This letter proposes a compact 435 MHz telemetry, tracking, and command (TT&C) CubeSat antenna, which does not require an in-orbit deployment mechanism for proper operation. It uses characteristic modes on spacecraft's body to increase the radiating aperture, resulting in a λ/4 sized antenna (as calculated along diagonal of the cube). The antenna aims to provide reliable communication, operating independently from spacecraft's orientation and does not rely on proper deployment of vulnerable mechanical components. The limited space in the launcher limits any protrusions to no more than 6 mm (1/115th of the wavelength) from the spacecraft's wall, which results in low input impedance of 0.4 - 3.2j. To overcome this issue, a differential feeding structure is proposed that incorporates a power divider with impedance matching circuit. It also incorporates a lumped capacitor that can adjust the antenna's operating frequency. The antenna offers a dipolelike radiation pattern with performances comparable to larger deployable UHF antennas. It is intended for reliable TT&C.

Accurate pigment classification is essential for the analysis and conservation of historical paintings. This study presents a non-invasive approach based on supervised machine learning for classifying pigments using image data acquired under three distinct spectral illumination conditions: visible-light reflectography (VIS), ultraviolet false-color imaging (UVFC), and infrared false-color imaging (IRFC). A dataset was constructed by extracting 32 × 32 pixel patches from pigment samples, resulting in 200 classes representing 40 unique pigments with five preparation variants each. A total of 600 initial raw images were acquired, from which 4000 image patches were extracted for feature engineering. Feature vectors were obtained from visible reflectography, ultraviolet false-color imaging (UVFC), and infrared false-color imaging (IRFC) using statistical descriptors derived from RGB channels. This study demonstrates that accurate pigment classification can be achieved with a minimal set of three illumination types, offering a practical and cost-effective alternative to hyperspectral imaging in real-world conservation practice. Among the evaluated classifiers, the random forest model achieved the highest accuracy (99.30 $\pm 0.15$%). The trained model was subsequently validated on annotated regions of historical paintings, demonstrating its robustness and applicability. The proposed framework offers a lightweight, interpretable, and scalable solution for non-invasive pigment analysis in cultural heritage research that can be implemented with accessible imaging hardware and minimal post-processing.

This Letter presents a multi‐half‐loop wideband antenna operating over a ground plane. The proposed structure has a voltage standing wave ratio <2 in the frequency range of 0.95–12.5 GHz (171%). One important attribute of this antenna is robust power‐handling, combined with a super‐wide operating bandwidth. The structure's simplicity allows robustness and easily predictable radiation properties, beneficial for several measurement systems. The antenna can be easily optimised by 4NEC2 freeware. To manufacture the antenna, only the simple mechanical treatment of metal is necessary.