This study intends to provide a comprehensive review of the basic concepts, types, applications, and experimental studies of frequency selective rasorber (FSR) presented in the literature. Analyzing the characteristics of FSR became crucial for future adaptability when taking into consideration of immense development in RADAR, military, stealth, and electromagnetic interference applications. The rasorber was initially conceived as a radome for antennas and it was developed expeditiously in recent years. This survey is focused on evaluating the unit cell design (2D, 2.5D, and 3D), equivalent circuit model, polarization characteristics, fractional bandwidth, insertion loss, absorptivity, bandwidth enhancement for absorption, transmission, and their applications based on the FSR. Various techniques like exploiting lumped elements, magnetic materials, lumped components, dual/triple layer structures, varactor diodes, PIN diodes, and distributed elements (slots and stubs) are used to improve the novelty and performance of the FSR that are discussed in the works of literature. At last, these techniques, bandwidth, structures, and performances are compared based on their relative positions to feature the benefits and limitations.

In this paper, we present a linear to circular polarization converter integrated in a concrete structure to eliminate signal transmission problem originated from the concrete buildings in microwave regime. Two polarization converter samples and a control specimen made by traditional concrete are designed and their signal transmission responses are compared experimentally. Axial ratio values which can be calculated by the ratio between the co-polar transmission and cross-polar transmission results of the proposed samples are below 3 dB and highly sufficient for linear to circular polarization conversion activity. The operating frequency for the proposed sample 1 is between 6 and 6.5 GHz with 500 MHz of bandwidth. The proposed sample 2 exhibits dual-band operation covering frequency bands, 4.58–5.13 and 6.0–6.4 GHz with bandwidths of 550 and 400 MHz, respectively. Operating frequencies of the samples are in the WIMAX frequency bands. In addition, the liner to circular polarization converter design integrated to concrete has a huge potential to improve reflection and directivity parameters of many antennas if it is considered as a radome.

In this paper, a wideband ultrathin metasurface absorber is investigated. The proposed absorber comprises a periodic array of a unit cell ring structure. The ring structure and patch inside are tuned to realize the desired frequency bandwidth. The structure has a frequency bandwidth of 7.4 GHz with a center frequency of 15 GHz and fractional bandwidth of 50%. Simulated and measured results show that the absorption at normal incidence is above 90% in the frequency range of 11.3–18.7 GHz. Furthermore, the thickness of the structure is 1.6 mm. The physical mechanism of the metasurface absorber has been analyzed and justified experimentally.

The airborne radomes have to cater superior electromagnetic (EM) performance with bandpass characteristics of stealth application. In this regard, a hybrid A-sandwich radome is proposed in this paper. The proposed radome consists of a novel strongly coupled frequency selective surface (FSS) core sandwiched between two dielectric layers (acts as skin) to form an A-sandwich structure. The dielectric layers are cascaded in such a way that the middle layer has less dielectric parameters than the skin dielectric. The core layer comprises a modified FSS array using strongly coupled FSS layers through a series of metallic vias. This strongly-coupled FSS element will have the advantage of eliminating inter-element interference and improves the EM performance characteristics of the structure. The structure exhibits very good band-pass characteristics (>90%) at a normal impinging angle with sharp roll-off characteristics. To show the efficacy of the proposed structure, the transmission loss has been compared with that of conventional A-sandwich radomes at 0°, 50° incidence angle for both TE and TM polarization. Conformal analysis of the unit cell has been carried out, and sector-wise thickness optimization was performed to analyze the structure for the conformal shaped radome application. Finally, a physical prototype has been fabricated and measured its scattering parameters, radiation characteristics in a fully shielded anechoic chamber. The results are encouraging and prove its suitability for radome application.