A transmission-reflection-integrated multifunctional metasurface (TRMM) has been proposed, capable of switching between transmission and reflection modes. The switchable characteristics is achieved by integrating a broadened orthogonal grating structure with PIN diodes. By incorporating an artificial magnetic conductor (AMC) with varactors, the polarization of incident waves can be controlled as altering the surface impedance distribution. Simulation and experimental results indicate that in the frequency range of 3.67-4.44 GHz, incident waves are reflected in the form of cross-polarization, with a maximum reflection amplitude of -1.27 dB and a relative bandwidth of 19%. The frequency range shifts as the capacitance value of the varactor is adjusted. When the metasurface operates in the transmissive mode, the outgoing wave maintains polarization along the y-direction, regardless of the polarization direction of the incident electromagnetic wave along the x or y-direction. The center frequencies are 4.26 GHz (x polarization) and 4.89 GHz (y polarization), with maximum transmission coefficients of -2.23 dB and -3.0 dB, respectively. This study overcomes the limitations associated with half-space electromagnetic (EM) waves by regulating the transmission and reflection of EM waves throughout the entire space, as well as effectively controls the polarization parameters within specific frequency bands. This advancement significantly expands the coverage range of communication systems and offers a novel technical solution for high-performance radar detection, intelligent antenna systems, and various other applications.

In this paper, an active metasurface possessing beam scanning capability at 35 GHz is presented. By changing the capacitance value of varactor diodes loaded on the coaxial annular aperture structure(CAA) with high transmission efficiency, the variation range of the phase gradient can be tuned, resulting in the change of radiation angle. Therefore the metasurface can be applied on wide angle beam scanning antenna.

Herein, a reconfigurable multifunctional transmission metasurface polarizer, structured with double Jerusalem crosses and integrated with four PIN diodes, is presented. The bottom Jerusalem cross is rotated by 35∘ with respect to the top cross. Both numerical and experimental observations reveal that a linearly polarized (LP) outgoing wave is transmitted at approximately 4.0 GHz when subjected to a left-handed circularly polarized (LCP) or right-handed circularly polarized (RCP) incident wave. The transmission efficiency reaches -2.5 dB when all elements are in the ON state. Furthermore, active control of switchable PIN diodes operating in various statuses unequivocally demonstrates the ability to convert an incident wave polarized in the x or y direction to a LCP or RCP wave, respectively, within the identical frequency band, spanning from 3.6 GHz to 4.3 GHz. This conversion is achieved with a transmission coefficient of -3.5 dB or -4.2 dB at the peak frequency. The proposed metasurface polarizer presents a potentially dynamic method for simultaneously manipulating various polarization conversions of electromagnetic (EM) waves within a desired frequency band.

An active transmission-type metasurface is presented, which is based on double metallic patches incorporated with active components of PIN diodes. It can be numerically obtained that the left circularly polarized(LCP) wave is transmitted at 4.3-4.48 GHz with a transmission coefficient of 25-46% under the OFF state of PIN diodes when the the structure is impinged by a $x$ polarization. In addition, the ability of converting a y- polarized incident wave to a right circularly polarized(RCP) wave at the same frequency band is unambiguously exhibited with a transmission coefficient of 29.2-43.4% by actively controlling switchable PIN diodes. The proposed metasurface could be an active and dynamic approach to manipulate linear to circular(LTC) polarization conversion at a fixed frequency band.

Deep learning-based synthetic aperture radar (SAR) automatic target recognition (ATR) methods exhibit a tendency to overfit specific operating conditions—such as radar parameters and background clutter—which frequently leads to high sensitivity against variations in these conditions. A novel electromagnetic reconstruction feature alignment (ERFA) method is proposed in this paper, which integrates electromagnetic reconstruction with feature alignment into a fully convolutional network, forming the ERFA-FVGGNet. The ERFA-FVGGNet comprises three modules: electromagnetic reconstruction using our proposed orthogonal matching pursuit with image-domain cropping-optimization (OMP-IC) algorithm for efficient, high-precision attributed scattering center (ASC) reconstruction and extraction; the designed FVGGNet combining transfer learning with a lightweight fully convolutional network to enhance feature extraction and generalization; and feature alignment employing a dual-loss to suppress background clutter while improving robustness and interpretability. Experimental results demonstrate that ERFA-FVGGNet boosts trustworthiness by enhancing robustness, generalization and interpretability.

An active transmission-type metasurface is presented, which is based on double metallic patches incorporated with active components of PIN diodes. It can be numerically obtained that the left circularly polarized(LCP) wave is transmitted at 4.3-4.48 GHz with a transmission coefficient of 25-46% under the OFF state of PIN diodes when the the structure is impinged by a $x$ polarization. In addition, the ability of converting a y- polarized incident wave to a right circularly polarized(RCP) wave at the same frequency band is unambiguously exhibited with a transmission coefficient of 29.2-43.4% by actively controlling switchable PIN diodes. The proposed metasurface could be an active and dynamic approach to manipulate linear to circular(LTC) polarization conversion at a fixed frequency band.