We reported a bandgap-tunable device with ternary plasma photonic crystals (PPCs), achieving tunable bandgap for controlling the propagation of free-space electromagnetic waves from 11.5 GHz to 14.5 GHz. The device is designed as a square crystal structure composing ternary PPCs arrays. Both simulation and experimental results indicate that the transmission of the electromagnetic waves can be controlled by changing the plasma frequency, dielectric constant, and structure spacing in the device, realizing the dynamic adjustment of photonic bandgap bandwidth and center frequency. In addition, the plasma frequency was measured, which is consistent with the simulation results. Our strategy can be applied to design a variety of devices, including reconfigurable antennas, plasma lenses, and military-developed stealth equipment.

We study the pointwise (in the space and time variables) behavior of the linearized Landau equation for hard and moderately soft potentials. The solution has very clear description in the (x, t)−variables, including the large time behavior and the asymptotic behavior. More precisely, we obtain the pointwise fluid structure inside the finite Mach number region, and exponential or sub-exponential decay, depending on interactions between particles, in the space variable outside the finite Mach number region. The spectrum analysis, regularization effect and refined weighted energy estimate play important roles in this paper.

Conventional plasma absorbers are challenging to obtain high electron density and sizeable spatial scale for effective absorption while meeting the applied requirements of low profile and low power consumption. Although the frequency selective surface (FSS) has proved to realize a lower profile of plasma absorber with some empirical patterns adequately, the issue of the FSS design matching the dispersion distribution of complicated plasmas is still in suspense. A reverse prediction method referenced as the forecast and design Conditional Generative Adversarial Network (FD-CGAN) is proposed to generate a pixelated FSS between double-layer plasma periodic arrays. The reflection attenuation characteristics examined by experiments show that the addition of the FSS makes the coupling absorption effect surpass that of either pixelated FSS or plasma solely. Measurements in reconfigurable working modes and array arrangements demonstrate that the proposed configuration maximizes absorption effectiveness in the same profile, accompanied by the simulation. An interfacial void model is proposed to assist the design of the composite absorbing structure, together with an equivalent circuit for the hybrid absorber including periodic patterns with stochastic distribution characteristics, which analyze the absorption effect of the composite structure. The study provides a new approach for various microwave applications, including multilayer radarabsorbing structures, plasma-based stealth technology, and reconfigurable filters.

No abstract

No abstract