One of the types of antennae used in telecommunications systems is that known as antennae groups or arrays, involving the positioning of several antennae close to each other. "One of the advantages is that the signal can be directed from one place or another without the need to continuously reposition the antennae or creating radiation in some specific manner", explained Alberto Reyna, "because it is something that can be done electronically: managing the characteristics of the radiation. In the development of the research, we did this with various types of antennae arrays: square, circular rings, linear, etc."
Basically it approaches a problem presented by satellite communications: "on positioning an array of antennas on the satellite, it becomes very voluminous, heavy and it makes the creation of radiation complicated. For example, having the antennae connected to a different amplifier, with different amplification gain value causes some of them to heat up more than others and thus, some way has to be found of dissipating the heat in space, where there is no air".
To solve this without losing the radiation performance of the antenna array, methods inspired in Darwin's theory of evolution were used "where the antennae array would be an individual which evolves with time with ever-increasingly better adaptation", and in the social behaviour of species, "for example, in order to solve a problem, flocks of birds follow a leader of the species to arrive at some specific point.
According to this researcher, "we opted to design antennae arrays with evolutionary methods, in such a way that, instead of connecting each antenna to an amplifier with different amplification gain value, we could use one amplifier for several antennae; for example, I can have sixty antennae with only three amplifiers and thus achieve a reduction in size, volume, weight and the heat generated in the satellite will not be so difficult to dissipate; all this while still maintaining the performances of the radiation".
Finally, the arrays of antennae are designed in order to achieve isoflux-type radiation, which manages to make the energy received by the Earth to be equal at any point thereon. "The Earth being squashed at the poles and having an elliptical shape, the signal coming from the satellite is delayed or may lose energy; thus, we designed the array of antennae so that the signal has a shape similar to that of a cone, in order to encompass the whole of the Earth's surface equally", explained Mr Reyna. "In short, it can be said that we have designed a type of array of antennae for satellite which manages that the radiation is uniformly incident on all parts of the Earth, thus avoiding some zones receiving more energy than others".
The PhD "Evolutionary Antenna Arrays Synthesis for Isoflux Radiation in Satellite Applications" was led by doctors Marco Antonio Panduro from the Autonomous University of Tamaulipas (México) and Carlos del Río Bocio from the UPNA, and was awarded excellent cum laude. As a result of this research, there have been six scientific articles published in specialist journals and four presentations at international congresses. Mr Reyna undertook his studies at the Reinosa Rodhe Multidisciplinary Academic Unit, where he also completed his Masters, prior to doing his PhD at the UPNA. He is currently working as a research collaborator at the previously mentioned Unit at the Autonomous University of Tamaulipas (México).
Provided by Elhuyar Fundazioa
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