Communication Engineering

Permanent URI for this collection

http://etd.aau.edu.et/handle/12345678/191

Browse

Browsing Communication Engineering by Author "Abdo, Mohammed (PhD)"

Now showing 1 - 3 of 3
  • No Thumbnail Available
    Item
    Analysis and Design of A Compact Microstrip Patch Antenna With Enhanced Bandwidth and Gain for Wireless Local Area Network (Wlan) Communications
    (Addis Ababa University, 2010-07) Debo, Feyisa; Abdo, Mohammed (PhD)
    In this thesis, the compact microstrip patch antennas in stacked configuration have been proposed. The microstrip patch antenna structure consists of a square patch with four equal u-shape on four sides of each patches. These structures provide an optimized patch area resulting in a substantial reduction in size compared to a typical microstrip square patch designed at the same frequency of operation. The characteristics of the antenna are obtained in terms of return loss, gain, radiation pattern and bandwidth and are compared with the conventional microstrip patch. The stacked configuration enhances both gain and bandwidth of the microstrip patch antenna at 2.45GHZ operating frequency. A size reduction of 70% is obtained along width 24.4dB gain and 6.6519GHZ bandwidth. The empire software is used to obtain the optimized performance of the proposed antenna. This antenna is found to be suitable for WLAN communications. Key Words: size reduction, stacked microstrip patch antenna, gain, bandwidth.
  • No Thumbnail Available
    Item
    Comparative Study on Bandwidth Enhancement Techniques of Microstrip Patch Antenna
    (Addis Ababa University, 2008-01) Hailu, Zewdu; Abdo, Mohammed (PhD)
    Conventional microstrip antennas in general have the attractive features such as low profile, light weight, easy fabrication, and conformability to mounting hosts. However, microstrip antennas inherently have a narrow bandwidth, low gain, and bandwidth enhancement is usually demanded for practical applications. In addition, applications in present-day mobile communication systems usually require smaller antenna size in order to meet the miniaturization requirements of mobile units. Thus, size reduction and bandwidth enhancement are becoming major design considerations for practical applications of microstrip antennas. For this reason, conducting studies to achieve compact and broadband operations of microstrip antennas is thought to be very important. The purpose of this thesis is to make a comparative study on the techniques that help to overcome the bandwidth constraint of microstrip patch antennas and to propose the better technique by taking different consideration such as the antenna gain, bandwidth and related issues. In this thesis work broad banding techniques like using feeding techniques (proximity coupled), stacked patches, parasitic arrangement of patches and the use of different shapes (i.e. E-shaped) are studied. The bandwidth obtained for each type of the antenna are 10.8%, 11.5%, 15.6% and 25.6% respectively with respect to the operating frequency of each of the antennas. The result shows that the E-shaped patch antenna has better performance. Key Words: patch antenna, return loss, bandwidth, gain
  • No Thumbnail Available
    Item
    Investigation of Mobile Station Position Location Technique for Cellular System
    (Addis Ababa University, 2009-08) Kefyalew, Dawit; Abdo, Mohammed (PhD)
    Wireless position location (PL) is a relatively recent technology in the field of wireless communication. The US federal communication commission FCC recommendation is the driving force for PL research since it requires that the wireless service provider include PL service for emergency calls. It is believed the majority of emergency calls come from mobile subscribers. In order to locate these subscribers by public safety answering point (PSAP) a lot of research is going on. Wireless PL is also an attractive business for service provider in the field of advertising, navigation, effective workforce management, information broadcast and other value added services for users. In this thesis an investigation of different PL technique is made. The advantages and disadvantages of the PL techniques are surveyed. Based on the investigation an optimum PL technique proposed. On investigation it is found that most PL techniques need three or more base stations (BS). There should be synchronization among them; which increases the signaling load of the network. Moreover these techniques assume a line of sight signal which is not valid specifically for urban environment. In order to solve this problem, this work focuses on PL technique using single BS using smart antenna. i In an urban environment where line of sight assumption is not valid Fingerprint Matching Technique is an optimum solution. Implementation of this technique across a test route near Tikur Anbessa Hospital shows 67% of location error is less than 72m. For suburban and rural environment with the assumption that at least one line of sight signal is available, a hybrid TOA/AOA technique using smart antenna is found to be an optimum solution for this environment. The simulation result shows that location error below 66m for 67% cab be attained