EEE412 Antennas and Propagation by l50J1n6c

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									    EEE412 Antennas and Propagation




                              Lecture2
                        Asst. Prof. Dr. Özgür TAMER



Antenna Lecture Notes                             Asst. Prof. Dr. Özgür Tamer
    Introduction

         Course Outline
             theory of electromagnetic radiation
             fundamental antenna parameters
             classical radiating elements
             matching techniques
             antenna arrays
             different antenna types




Antenna Lecture Notes                               Asst. Prof. Dr. Özgür Tamer
    Introduction

        Course Homepage:
            http://eee.deu.edu.tr/~tamer/class.html

        Textbooks
            C. A. Balanis, Antenna Theory, Analysis and Design,
             3rd ed. Hoboken, NJ: Wiley, 2005
            Warren L. Stutzman and Gary A. Thiele, Antenna
             Theory and Design 2nd ed., Wiley




Antenna Lecture Notes                                  Asst. Prof. Dr. Özgür Tamer
    Introduction to Antennas

    History:
    • J.C. Maxwell:
       Mathematical model of
       Electromagnetism
       (1873)
    • Maxwell’s Equations




Antenna Lecture Notes          Asst. Prof. Dr. Özgür Tamer
    Introduction to Antennas

                        • H.R. Hertz:
                          • First wireless EM system
                            in 1886.
                          • A spark appears 20 m.
                            away.
                          • A halw wavelength
                            dipole of 4 m. long




Antenna Lecture Notes                   Asst. Prof. Dr. Özgür Tamer
    Introduction to Antennas

    • Alecander Popov
        • May 7 1985
        • A telegraph message is sent
          from a ship 30 miles away to
          his lab in St. Petersburg




Antenna Lecture Notes                    Asst. Prof. Dr. Özgür Tamer
    Introduction to Antennas

                        • Nicola Tesla
                          • 1892 Presentation at the
                            IRE of London about
                            transmitting intelligence
                            without wires,”
                          • 1895, transmits signals
                            detected 80 km away




Antenna Lecture Notes                    Asst. Prof. Dr. Özgür Tamer
    Introduction to Antennas

    • G. Marconi
        • 1901, performs the first
          transatlantic transmission
          from Poldhu in Cornwall,
          England, to Newfoundland,
          Canada.
        • 1909, Receives Nobel Prize




Antenna Lecture Notes                  Asst. Prof. Dr. Özgür Tamer
    Introduction to Antennas

        The antenna is the transition between a guiding
         device (transmission line, waveguide) and free
         space.




Antenna Lecture Notes                          Asst. Prof. Dr. Özgür Tamer
    Introduction to Antennas
                                              Antenna as a Transmitter
          Transmission Line Equivalent
             Vg: Transmitter Source
             Zg: Transmitter Impedance
             Zc: Transmission Line
              Imp.
             Rrad: Radiation Resistance
             RL: Loss Resistance
             jXA:Antenna Reactance
                                                  Antenna as a Receiver
          Antenna Impedance
            ZA=(Rrad+RL)+jXA




Antenna Lecture Notes                                       Asst. Prof. Dr. Özgür Tamer
    Types of Antennas
    Wire Antennas

    Single Wire         Loop   Helix




Antenna Lecture Notes           Asst. Prof. Dr. Özgür Tamer
    Types of Antennas

    Aperture Antennas




Antenna Lecture Notes   Asst. Prof. Dr. Özgür Tamer
    Types of Antennas

    Printed Antennas




Antenna Lecture Notes   Asst. Prof. Dr. Özgür Tamer
    Types of Antennas

    Reflector Antennas




Antenna Lecture Notes    Asst. Prof. Dr. Özgür Tamer
    Types of Antennas

    Lens Antennas




Antenna Lecture Notes   Asst. Prof. Dr. Özgür Tamer
    Antenna Arrays




Antenna Lecture Notes   Asst. Prof. Dr. Özgür Tamer
    Frequency Allocation




Antenna Lecture Notes      Asst. Prof. Dr. Özgür Tamer
    Propagation Loss




Antenna Lecture Notes   Asst. Prof. Dr. Özgür Tamer
    Poynting Theorem
    • Poynting vector is represented by P and represents the
      density and the direction of the EM power flow.


       Where E and H denote the Electric and the Magnetic Field
       Intensities

    • The average power flow is given by:



       Positive if there is outflow or negative if there is inflow
Antenna Lecture Notes                                  Asst. Prof. Dr. Özgür Tamer
    Poynting Theorem

    • Radiated power is the average power radiated by
      the antenna:




Antenna Lecture Notes                       Asst. Prof. Dr. Özgür Tamer
    Theory of Radiation

    • Radiation is produced by a time varying current
      element
    • Current element is a filament of length l and
    current I ( IΔl ), (A x m)
    • The field radiated by any antenna can be analyzed
      using the superposition principle after decomposing
      the antenna into current elements.




Antenna Lecture Notes                        Asst. Prof. Dr. Özgür Tamer
    Theory of Radiation

    From Maxwell’s Equations:


    By taking curl the wave equation can be obtained




Antenna Lecture Notes                             Asst. Prof. Dr. Özgür Tamer
    Theory of Radiation




Antenna Lecture Notes     Asst. Prof. Dr. Özgür Tamer
    Theory of Radiation

    The field due to the currents can be determined by
     integration of the currents over the surface.




Antenna Lecture Notes                        Asst. Prof. Dr. Özgür Tamer
    Theory of Radiation




Antenna Lecture Notes     Asst. Prof. Dr. Özgür Tamer
    Theory of Radiation

    For antenna problems the following process is used:
    1. find the current on the antenna surface, S,
    2. remove the antenna materials and assume that the
         currents are suspended in the unbounded medium,
    3. apply the radiation integrals.




Antenna Lecture Notes                         Asst. Prof. Dr. Özgür Tamer

								
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