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A Bandwidth Enhancement Technique for Mobile Handset Antennas using Wavetraps
Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Signal Processing.
Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Signal Processing.
2006 (English)In: IEEE Transactions on Antennas and Propagation, ISSN 0018-926X, E-ISSN 1558-2221, Vol. 54, no 8, 2226-2233 p.Article in journal (Refereed) Published
Abstract [en]

A novel technique for enhancing the impedance bandwidth of wireless terminal antennas is presented. By introducing resonant short circuit transmission lines to the long sides of the chassis edges, an effective electrical shortening of the terminal ground plane is achieved. This effect has been used to realize terminal ground planes with resonant lengths at high frequencies, such as GSM 1800/1900.MHz or UNITS 2 GHz, thereby extending the impedance bandwidth. The proposed technique has been validated by simulations and measurements. Three typical applications are presented where the introduction of wavetraps improves the bandwidth and/or in-band performance.

Place, publisher, year, edition, pages
2006. Vol. 54, no 8, 2226-2233 p.
Keyword [en]
bandwidth, broadband communication, microstrip antennas, mobile antennas
National Category
Engineering and Technology
Identifiers
URN: urn:nbn:se:uu:diva-95373DOI: 10.1109/TAP.2006.879211ISI: 000240116800006OAI: oai:DiVA.org:uu-95373DiVA: diva2:169557
Available from: 2007-01-12 Created: 2007-01-12 Last updated: 2017-12-14Bibliographically approved
In thesis
1. Wideband Active and Passive Antenna Solutions for Handheld Terminals
Open this publication in new window or tab >>Wideband Active and Passive Antenna Solutions for Handheld Terminals
2007 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

This thesis presents solutions and studies related to the design of wideband antennas for wireless handheld terminal applications. A method of electrically shortening the terminal chassis length to obtain resonance at high frequencies has been proposed and evaluated, thereby increasing the antennas impedance bandwidth. No significant effect on the lower frequency band in a dual-band antenna prototype has been observed, making the method suitable for multi-band applications. The chassis has further been utilized as a zero-thickness 0.9 - 2.7 GHz high efficiency antenna by inserting a notch in the chassis center, and a feasibility study for typical phones has been performed. Additionally, the effect of talk position on the chassis wave-mode has been investigated, where the standard equivalent circuit model for terminal antennas has been modified to include the presence of the users head. The model has been used to explain measured and simulated effects concerning frequency detuning, efficiency reduction and bandwidth enhancements when the terminal is placed in talk position.

The use of a hands-free earpiece cord is currently mandatory for FM radio reception as the cord is utilized as antenna. However, there is currently a market driven demand for removing the cord requirement since many modern phones are equipped with speakers and Bluetooth headsets. In this thesis, an active ferrite loop antenna is proposed as an internal replacement/complement with a performance of -23 dB (G/T degradation) compared to a full-size lossless dipole in urban environments. Also, a modification to the cord is suggested for DVB H reception.

Complex matching networks have been investigated to increase the bandwidth of dual band PIFA antennas, and a printed dual band dipole has been integrated with a modified Marchand balun for dual resonance at two separate frequency bands, thus covering the commercial cellular bands 824-960 and 1710-2170 MHz with a single antenna.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2007. 72 p.
Series
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 266
Keyword
Engineering physics, active antennas, impedance matching, dipole antennas, baluns, slot antennas, microstrip antennas, mobile antennas, multifrequency antennas, antenna proximity factors, receiving antennas, ferrite devices, Teknisk fysik
National Category
Signal Processing
Identifiers
urn:nbn:se:uu:diva-7445 (URN)978-91-554-6779-2 (ISBN)
Public defence
2007-02-02, Polhemsalen, Ångström Laboratory, Lägerhyddsvägen 1, Uppsala, 10:45
Opponent
Supervisors
Available from: 2007-01-12 Created: 2007-01-12 Last updated: 2016-05-02Bibliographically approved

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Lindberg, PeterÖjefors, Erik

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