Page 15 - 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

ALPHASAT site diversity experiments in Greece and the UK at Ka band:
Comparison of 2–years’ results

Pages 45-52

Apostolos Z. Papafragkakis, Spiros Ventouras, Charilaos I. Kourogiorgas, Athanasios D. Panagopoulos
Satellite communications have already started to employ mmWave bands such as the Ka-band (20/30GHz) for
broadcasting and broadband services; Ka-band is used either for backhauling (feeder links) or direct-to-user
services. To enhance the propagation modeling and assist in the development of advanced satellite radio
systems, two site diversity experiments are simultaneously conducted in Greece and in the UK using the
satellite beacon transmitted by ALPHASAT. In this paper, the two years of collected experimental data are
presented and evaluated in terms of first-order statistics. Considering the different climate of the two
experiment locations, one in the Southern Mediterranean Sea (Greece) and one in the Northern Atlantic Sea
(UK), a comparison between the two respective Ka-band long-term radio diversity channels is also performed.
Several conclusions for the diversity system design are drawn that can be particularly significant towards the
application of a smart gateway diversity concept in feeder links.

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Analytic models for bi-static scattering from a randomly rough surface with complex
relative permittivity

Pages 53-58

Mostafa A. Karam, Ryan S. McDonough
This study provides explicit mathematical formulations for the bi-static scattering coefficient from a randomly
rough surface with a complex relative permittivity based on the following analytic models: Small perturbation
model (SPM), Physical optics model (PO), and Kirchhoff approximation model (KA). Then it addresses the
two shortcomings associated with each of the three models: i) limited applicability domain, and ii) null
predicted values for the cross-polarized bi-static scattering coefficients within plane of incidence. The plane
of incidence contains both backscattering direction and forward (specular reflection) direction which are of
interest to the spectrum community.

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