| 1. |
- Jonsson, B. Lars G., et al.
(author)
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Array Antenna Limitations
- 2013
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In: IEEE Antennas and Wireless Propagation Letters. - 1536-1225 .- 1548-5757. ; 12, s. 1539-1542
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Journal article (peer-reviewed)abstract
- This letter defines a physical-bound-based array figure of merit for both single and multiband array antennas. It provides a measure to compare their performance with respect to return loss, bandwidth(s), thickness of the array over the ground plane, and scan range. The result is based on a sum-rule result of Rozanov-type for linear polarization. For single-band antennas, it extends an existing limit for a given fixed scan-angle to include the whole scan range of the array, as well as the unit-cell structure in the bound. The letter ends with an investigation of the array figure of merit for some wideband and/or wide-scan antennas with linear polarization. We find arrays with a figure of merit >0.6 that empirically defines high-performance antennas with respect to this measure.
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| 2. |
- Kolitsidas, Christos I., et al.
(author)
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A study of partial resonance control for edge elements in a finite array
- 2013
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In: Progress In Electromagnetics Research Symposium Proceedings, Stockholm, Sweden, Aug. 12-15, 2013. - : Electromagnetics Academy. - 9781934142264 ; , s. 253-256
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Conference paper (peer-reviewed)abstract
- This work is focused on developing a method for compensating the edge effects in a mid-sized antenna array. Initially the resonance shift for the E-plane with respect to element position and scan angle was studied in finite × infinite array of strongly coupled dipoles. We show that geometrical tuning on the outermost elements of the array results in a 40% bandwidth improvement at the edge elements for a 40± scan angle. This improvement is compared with the original edge element behavior and it is achieved with a VSWR < 3 for the worst element. These modifications were based into two observations. Primarily, it was shown that by electrically connecting the edge elements we obtain an improvement in the interelement coupling. By adding stripes to the arms of the edge dipoles we obtained an additional degree of freedom that was used to improve the impedance of the edge elements. This procedure resulted in almost uniform VSWR behavior for all elements up to the edge for the finite × infinite approach.
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| 3. |
- Kolitsidas, Christos, et al.
(author)
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Investigation of compensating the ground plane effect through array's inter-element coupling
- 2013
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In: 2013 7th European Conference on Antennas and Propagation (EuCAP). - New York : IEEE. - 9788890701832 ; , s. 1264-1267
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Conference paper (peer-reviewed)abstract
- Bandwidth and directivity are coupled and an increase in directivity provided by a ground plane tends to reduce bandwidth. Over the last decade it has been indicated that highly coupled antenna elements have the ability to provide wide band properties. Such structures often suffer from a bandwidth reduction when they are placed over a ground plane. This study focuses on the interaction between the ground plane and the inter-element coupling. The coupling can partially be modified and hence it can be seen as an extra degree of freedom, a mean to widen bandwidth for strongly coupled arrays in the presence of a ground plane.
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| 4. |
- Kolitsidas, Christos, 1984-
(author)
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Literature review : Wideband/Multiband Antenna Arrays for Base Station Applications
- 2013
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Reports (other academic/artistic)abstract
- The scope of this literature study is to describe the current trends in multiband/wideband antenna arrays with wide scan angle that are applicable to the Chase project: Next Generation Antenna Arrays. The goal of this project is to develop a broadband/multiband antenna array that is able to operate at all commercial wireless protocols and provide wide scan angle capabilities. In the literature two different approaches have been developed for the array design procedure. The first approach, which is the classic design procedure, is based on the element and the array lattice selection. It is then expected that the array inherits the element behavior thus the characteristics of the array would be similar to element characteristics. Using this procedure the interelement coupling is treated as an undesired phenomenon which causes unwanted resonances inside the operating frequency range. Over the last decade a new technique was developed that utilize strongly coupled elements and they showed that these elements can provide wideband array characteristics. The first indicator for this behavior was the Vivaldi array. Here, it was shown that electrically connected Vivaldi elements can provide large bandwidth and wide scan angle range. This breakthrough opened a new research area were strongly coupled elements and coupling mechanisms are investigated, it has also generated a new design approach. This literature survey is organized on these two different approaches. In the first chapter we examine the elements that can provide wideband or multiband characteristics. In the second chapter the most promising strongly coupled arrays are examined and we compare their properties to the project requirements. We end this literature survey with conclusions selecting the most promising technologies.
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