Compact UHF Circularly Polarized Multi-Band Quadrifilar Antenna for CubeSat.

This article presents a multi-band right-hand circularly polarized antenna designed for the Cube Satellite (CubeSat). Based on a quadrifilar structure, the antenna provides circular polarization radiation suitable for satellite communication. Moreover, the antenna is designed and fabricated using two 1.6 mm thickness FR4-Epoxy boards connected by metal pins. In order to improve the robustness, a ceramic spacer is placed in the centerboard, and four screws are added at the corners to fix the antenna to the CubeSat structure. These additional parts reduce antenna damage caused by vibrations in the launch vehicle lift-off stage. The proposal has a dimension of 77 × 77 × 10 mm3 and covers the LoRa frequency bands at 868 MHz, 915 MHz, and 923 MHz. According to the measurements in the anechoic chamber, antenna gains with the values of 2.3 dBic and 1.1 dBic are obtained for the 870 MHz and 920 MHz, respectively. Finally, the antenna is integrated into a 3U CubeSat that was launched by a Soyuz launch vehicle in September 2020. The terrestrial-to-space communication link was measured, and the antenna performance was confirmed in a real-life scenario.

Is it good to hold more cash before the pandemic? A case of Taiwanese firms.

The Covid-19 pandemic poses a great damage to firm performance worldwide. It raises the empirical question that if any factor can help firm perform better during the pandemic. In this study, we hypothesize that firms holding more cash before the pandemic can perform better during the pandemic year in 2020. We collect all listed firms from Taiwan Stock Exchange and test this hypothesis. Adopting a panel-data regression models with fixed effects, we find supportive evidence that pre-saved cash is valuable and can help firms perform better during the pandemic. Cash-rich firms will have a higher return on equity and return on assets. The economic significance is also non-trivial. Our study thus contributes to our understanding of how the pandemic can affect firm business and which lesson we can learn from this pandemic.

Does loan growth impact on bank risk?

In the context of competition between domestic banks but also foreign banks become more and more fierce. The increasing penetration of foreign banks brings certain risks to domestic banks. This study was conducted to assess the effect of loan growth on banking risk in Vietnam. The study collects data on 29 banks listed on the Vietnam stock exchange from 2010 to 2020. The results of panel data analysis with Generalized least squares (GLS) have shown a relationship between loan growth and bank risk. In which loan growth has a negative impact on Non-performing loans (NPL), liquidity risk equity on asset (ETA); loan growth has a positive impact on return (ROA). In addition, the study also conducts a comparative assessment by bank size and loan growth rate. The results indicate a difference in loan growth's impact on banks' bank risk with lower and higher assets and lower and higher loan growth rates. From the results of this study, the authors also provide some implications to help banks reduce bank risk based on loan growth strategy.