Modern communication and military system are facing increasing challenges due to electromagnetic interference in the X-band, which drives the demand for compact and efficient shielding solutions. To address this need, this letter presents a low profile single layer band-stop frequency selective surface (FSS) for the same. Using a standard FR-4 substrate, FSS unit cell is designed which consists of four modified circular loops interconnected through a central square loop. The resulting structure achieves a thin profile of 0.4 mm (0.013λ0), making it suitable for space constrained conformal applications. With an electrical size of 0.203λ0 × 0.203λ0 (6.4×6.4 mm2) unit cell and a figure of merit (FoM) of 4.92 (λ0/U), the proposed design provides 59.4% miniaturization compared to conventional half wavelength FSS. Frequency domain simulations demonstrate a wide stopband response with a fractional bandwidth of 54.47 % covering 6.92 GHz-12.10 GHz. Under normal incidence angle at 10.02 GHz for both TE and TM polarization, Shielding Effectiveness (SE) is 39 dB. The structure exhibits excellent angular stability, maintaining SE for AOI’s up to 85° under both polarizations. Conformal analysis reveals that FSS preserves SE up to 39 dB for bending angle up to 20° within the X-band. The design is further validated by experimental measurement conducted on fabricated prototype.
The filament corner radius is often left uncontrolled in cable manufacturing, introducing uncertainty in the shielding effectiveness (SE) of braided cables. This work investigates the influence of the filament corner radius on the SE of braided cables through full-wave transient simulations. A three-stage non-monotonic evolution of SE with increasing normalized corner radius is revealed: a rapid rise up to 0.5, a stable plateau between 0.5 and 4.5, and a gradual degradation beyond 4.5. A trade-off mechanism between corner smoothing and aperture distortion governs the non-monotonic behavior, where moderate rounding suppresses field enhancement while excessive rounding distorts the aperture and enlarges the leakage area. Based on these findings, a design zone between normalized corner radius values of 0.5 and 4.5 is recommended, within which the SE remains stable against manufacturing variations. These results demonstrate that the corner radius must be treated as a design parameter, providing a quantitative basis for electromagnetic pulse cable manufacturing.
Frequency selective surface (FSS)–based absorbers have become an integral solution for electromagnetic interference (EMI) absorption and radar cross-section (RCS) reduction in modern platforms. However, despite extensive research, the transition of such absorbers toward deployable, scalable, and application-ready implementations remains limited. Motivated by these practical considerations, this letter presents a single-layer, polarization-insensitive, wideband FSS absorber realized on a flexible polyethylene terephthalate (PET) substrate using a screen-printing technique. A simple star-shaped unit cell is employed to achieve wideband absorption while maintaining fabrication simplicity and cost-effectiveness. The proposed absorber exhibits an absorptivity of approximately 97% (≈15 dB) across the X- and Ku-bands and beyond. The wideband absorption performance is experimentally validated using a reference metal plate of identical size, demonstrating a reflectivity reduction of 10–15 dB over the X- and Ku-bands. In addition, under a practical operational scenario, single rows of the proposed absorber achieve an antenna RCS reduction of approximately 5 dB, further validating its applicability in realistic deployment conditions. The results confirm the practical viability of the proposed screen-printed FSS absorber for lightweight, flexible, and deployable EMI absorption and RCS reduction applications.
Conventional slotted coplanar waveguide (CPW) spoof surface plasmon polariton (SSPP) structures suffer from significant radiation leakage, posing a major challenge to their practical implementation in compact and highly integrated microwave systems. To suppress this radiation while preserving microwave-band SSPP propagation, a via-connected single-strip CPW SSPP structure is first proposed, which exhibits a lower asymptotic frequency and achieves more than 25 dB radiation reduction relative to the conventional slotted structure near the peak-radiation region. Building upon this, a fan-shaped radial strip loading topology is subsequently developed to further improve the low-radiation performance, representing an approximately 75% size reduction compared to reported SSPP structures. The analysis indicates that this topology provides enhanced field confinement and favorable transmission performance while enabling a more compact footprint. Fabricated prototypes show good agreement between simulated and measured S-parameters, demonstrating low-pass operation up to approximately 2.35 GHz and an insertion loss of about 0.8 dB on an FR-4 substrate, thereby validating the proposed design strategy. These results indicate the potential of the proposed structures as compact low-radiation CPW-SSPP transmission lines for microwave components and interconnects in EMC-sensitive integrated systems.
Apertures in shielding structures significantly influence electromagnetic shielding effectiveness (SE). An array of smaller apertures is commonly used to balance both ventilation and shielding requirements. This paper investigates how the SE of such arrays varies with frequency and with the number of identical apertures. Previous studies have reported conflicting scaling laws for aperture arrays, with SE reductions as number of apertures increases proportional to either 10logN or 20logN in dB scale, where N is the number of apertures. This paper presents an experimental investigation of the frequency-dependent SE behavior of aperture arrays in planar shielding materials. Measurements show that at low frequencies, where the aperture spacing is small compared to the wavelength, the transmitted electric-field magnitude scales approximately as N, resulting in an SE reduction of 20logN, while at higher frequencies the transmitted field scales approximately as √ N(corresponding to SE reduction of 10logN). These results clarify the origin of the differing scaling laws reported in the literature and provide practical insight for the design of shielding structures over wide frequency ranges.
