In this article, a wideband energy selective surface (ESS) with quasi-elliptic response and high shielding effectiveness is proposed for providing out-of-band rejection and high-power microwave protection at the same time for wideband systems. By cascading three layers of structures and loading diodes, wideband quasi-elliptic response and nonlinear transmission property are realized. The ESS has a wide pass-band and high out-of-band rejection simultaneously with turned off diodes under a low-power incidence. On the contrary, under a high-power incident wave, diodes are turned on adaptively, leading to a high shielding in wideband. An equivalent circuit model is first designed in which a three-order Chebyshev filter with a serial LC and diodes is schemed. ESS structure is then constructed based on the circuit model. Field-circuit cosimulation is employed to analyze the power-dependent transmission property. In addition, two prototypes are designed and measured in rectangular waveguides, where it can be seen that the simulation and measurement findings agree well. The proposed ESS has a wide pass-band of 6–10 GHz and great out-of-band rejection with one transmission zero at 11.6 GHz under a low-power incidence, whereas high shielding in wideband is observed for high-power incidence.

Metal mesh films have been shown to be a promising strategy to effectively mitigate the growing issue of electromagnetic interference (EMI) in optoelectronic systems. To achieve superior shielding effectiveness, it is common to increase the thickness of the mesh film. However, mesh-based shielding materials have frequency-dependent shielding effectiveness that decreases as the frequency increases. Simply increasing the thickness of the mesh cannot effectively enhance the EMI shielding effectiveness at high frequencies. This will further lead to challenges such as increased processing difficulties and higher costs. In this paper, we present an infrared transparent electromagnetic shielding window based on metal mesh with irregular patterns and proper thickness. The mesh coating is fabricated on a sapphire substrate using ultraviolet photolithography technology and exhibits an efficient electromagnetic shielding effectiveness of more than 20 dB over the wide frequency range of 1.7–18 GHz while maintaining high infrared optical transparency. More importantly, there is no distinct variation in shielding effectiveness between low and high frequency ranges, demonstrating a balanced shielding characteristic across a broad frequency band. This work could be crucial in designing cost-effective and efficient EMI shielding windows for optoelectronic systems.

In this paper, a flexible and frequency-reconfigurable band-stop Frequency Selective Surface (FSS) is studied theoretically and experimentally. The flexible FSS is fabricated through screen printing, a low-cost, high-efficiency additive manufacturing methodology. With the load of bias voltage controllable varactor, resonance frequency tuning from 3.51GHz to 6.02 GHz has been measured to prove the frequency reconfigurability of the FSS under bias of 0-20V. Outstanding wide angular stability under oblique incidence has also been examined both in theory and measurement. The FSS resonance frequency is completely fixed under incidence from 0°-60°, and the angular stability maintains under different bias voltages. The mechanical flexibility, frequency-reconfigurability and angular stability makes it meaningful in applications of flexible/conformal coverage for aiming objects, including electromagnetic scattering control, EMC (Electromagnetic Compatibility), etc.

Flexible metamaterial absorber manufactured with layer-by-layer screen overprinting methodology has been theoretically and experimentally studied in this wok. The effective absorption of the absorber is in X band (8.3GHz to 10.9GHz) and its working principle have been verified and analyzed. Benefiting from the elimination of the parasitic effect brought by package-free and direct-contacted planar resistors, high agreement between simulations and measurements has been achieved. The working frequency band can be easily tuned by replacing different supporting and covering layers, to fit various purposes. Mechanical flexibility of the absorber enables its conformal coverage to aiming objects for RCS reduction, and is experimentally confirmed on metallic cylinders with different diameters. It has been clearly demonstrated that the high-efficiency and cost-effective automatic screen-overprinting method matches perfectly for large-size flexible absorber and its industrial applications.

A comprehensive summary on the recent progress of Ag NWs from synthesis, growth mechanism, device fabrications to prospective Engineered Applications.