 # Essay On Linear Polarization

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To fully understand the technical terms and relevant topics related to the project, a literature review was done. In this section, a brief summary of it is presented. Antenna Basics Polarization The polarization of an antenna is described by the time-varying direction of an electromagnetic wave and the relative magnitude of the vector of the electric field. There are three kinds of polarization: linear polarization, circular polarization and elliptical polarization. Linear polarized electric field can possess both horizontal and vertical orientation. Circular polarization has two linearly polarized electric fields with the same magnitude but the phase difference is 90 degree. While, the elliptical polarization has two different magnitude…show more content…
The impedance at the input terminal of the antenna is the area of interest. The input impedance usually depends on frequency. However there are other factors that will affect the input impedance of an antenna, such as its geometry, method of excitation, and the proximity to surrounding environment. Gain Gain of the antenna is the ratio of the power gained in a specific direction of peak radiation to the radiation of an isotropic source. Antenna gain is usually referred as relative gain. It is the maximum power gain density in a given direction with reference to another antenna with known gain in the same direction. If there is no direction indicated, the antenna gain will peak amplitude of the gain value. Antenna’s gain is related to antenna’s directivity and efficiency. For ideal case, the directivity of an antenna equals to 1, indicating no loss. However, in real situation, antenna’s gain is less than directivity. Directivity Directivity relates radiation intensity in a given direction in terms of the average radiation intensity in all directions. D(θ,∅)=U(θ,∅)/U_av =4π U(θ,∅)/P_rad Where D(θ,∅) is the directivity of the antenna U(θ,∅) is the radiation intensity in a given direction (W/unit solid angle) Uav is the average radiation intensity over all directions (W/unit solid