Initial Investigations into the Effects of Mutual Coupling and Architecture of the EISCAT3D array
2013 (English)Conference paper, Poster (Other academic)
To study the layers of the ionosphere and also the interactions between Earth and Sun, the EISCAT association will build a three dimensional imaging radar: EISCAT3D. The infrastructure of the radar system will include 5 sites with ~10000 antenna elements each.
For such arrays, the electromagnetic interaction between radiating elements (coupling effects) and the influence of the ground plane cannot be neglected. In addition, for array applications requiring a large number of elements, a process called thinning is most often applied to remove elements while maintaining much of the same characteristics for the antenna. When the density of components decreases, the coupling in the array will decrease as well.
The relative position of elements doesn’t have a great influence on the performance of main beam. It has, however, on the mutual coupling that changes the input impedance of the radiators and the characteristics of the radiation pattern. The challenge is to find a layout where radiating elements will be separated enough for them not to couple but close enough to not disturb the performance of the array antenna.
For the purpose of analyzing the performance of the EISCAT3D array, a simulation tool has been developed in Matlab/ Mathematica. In this initial study, thinned arrays with three types of elements: isotropic, half wavelength dipoles and an antenna element designed and simulated at Luleå Technical University are investigated. The latter element was designed with the ambition to meet the rigorous requirements put on the EISCAT3D array when deployed in the Northern part of Scandinavia in order to withstand the harsh environment. The radiation pattern of the single radiator is provided by an EM simulation tool (NEC2) and
includes the mutual coupling to identical elements. Thus, analyzing the radiation pattern of the array with Luleå elements, the mutual coupling effects are taken into consideration.
In the simulations an attempt is made to, in a realistic manner and for different scanning angles, calculate performance indicators such as Directivity and Sidelobe level. When the main beam is directed towards the zenith, it was found that between the three elements analyzed, dipoles will result in the lowest directivity and the smallest side lobe level. The directivity of the array with isotropic elements and Luleå elements increases with a regular pattern with increasing number of elements. Between the three types of radiators, Luleå elements will results in the highest average side lobe level and the peak side lobe level gets better than isotropic elements when more than 60% of elements are active.
Place, publisher, year, edition, pages
Research subject SRA - ICT
IdentifiersURN: urn:nbn:se:kth:diva-140726OAI: oai:DiVA.org:kth-140726DiVA: diva2:692546
16th International EISCAT symposium, 12-16 August 2013, Lancaster UK
QC 201502232014-01-312014-01-312015-03-03Bibliographically approved