Tanemasa Asano

Low-emissivity glazing reduces heat transfer, but its continuous fluorine-doped tin oxide (FTO) coating attenuates wireless signals. A two-scale coating-budget framework treats coating removal as a cost to minimize inside the patterned window and over the whole pane. A laboratory insulating-glass unit of commercial K-Glass was laser-patterned over a 50 mm × 50 mm window on both cavity-facing surfaces with hexagonal-ring and square-patch arrays. The coating was modeled as a lossy sheet (design sheet resistance 17 Ω/sq; measured 12.4 ± 0.2 Ω/sq). Full-wave simulation predicts an intrinsic 0.7–6 GHz passband with ≈1.5 dB mean insertion loss, reproduced by a fitted equivalent-circuit model to 0.37 dB. Angular modeling keeps the passband to 40° for both polarizations (transverse-electric loss up to ≈3.5 dB); oblique incidence was not measured. Single-mounting free-space measurements show ≈15 dB mean transmission recovery over 1–6 GHz relative to the unpatterned unit; an independent campaign gives ≈19 dB at 2.4 GHz. Inside the patterned window, 47% of the coating is removed, yet 98.3% of the front-pane and 99.1% of the rear-pane coating remain on the 300 mm × 300 mm panes (98.7% combined). Area-averaged estimates bound the per-pane visible-transmittance change to 1.7 percentage points and emissivity rise to 0.012; neither was measured.

Investigating the performance of power electronics devices and thus power inverters at cryogenic temperatures for electric aircraft systems are of great interest. Accordingly, the purpose of this study is to examine the inverter circuit technologies used in cryogenically-cooled electric aircraft applications from three perspectives: inverter topologies, power capabilities, and electromagnetic interference (EMI) that may occur. At a cryogenic temperature, the characteristics of five power semiconductor switches with different technologies (Si MOS, SiC MOS, and GaN HEMT) used in cryogenically-cooled electric aircraft inverters were tested and the results were presented. Furthermore, the low-temperature performance of three types of capacitors commonly used in power electronics inverters was investigated. The research findings provide crucial considerations for the research and development of power inverters cooled by sub-cooled liquid nitrogen for modern electric aircraft.