A novel ultrawideband energy selective surface (ESS) in S-band is presented for adaptive high-power microwave (HPM) protection. Periodic metallic textures are designed and loaded with PIN diodes to obtain the nonlinear response that is dependent on the power intensity of incident wave. After the equivalent circuit analysis and full wave simulation, a prototype is fabricated and experiments are conducted under different power levels, which has a good coincident. The insertion loss is less than 1 dB for low-power signals in operating band, while the shielding effectiveness is more than 20 dB when exposed to HPM. Both the measurement results of frequency and time domain have verified the nonlinear transmission characteristics, which demonstrated the HPM protection abilities of the proposed ESS.

This paper presents an Energy Selective Surface (ESS) for high-power microwave (HPM) protection in waveguide, which has a nonlinear transmission response and can adaptively react to the power intensity of incident wave. A prototype of four unit cells loaded with pin diodes is designed and fabricated in L-band. The nonlinear and adaptive transmission characteristics are demonstrated by the waveguide measurements both in time domain and frequency domain. On condition of signal power below 35 dBm, the wave in interested band can propagate through waveguide with a low insertion loss down to 1 dB; while on condition of signal power above 47 dBm, high power would render the ESS into a High Impedance Surface (HIS), and the incident wave would be reflected and dissipated with a transmission coefficient of less than -10 dB, thereby providing the HPM protection ability. Furthermore, the subsequent simulations illustrate that the inserted ESS will not worsen the radiation patterns of the following horn antenna and the induced high-order modes in waveguide keep negligible values below -65 dB.

A novel design method for ultra-broadband energy selective surface (ESS) is presented in this paper based on the equivalent theory from filter circuits to metamaterial units. This method provides a new way of designing ESS in ultra-broadband with low insertion loss and high shielding efficiency from the perspective of filter circuit topology. It is illustrated and verified with a three layer ultra-broadband ESS. Firstly, a third-order filter with a switching bandpass to bandstop in C to Ku band is designed and optimized. Then, the filter is mapped to a physical model of a three-layer ESS which has a nonlinear transmission response for low-intensity radiation field (LIRF) and high-intensity radiation field (HIRF) in C/X/Ku-band. The three ESS prototypes are fabricated and measured in three different band waveguides to prove the design method of the ESS proposed in ultra-broadband. Simulated and measured results demonstrate that low insertion loss and high shielding efficiency at the same time can be obtained under low and high incident power levels, respectively, where the 1 dB loss and 23 dB shielding bandwidth cover from 5.4 GHz to 14.45 GHz. Furthermore, the insertion loss is less than 0.5 dB in the frequency band of 5.45 GHz to 13.8 GHz and maximum shielding effectiveness reaches 25 dB at 10 GHz.

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.

In this article, a PIN-diode-based high-intensity radiation fields (HIRF) protection method was proposed and the sensitivity to the field intensity of incident wave has been verified by a printed dipole antenna loaded with three pairs of PIN diodes at S-band. To illustrate this method, an equivalent linear circuit was raised to analyze the basic operation principle of the proposed antenna. With a low-power incident wave, the PIN diodes are in off-state and the gain of the proposed antenna remains unaffected; while it drops considerably as the PIN diodes are triggered by HIRF. Furthermore, extensive parametric studies of the structure were analyzed by full-wave simulation to investigate the key factors affecting the performance of HIRF protection and antenna characteristics. Finally, a prototype was fabricated and experiments were implemented to verify the feasibility, which shows a high isolation of 19 dB. To the best of our knowledge, the proposed antenna is the first one to achieve HIRF protection through integrated antenna technology, which features with low cost and compact structure, providing a new perspective.

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.