| dc.description.abstract | Because there are more and more applied in the wireless internet
multimedia application. It is more important in the terrestrial microwave
communication. But, because the crowded of the spectrum, many people
tend to choice the Ka-band(26-40GHz) for the application. But this band
is easily to be influenced by the environment, when it transferred in the
atmosphere. Which the most obvious is the attenuation by the rain or the
vegetations. In this article, we will discuss some effect of the rain and the
vegetations.
In the rain effect. We build up a Ka-band terrestrial link to measure
the signal attenuation by rain. We also made the statistics distribution of
the hourly rain rate in Jung-Li, Taipei, Taichung, and Kaoshung(data
offered by CWB). Compared with the most used ITU-R and Crane model,
we find that both them are overestimate. So we try to modify the
coefficients in the ITU-R and Crane model to match the local experiment.
The other side, the data offered by CWB are hourly data, but it is more
appropriate to use minutely data in communication analysis. We also
develop a conversion model to convert the hourly data to minutely data.
After we convert 10 years data in Jung-Li, we suggest that the R0.01 value
in Jung-Li should be 71mm/hr.
In the vegetations effect. We measure the attenuation and made the
probability distribution pass through the mixed, deciduous, and
coniferous trees. We find the effective attenuation rate is 7.24dB/m in
mixed trees, 9.67dB/m in deciduous trees, 1.51dB/m in coniferous trees.
We also find the probability distribution is most fitted to Gamma
distribution in all three types of trees. | en_US |