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For the implementation of high-gain dual-band transmit-arrays, adequate unit-cells have to be designed. The potential difficulty is related to the independent 360° phase wrapping needed at each band to compensate arbitrarily large equivalent path length phase compensation. This points to an intractable number of phase combinations at each band, leading to a possibly very large number of different...
The paper gives a description of the satellite propagation measurement site established in Ljubljana. It consists of two beacon receivers, measuring the Alphasat and Astra 3B beacons at Ka-band and at Q-band, and of a co-located rain gauge. Statistical analysis of collected measurements is performed to create complementary cumulative distribution functions of excess attenuation and rain rate. First...
For the last decades satellite communication systems have been moving towards higher and higher frequencies; rain attenuation along the Earth-satellite path can be an important limiting factor for the system availability, especially in tropical regions where rain events can be particularly intense. One of the possible countermeasures is site diversity. In this paper we evaluate the performance of...
EUTELSAT's first HTS system, KA-SAT, is still the largest in Europe and a benchmark. Since then EUTELSAT has launched EUTELSAT 36C to deliver services over Russia and EUTELSAT 65 West A over LATAM. The Broadband for Africa HTS satellite is currently in production to provide services over Africa. The requirements for HTS systems evolve and are mainly driven by economics trying to drive the cost of...
The paper provides an overview of the most significant space antenna products and technologies for Observation, Exploration and Navigation (OEN) developed by ThalesAleniaSpace-Italia (TAS-I) over more than 30 years. These antennas provided a determinant contribution to the scientific community in understanding earth environment and solar planets. An outline of today key developments is also presented.
The attenuation due to rain is one of the main impairments in satellite communications. It is well known that rain attenuation is dependent on the elevation angle of the link, being more severe at low elevation angles; this has a definite impact on the design of TLC and data download systems based on low earth orbit (LEO) satellites. As measurements at various elevation angles are seldom available,...
This paper presents an overview of the activities performed by the Agency in the framework of the Alphasat Aldo Paraboni scientific experiment at Ka and Q band. In particular it addresses the technological developments for the equipment of the propagation campaign, the execution of mission related activities, the execution of propagation campaigns, the international cooperation with the group of propagation...
The Alphasat telecommunication satellite was launched in July, 2013 and beside of the main payload it carries four scientific experiments. One of them is the Aldo Paraboni Scientific Experiment, a propagation experiment in the Ka and Q radio bands. The experiment is coordinated by the European Space Agency under the framework of ARTES 8 Telecom program. Hungary, similarly to other European experimenters...
The upcoming migration of satellite services to higher bands, namely the Ka- and Q-bands offers many advantages in terms of bandwidth, data rates and system capacity. However, it poses challenges as propagation effects introduced by the various atmospheric phenomena are particularly pronounced in these bands and can become a serious constraint in terms of system reliability and performance. This paper...
In the current work we focus on sparse array design employing overlapping radiating elements. In this case, the underlying sparse grid shapes the broadside directivity far-field pattern while the overlapping flat-top producing sub-arrays eliminate the scanning loses. In detail, when overlapping arrays are involved the design process is as follows: Perform broadside design, (not scanning beam), using...
At lower frequencies, e.g., at S-band, the radome design for ground stations can be considered consolidated, and the microwave transparency can be often obtained with minimal compromises on the structure stiffness. Conversely, at K-band frequencies and above the two domains, electromagnetics and mechanics, require a joint design to achieve best performance, especially when installations at environmentally...
This paper proposes an overview of recent European developments related to broadband satellite applications. Ka-band multi-beam antennas for user links and Q/V-band antennas for feeder links are crucial components to cope with stringent VHTS mission requirements. A brief presentation of technical trends since early 2000 is exposed with a specific focus on multi-beam antenna technology. Also, the main...
The paper presents a dual circular polarization unit cell for realizing a reflectarray that synthesizes two independent patterns based on the polarization of the incident field. To this end, a thin polarizer, which converts incident circularly polarized (CP) waves into orthogonal linearly polarized (LP) waves, is cascaded with a dual-linear-polarization (DLP) reflectarray. The reflectarray then applies...
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