Proper selections of microwave-transmitting thermal control materials play key roles in the orbit operations of aerospace microwave detectors. Currently, white paint and germanium-coated polyimide film are common choices for microwave-transmitting thermal control, which have been extensively studied from the perspective of material compositions, ignoring the influence of the micro-nano structure on the surface of the material. Inspired by Saharan silver ants relying on micro-nano structures of hairs for heat protection and dissipation, in this paper, based on finite element simulation, spectral characteristics (e.g., solar absorptance and infrared emissivity) of three types of biomimetic micro-nano structures (e.g., including pyramid, tetrahedron, and triangular prism) were studied and compared. Simulation results revealed that spectral characteristics of these biomimetic micro-nano structures were mainly regulated by the tip height and the air gap; the decrease of the tip height led to the decrease in the solar absorptance and the infrared emissivity; the solar absorptance was decreased, and the infrared emissivity was increased with the increase of the air gap. When these biomimetic structures were compared with flat surfaces without micro-nano topographies, a decrease of the solar absorptance to block the incidence of heat flow from the sun and an increase of the infrared emissivity to dissipate its own heat to the space were located, which may give suggestions on the adjustment of spectral characteristics of aerospace microwave-transmitting thermal control materials.

The normal operation of spaceborne parabolic cylindrical reflector antennas under various operating conditions relies on maintaining the root mean square (RMS) of the reflector surface’s deformation within reasonable limits. In engineering practice, the designing of reinforced ribs is the primary way to control the RMS of the reflector surface. However, the layout and dimensions of reinforced ribs for many existing designs rely on the experience of the designer and lack a theoretical foundation. This leads to suboptimal layouts and dimensions in many designs, deviating from the optimal design. To address these concerns, this study proposes a comprehensive design approach that combines both topology optimization and parametric analysis. Optimization and parametric analysis were conducted for a large-sized spaceborne composite parabolic cylindrical reflector antenna. The layout and dimensions of the reinforced ribs were reconstructed based on the optimization results and parametric analysis. This study also obtained the influence of the height and thickness of the reinforced ribs on the RMS of the reflector surface. Subsequently, utilizing antenna temperature field simulations as thermal excitation inputs, finite element thermal distortion analyses were conducted for the reflector surfaces without reinforced ribs, with the original reinforced ribs designed based on empirical methods, and with optimized reinforced ribs. In comparison to the original design of the reinforced ribs, the optimized design, without an increase in the volume of the reinforced ribs, reduced the RMS of the reflector surface from 0.6025 mm to 0.5561 mm, resulting in an optimization ratio of 7.7%. Moreover, when compared to the reflector surface without reinforced ribs, the optimized design achieved a 17.9% reduction in RMS.

Biological cell imaging in the sub-terahertz (sub-THz) regime is exceptionally challenging due to the intrinsically low dielectric contrast of weakly scattering specimens. Here, we present a sub-THz scattering-type scanning near-field optical microscopy (s-SNOM) system, specifically engineered to overcome this limitation. Superior near-field sensitivity is achieved through a strategically designed zero-intermediate-frequency (Zero-IF) architecture, featuring high transmitter-receiver isolation (39.95 dB at 105.87 GHz), and a custom-designed probe with a 100 nm tip radius. This probe design deliberately maximizes the near-field scattering efficiency for low-dielectric materials. We validated the system's performance by imaging ovarian cancer cells in three distinct preparations: cell-suspension, thick-sliced (5 μm), and ultrathin-sliced (100-200 nm) samples. The system successfully generated high-fidelity, nanoscale images with signal-to-noise ratio (SNR) up to 50.3 dB, clearly resolving subcellular structures. This success demonstrates the potential of the s-SNOM platform to serve as a powerful label-free, non-invasive imaging tool for cellular biology and clinical diagnostic research.