| Summary: | 碩士 === 國立中山大學 === 電機工程學系研究所 === 88 === This thesis uses a method called "parabolic equation approach."
This method can treat both the variations of the terrain and the
refractive index simultaneously. This method makes it possible
to predict the radio propagation more precisely. We can discuss
the effects of the variations of the refractive index to radio
signal and demo effects by using parabolic equation method.
The Effective Earth Radius Factor is 4/3 suggested by CCIR so-called
"Standard Atmosphere Model". But we try to find more suitable K in
the Southern Taiwan area. We adopt Parabolic Equation Propagation
Model to simulate real situation of radio propagation in the Southern
Taiwan area and the prediction is compared with the measurement
obtained previously. We can get the best K in the Southern Taiwan
area is 1.8 and 1.9. The best K is greater than the value of 4/3
suggested by CCIR.
Recently the government on Taiwan release more radio broadcasting
licenses to the general public. As the number of radio stations
increases, the interference between stations becomes more likely.
There have been reports about the poor quality of broadcasting from
stations. In this paper, we will study the interference using FM
radio stations as an example. Given the characteristics of the
transmitting antenna including location, frequency, pattern, height
and power, the field strength can be computed with the equivalent
earth radius factor K as a parameter. The difference in interference
level is obtained under the standard atmosphere (K=4/3) and a case of
K=1.55 which has been reported to be more suitable in Taiwan. Finally
an extreme case that a ducting exists will be studied.
Our results can be used to find more suitable separation distances free
from interferences between co-channel and adjacent channel stations.
By including a realistic tropospheric term, the more accurate field
strength predictions can give the Spectrum Authority a better spectrum
assignment tool. This has the potential to increase the number of
available stations that can be made available or to reduce the
interference stations may experience.
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