Implementation of a Bluefooth antenna for a mobile phone accessory

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Helsinki University of Technology | Diplomityö
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Date

2007

Major/Subject

Radiotekniikka

Mcode

S-26

Degree programme

Language

en

Pages

79

Series

Abstract

In this thesis the possibility of implementing a Bluetooth antenna in a mobile phone accessory with a metallic surface is investigated. The antenna is implemented in such a way that the metal surface will act as the radiating element. Mobile phone accessories are often small in size and require an antenna that does not require much space. The small size sets performance limits such as low bandwidth and efficiency for an antenna and a good performance in a changing environment can be difficult to achieve. Antenna performance is often directly related to the volume of the antenna structure. By implementing the antenna onto a metal chassis the entire surface of the product is in use and thus better performance can be achieved. The optimal antenna models and dimensions are found through theoretical analysis and simulations. Antenna performance was evaluated by examining the impedance bandwidth and radiated and total efficiency. The smallest dimensions that limit the performance of the antenna were also investigated for a few possible solutions. If the metal surface of a mobile phone accessory is used as a Bluetooth antenna, the small antenna limitations are usually not a problem and the antennas can be made very broadband and efficient. Drawbacks that are related to metal cover antennas are performance in use position and the difficulty of implementing the feed structure of the antenna. Two dipole antennas and one slot antenna are made based on the most promising simulations. The dipole antennas have very wide impedance bandwidth and have quite good performance in use position. Comparing with the dipoles the slot antenna has got narrower impedance bandwidth and also performs worse in use position, but still, it fulfils the performance requirements.

Description

Supervisor

Vainikainen, Pertti

Thesis advisor

Toivanen, Timo

Keywords

Bluetooth antenna, Bluetooth antenn, mobile phone accessory, mobiltelefonstillbehör, radiation efficiency, verkningsgrad, impedance bandwidth, impedansbandbredd, thick dipole, tjock dipol, slot antenna, slitsantenn

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