz to 7.2 GHz, with a maximum gain of 11.2 dB obtained through experimental results. The proposed AFSR can be used as the antenna's radome to provide power amplification and RCS reduction, improve the detection distance and accuracy and improve communication quality. The experimental and simulation results agree well. To the best of author’s knowledge, this is the first realization of an amplifying rasorber.