Computer Engineering

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Browsing Computer Engineering by Author "Abayneh, Esuballew"

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    Investigation of Performance of Different Kinds of Dual Band Patch Antennas for Mobile Phones
    (Addis Ababa University, 2007-03) Abayneh, Esuballew; Woldemariam, Woldeghiorgis (Professor)
    Mobile communications handsets with internal antennas become more popular every day. These integrated antennas must be designed to fit into a small volume, with an arbitrary shape. Indeed, the design of modern handsets is mostly fashion-oriented, and the antennas must be adapted to these requisites, without detriment to their matching or radiating performance [12]. The present study focuses on how a change in some of the antenna geometric parameters, such as its height, may affect its actual performance. Dual band antennas are defined as:” Antennas that are useful in situations where the antenna is required to operate in two distinct frequencies which may be too far apart for a single antenna to perform efficiently at both frequencies. [8] In this thesis work different dual band patch antennas for mobile phones are designed, simulated (using the EMPIRE software) and the performance of which is compared based on the standard performance measures. The antenna put into consideration is said to be dual band if it operates on any two of the bands: GSM, DCS, PCS, IMT2000 and Bluetooth bands. A total of 10 patch antenna types: 5 from multiresonator and 5 from reactively loaded patch antennas are considered. Of these the pins loaded patch antenna and a patch loaded with adjustable air gap have better performance as they are closer to the regulatory performance measurement standards compared to the rest. For pins loaded patch antenna the BW is 4.94% around GSM1800 ( f MHz c = 1800 ), 3.04% around IMT ( f MHz c = 2170 ) and 4.08% around Bluetooth ( f MHz c = 2450 ). For the patch loaded with adjustable air gap the BW is 10% around GSM900 ( f MHz c = 900 ) and 2.33% around GSM1800 (DCS) ( f MHz c = 1800 ). In both cases the BW is measured for S 9dB 11 £ − which is the regulatory standard for measuring impedance bandwidth. As these two antenna structures are closer to the regulatory standards of antenna performance measurement, they are suitable for dual band mobile communication handsets except that in the former case the shorting pins complicate the fabrication process.