Abstract:In this research article, the superformula is used to design the geometry of a frequency selective surface (FSS) unit cell, which resembles the shapes found in nature. The designed shape of unit cell is like petals, which may take different form by varying the values of six parameters. The proposed FSS unit cell has both angular and polarization stabilities of incident wave. For the miniaturization of FSS and decrease of resonance frequency, interdigital capacitances (IDCs) are devised in the FSS structure, wh… Show more
“…To accommodate the frequency response of the MT-ATFSS, the lossless layer is required to emerge transmission/reflection selective characteristics on the basis of a two-port network [26,27]. The proposed lossless layer is cascaded by the composite structure of cross and square rings, which can be equivalent to multiple LC series branches in parallel connection.…”
An absorptive/transmissive frequency selective surface (ATFSS) with multiple transmission zeros is proposed, which consists of one lossy layer and two lossless layers separated by air space. As the key features, the slot-line loading and electromagnetic coupling technologies are adopted in the lossy layer and lossless layers, respectively, to introduce the infinite impedance points and four transmission zeros, thereby simultaneously achieving low insertion loss and high selectivity of the transmission band. Benefiting from the ohmic loss of the lumped resistance in the lossy layer, effective absorption can be readily implemented. A detailed qualitative analysis of the proposed structure is presented through the equivalent circuit theory, surface current, and power loss density distributions. Under normal incidence, the overall structure exhibits two discrete absorption bands over the frequency range of 6.34 to 13.40 GHz, whereas a transmission behavior is obtained from 9.34 to 11.40 GHz with a minimum insertion loss of only 0.14 dB. In particular, there are only 3.9% and 3% transition bandwidths between absorption and transmission functions. Then, a sample prototype is fabricated for demonstration, and the measured results are well consistent with the simulated one. As expected, the proposed ATFSS has the advantage of multiple transmission zeros, loss insertion loss, and narrow transition band, which is of great potential in the application of radar stealth radome.
“…To accommodate the frequency response of the MT-ATFSS, the lossless layer is required to emerge transmission/reflection selective characteristics on the basis of a two-port network [26,27]. The proposed lossless layer is cascaded by the composite structure of cross and square rings, which can be equivalent to multiple LC series branches in parallel connection.…”
An absorptive/transmissive frequency selective surface (ATFSS) with multiple transmission zeros is proposed, which consists of one lossy layer and two lossless layers separated by air space. As the key features, the slot-line loading and electromagnetic coupling technologies are adopted in the lossy layer and lossless layers, respectively, to introduce the infinite impedance points and four transmission zeros, thereby simultaneously achieving low insertion loss and high selectivity of the transmission band. Benefiting from the ohmic loss of the lumped resistance in the lossy layer, effective absorption can be readily implemented. A detailed qualitative analysis of the proposed structure is presented through the equivalent circuit theory, surface current, and power loss density distributions. Under normal incidence, the overall structure exhibits two discrete absorption bands over the frequency range of 6.34 to 13.40 GHz, whereas a transmission behavior is obtained from 9.34 to 11.40 GHz with a minimum insertion loss of only 0.14 dB. In particular, there are only 3.9% and 3% transition bandwidths between absorption and transmission functions. Then, a sample prototype is fabricated for demonstration, and the measured results are well consistent with the simulated one. As expected, the proposed ATFSS has the advantage of multiple transmission zeros, loss insertion loss, and narrow transition band, which is of great potential in the application of radar stealth radome.
“…The split maze is proposed to get resonance at different frequencies in X (8-12 GHz) and Ku (12-18 GHz) bands in 17 . The use of super-formula to propose the frequency-selective surface to have narrow-band resonance at 3.5 GHz is shown in 18 . All the above-proposed designs are narrow-band and thus have lower practical utility.…”
In this paper, the authors, for the first time, have shown the use of 2D conformal microwave absorbing material (MAM) in the design and fabrication of a portable Anechoic chamber (AC). The MAM is fabricated on the transparent and conductive metal oxide layer named indium-tin-oxide (ITO) with Polyethylene terephthalate as the substrate and the ground plane for zero transmission having overall thickness of 0.012$$\lambda$$
λ
where $$\lambda$$
λ
is calculated at 0.7 GHz. The MAM is characterized for 0.7 to 18 GHz for both TE- and TM-polarisation and oblique incidence. High sheet resistance, dipole-like resonance structure patterned on the ITO, and the air-spacing between the layers is optimized to achieve broadband absorption. The MAM is used to line the six sides of the rectangular anechoic chamber having inner dimensions of: (L × W × H: 850 × 650 × 720 mm3). The return loss (RL), gain, and radiation pattern of three antenna working at 1.56, 2.43, and 4.93 GHz are analyzed inside the AC. The measurement results for all frequencies very well match with the simulation studies, thus validating and opening the door for the future use of ultra-thin and planar MAM in the AC.
“…Also, the designer can use equivalent circuit to reduce the design efforts and simulation tasks for a particular structure with the desired specifications. The equivalent circuits actually provide some primary design guidelines 25 , 26 . Figure 7 ( a ) Surface current.…”
In this research article, A miniaturized hexagonal split-ring 2.5-dimensional (2.5-D) unit cell is proposed for frequency selective surface (FSS) applications. The 2.5-D FSS provides efficient usage of the available surfaces and optimum increased current paths by connecting its two sides through vias. The size of the FSS unit cell is $$0.026{{\varvec{\uplambda}}}_{0}\times 0.026{{\varvec{\uplambda}}}_{0}$$
0.026
λ
0
×
0.026
λ
0
at the resonance frequency of 1.25 GHz. The proposed FSS has good angle stability due to its small size. The effects of variation of FSS geometry parameters on transmission zero are investigated, namely, the control of bandwidth and roll-off of frequency response by these parameters is studied. An equivalent circuit is obtained for the proposed structure to predict its frequency response, which agrees very well with the results of full-wave simulations. A prototype model of the proposed FSS structure is designed, simulated, fabricated, and tested as proof of concept.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
