Antenna Measurement Techniques (1)

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Antenna Measurement Techniques (1) [复制链接]

Part I: Theory & Principles

Antennas are devices for transmitting and/or receiving electromagnetic energy
through a medium or media at a given frequency band. Most antennas are used
to transmit and receive electromagnetic waves that carry information over a distance away from each others.Antennas can appear in a great variety of
forms depending on their applications

Theory

Fundamental Principles of the antennas are described by the following four mathematical Equations often referred to as Maxwell’s Equations

Antenna Types 

•     Resonant Antennas                                                   

        Dipoles, Yagi-Uda arrays
        Loops
        Micro-strip Patches

•    Travelling Wave Antennas

         Horns; Log-period antennas
         Rhombic antennas

• Quasi-optical Beam Forming Antennas

          Parabolic reflector antenna, Array antenna

Antenna Polarization

Linear polarization: The electric field always lies on a line within the period (commonly referred)

Circular Polarization: The electric field uniformly changes its direction 360 degrees with a constant magnitude during a time-varying period (CW, CCW)

Elliptical Polarization: The electric field uniforml changes its direction and magnitude during a time varying period (generic antenna properties) A term to define the electric field orientation within a time-variation period of the electromagnetic wave