# Millimeter Wave Attenuation Due to Wind and Heavy Rain in a Tropical Region
## 5 Conclusions  
This article presents the first field trial of the E-band FWS link in a tropical location which considers the combined rain attenuation and wind-induced attenuation. The data were analyzed using the current ITU-R P.530-18 rain attenuation model and APT-AWG-REP-81 wind-induced attenuation model. The data showed wind-induced attenuation is significant in this frequency region. By combining both models, the worst-case link budget could be estimated. Although the pole inclination angle and thus the wind-induced attenuation can be estimated via wind speed using the APT report, the direct inclination angle measurements enabling detailed weather effects which account for different inclination directions can be applied to new locations with different weather conditions. Further work can be performed to study the practical effects of wind and rain in FWS link performance, and to develop a compensation technique to ensure stable performance.  
**Supplementary Materials:** The following supporting information can be downloaded at: [[https://www.mdpi.com/article/10.3390/s23052532/s1](https://www.mdpi.com/article/10.3390/s23052532/s1)]([https://www.mdpi.com/article/10.3390/s23052532/s1](https://www.mdpi.com/article/10.3390/s23052532/s1)). Figure S1: beam misalignment angle due to pitch inclination; Figure S2: beam misalignment angle due to side inclination; Figure S3: comparison of gain degradation by pitch and side inclinations; Figure S4: diagram of the actual link and existing buildings between the path; Table S1: primary Fresnel zone clearance data.  
**Author Contributions:** Conceptualization, T.K. and A.K.; methodology, T.K., A.K., Z.-K.W., P.C., U.M. and S.P.; software, A.K., P.C. and S.N.; validation, U.M., Z.-K.W. and P.T.D.; formal analysis, U.M., S.N., Z.-K.W. and P.T.D.; investigation, P.C., S.P. and S.N.; resources, T.K. and A.K.; data curation, U.M. and S.N.; writing--original draft preparation, U.M. and S.N.; writing--review and editing, Z.-K.W., P.T.D., T.K. and A.K.; visualization, U.M. and S.N.; supervision, T.K.; project administration, T.K. and U.M.; funding acquisition, T.K. and U.M. All authors have read and agreed to the published version of the manuscript.  
**Funding:** This paper includes research results from works funded by the Commissioned Research (No. 00302, No. 00401, No. 04301, No. 04901 and No. 06001) of National Institute of Information and Communications Technology (NICT), Japan, and also results from research conducted under the contract \"R&D of high-speed THz communication based on radio and optical direct conversion\" (JPJ000254) made with the Ministry of Internal Affairs and Communications of Japan. This research has received funding support from the NSRF via the Program Management Unit for Human Resources & Institutional Development, Research and Innovation [grant number B05F640218], National Higher Education Science Research and Innovation Policy Council. Partial support from Chiang Mai University is also acknowledged.  
**Institutional Review Board Statement:** Not applicable.  
**Informed Consent Statement:** Not applicable.  
Figure 18: Probability of misalignment and realignment events due to wind gusts over the measurement period, at different RSSI shift thresholds.  
Data Availability Statement: The data presented in this study are available on request from the corresponding author.  
We would like to acknowledge Ministry of Digital Economy and Society and Office of the National Broadcasting and Telecommunications for the experiment endorsement. We would like to thank NEC Corporation for providing the E-band radio units.  
The authors declare no conflict of interest.