Page 30 - ITU Journal: Volume 2, No. 1 - Special issue - Propagation modelling for advanced future radio systems - Challenges for a congested radio spectrum

ITU Journal: ICT Discoveries, Vol. 2(1), December 2019

finally, assuming the antennas efficiency of 60%. The correlation of the hourly averaged scintillation
The long term average water content of heavy standard deviation and local meteorological data
ℎ
clouds, used in the van de Kamp model, was roughly has been analyzed. A positive correlation was found
estimated as 1 kg/m from [12]. with ambient temperature and the water vapor
2
density and a negative one with the atmospheric
pressure.
The diurnal variation is more observable during the
summer months and the scintillation is more
intense from 10 am to 8 am. The monthly fade and
enhancements distributions show a significant
variability. There is a high correlation between the
hourly scintillation variance at the two frequencies
in spite of the angular separation of the two links.
The variance frequency scaling seems to be well
described by the theory. The best fade and
enhancements model to describe the experimental
data seems to be the Otung one.

Fig. 11 – Cumulative distribution of the enhancements at ACKNOWLEDGEMENT
Ka-band and the predictions of the models for one year
This work was developed in the framework of the
European Space Agency (ESA) funded project Large
Sale Assessment of Ka/Q Band Atmospheric
Channel Using the Alphasat TDP5 Propagation
Beacons, ESA ITT AO/1-7963/14/NL/LvH.
The authors are grateful to ESA and ESA Technical
Officer, Dr. Antonio Martelluci, for funding the
refurbishment of the Ka-band terminal front-end
which extends significantly the receiver dynamic
range.

REFERENCES

[1] A. Rocha, T. Pereira, S. Mota, and F. Jorge,
“Alphasat experiment at Aveiro,” in 2016
Fig. 12 – Cumulative distribution of the fades at Ka-band and 10th European Conference on Antennas and
the predictions of the models for one year
Propagation (EuCAP), 2016, pp. 1–5.
The Otung model seems to give the better
predictions for the enhancements while the van de [2] J. Flávio, A. Rocha, S. Mota, and F. Jorge,
Kamp and Karasawa models under-predicts both “Alphasat Experiment at Aveiro : Data
the fades and enhancements. The ITU model Processing Approach and Experimental
performs reasonably well with the fades. The Results,” in European Conference on
performance of the available models will be Antennas and Propagation, 2017,
systematically evaluated in future work. pp. 2376-2380.
[3] Rec. ITU-R P.453-13, “The radio refractive
6. CONCLUSION index : its formula and refractivity data P
Series Radiowave propagation,” vol. 13, 2017.
A scintillation database has been collected at Aveiro,
Portugal at Ka and Q-band in convergent links. In [4] M. M. J. L. van de Kamp, “Climatic Radiowave
spite of an already existing database at Ka-band, the Propagation Models for the design of Satellite
new one now comprises the Q-band. The Communication Systems,” Eindhoven
experimental conditions were described in detail to University of Technology, 1999.
understand the potentials and limitations of the
database.

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