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A Simple Compact Reconfigurable Slot Antenna With a Very Wide Tuning Range
KTH, School of Electrical Engineering (EES), Electromagnetic Engineering.
KTH, School of Electrical Engineering (EES), Electromagnetic Engineering.ORCID iD: 0000-0002-3401-1125
2010 (English)In: IEEE Transactions on Antennas and Propagation, ISSN 0018-926X, E-ISSN 0096-1973, Vol. 58, no 11, 3725-3728 p.Article in journal (Refereed) Published
Abstract [en]

A simple and compact slot antenna with a very wide tuning range is proposed. A 25 mm (roughly equal to lambda(H)/8, where lambda(H) corresponds to the highest frequency of the tuning range) open slot is etched at the edge of the ground. To achieve the tunability, only two lumped elements, namely, a PIN diode and a varactor diode are used in the structure. By switching the PIN diode placed at the open end of the slot, the slot antenna can resonate as a standard slot (when the switch is on) or a half slot (when the switch is off). Continuous tuning over a wide frequency range in those two modes can be achieved by adjusting the reverse bias (giving different capacitances) of the varactor diode loaded in the slot. Through optimal design, the tuning bands of the two modes are stitched together to form a very wide tuning range. The fabricated prototype has a tuning frequency range from 0.42 GHz to 1.48 GHz with S11 better than -10 dB, giving a frequency ratio (f(R) = f(u)/f(L)) of 3.52:1. The measured full spherical radiation patterns show consistent radiation characteristics of the proposed antenna within the whole tuning range.

Place, publisher, year, edition, pages
2010. Vol. 58, no 11, 3725-3728 p.
Keyword [en]
Compact antenna, slot antenna, tunable antenna
National Category
Electrical Engineering, Electronic Engineering, Information Engineering
URN: urn:nbn:se:kth:diva-96247DOI: 10.1109/TAP.2010.2071347ISI: 000283940100037OAI: diva2:529865
QC 20120530Available from: 2012-05-31 Created: 2012-05-31 Last updated: 2013-11-19Bibliographically approved
In thesis
1. Decoupling and Evaluation of Multiple Antenna Systems in Compact MIMO Terminals
Open this publication in new window or tab >>Decoupling and Evaluation of Multiple Antenna Systems in Compact MIMO Terminals
2012 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Research on multiple antenna systems has been a hot topic in recent years due to the demands for higher transmission rate and more reliable link in rich scattering environment in wireless communications. Using multiple antennas at both the transmitter side and the receiver side increases the channel capacity without additional frequency spectrum and transmitted power. However, due to the limited space at the size-limited terminal devices, the most critical problem in designing multiple antennas is the severe mutual coupling among them. The aim of this thesis is to provide compact, decoupled and efficient multiple antenna designs for terminal devices. At the same time, we propose a simple and cost effective method in multiple antenna measurement. All these efforts contribute to the development of terminal devices for the fourth generation wireless communication.

The background and theory of multiple antenna systems are introduced first, in which three operating schemes of multiple antenna systems are discussed. Critical factors influencing the performance of multiple antenna systems are also analyzed in details. To design efficient multiple antenna systems in compact terminals, several decoupling methods, including defected ground plane, current localization, orthogonal polarization and decoupling networks, are proposed. The working mechanism and design procedure of each method are introduced, and their effectiveness is compared. Those methods can be applied to most of the terminal antennas, reducing the mutual coupling by at least 6dB.

In some special cases, especially for low frequency bands below 1GHz, the chassis of the device itself radiates like an antenna, which complicates the antenna decoupling. Thus, we extend the general decoupling methods to the cases when the chassis is excited. Based on the characteristic mode analysis, three different solutions are provided, i.e., optimizing antenna locations, localizing antenna currents and creating orthogonal modes. These methods are applied to mobile phones, providing a more reliable link and a higher transmission rate, which are evaluated by diversity gain and channel capacity, respectively.

In order to measure the performance of multiple antenna systems, it is necessary to obtain the correlation coefficients. However, the traditional measurement technique, which requires the phase and polarization information of the radiation patterns, is very expensive and time consuming. In this thesis, a more practical and convenient method is proposed. Fairly good accuracy is achieved when it is applied to various kinds of antennas.

To design a compact and efficient multiple antenna system, besides the reduction of mutual coupling, the performance of each single antenna is also important. The techniques for antenna reconfiguration are demonstrated. Frequency and pattern reconfigurable antennas are constructed, providing more flexibility to multiple antenna systems.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2012. xvi, 89 p.
Trita-EE, ISSN 1653-5146 ; 2012:025
Multiple antennas, mutual coupling, compact antennas, frequency reconfigurable antennas, pattern reconfigurable antennas, meta-material antennas, mobile antennas, fractal antennas, collocated antennas, antenna measurement.
National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering
urn:nbn:se:kth:diva-96239 (URN)
Public defence
2012-06-15, H1, Teknikringen 33, KTH, Stockholm, 10:00 (English)
QC 20120604Available from: 2012-06-04 Created: 2012-05-31 Last updated: 2012-06-04Bibliographically approved

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