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Projecte llegit

Títol: Radio direction finders for wideband source detection

Estudiants que han llegit aquest projecte:

Director/a: ÚBEDA FARRE, EDUARD

Departament: TSC

Títol: Radio direction finders for wideband source detection

Data inici oferta: 08-02-2021     Data finalització oferta: 08-10-2021


Estudis d'assignació del projecte:
    GR ENG SIS TELECOMUN
Tipus: Individual
 
Lloc de realització: EETAC
 
Paraules clau:
Radio direction finder, radiogoniometer, electronic support measures
 
Descripció del contingut i pla d'activitats:
At the beginning of twentieth century, with the advent of radiocommunications, vessels replaced the traditional lighthouses by navigation schemes based upon radiogoniometers; namely, devices designed to find the direction of a radio source or beacon. The first Radio Direction Finders consisted of rotating coils that identified the incoming direction of radio waves. Ever since, several type of radio direction finders have been developed and applied in several areas; such as, among others, aircraft navigation or Radar jamming detection.
In this work, most of wire-type of radio-direction finders, such as loop-dipole or adcock antennas, will be studied and their radio detection properties will be analyzed. Moreover, insight into circular-array designs, with or without Doppler systems, will also be provided. Also, the monopulse antenna will also be referred. Special focus will be given to the working frequency bandwidth of the several schemes under comparison. If possible, improved designs with optimized wideband performance will be given.
 
Overview (resum en anglès):
Direction finding systems obtain the direction of incidence of an impinging electromagnetic wave. The ultimate goal is to obtain the specific location of the emitting source. To do this, the intersection of the bearings to radio sources from different direction finding stations is sought and triangulation techniques are used.

The aim of this work is to study several direction finding systems. The first part of the study explains the main characteristics and components that a direction-finding system must have: the type of waves it detects, the wave propagation methods it uses and the working frequency bands. this work also addresses the several types of used antennas and their classifications (peak-detection and null-detection), the types of manual and automatic detection strategies (TDOA, Watson-Watt/Adcock, Doppler, etc.), the real applications and finally how to locate the target.

On the other hand, the practical study deals with the behaviour of the firstly conceived antennas. These antennas are the loop antenna, the crossed loop antenna and the Adcock array. These antennas exhibit a 180° ambiguity when it comes to determining the direction of the radio source. To solve this ambiguity, an additional antenna, so-called sense antenna, is used. To study the behaviour of these antennas, the wire-based modelling software 4nec2 has been used. In order to make a rigorous study, we evaluate how the antennas behave from different points of view. Firstly, the antenna is simulated with several sizes and ambiguity in the received direction. Secondly, the behaviour of the antenna with the sensor antenna is addressed. Finally, a bandwidth comparison of all antennas is carried out.

Finally, it was found that it is necessary to apply a mutual coupling correction factor between the antennas used for direction finding and the sensor antenna. The Adcock antenna, based on an Adcock array of dipoles, has a higher bandwidth than those formed by loops.

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