1 / 12

Antenna Primer

Antenna Primer. Wang Ng. References. Balanis; Antenna Theory Collin; Antennas and Radiowave Propagation. What is an antenna?. The American Heritage Dictionary: A metallic apparatus for sending and receiving electromagnetic waves.

Samuel
Télécharger la présentation

Antenna Primer

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Antenna Primer Wang Ng

  2. References • Balanis; Antenna Theory • Collin; Antennas and Radiowave Propagation

  3. What is an antenna? • The American Heritage Dictionary: A metallic apparatus for sending and receiving electromagnetic waves. • Webster’s Dictionary: A usually metallic device (as a rod or wire) for radiating or receiving radio waves. • Balanis; Antenna Theory: An antenna is a transitional structure between free-space and a guiding structure. • Assumption: Lossless antennas

  4. Types of Antennas • Wire antennas • Aperture antennas • Array antennas • Reflector antennas • Lens antennas • Patch antennas

  5. Radiation Mechanism

  6. Basic Antenna Parameters • Radiation pattern: The relative distribution of radiated power as a function of direction in space – an (hypothetical) isotropic antenna radiates equally in all directions. • Gain G : The ratio of the radiated power in the maximum direction to the radiated power of an isotropic antenna. The gain of an antenna represents the ability to focus its beam in a particular direction – an isotropic antenna has a gain of 0 dB.

  7. Basic Antenna Parameters • Radiation Resistance RA: The equivalent resistance which would dissipate the same amount of power as the antenna radiates. • Input impedance ZA : The ratio of the voltage to the current at the antenna terminals (Thevenin equivalent circuit). • Polarization: The direction of the E-field.

  8. Basic Antenna Parameters • Beamwidth: The angle between the two directions in which the radiated power is half of the maximum value of the beam. • Bandwidth: Half-power frequency band. • Antenna efficiency: e = Prad/ Pin • Effective aperture: It describes the effectiveness of an antenna in the receiving mode. It is defined as the ratio of the power delivered to the load to the incident power density.

  9. Friis Transmission Equation • For polarization matched antennas aligned for maximum directional radiation and reception, the ratio of the transmitted and received power is: Space Loss Factor

  10. Radiation Pattern of an Infinitesimal Dipole

  11. Radiation Pattern of a Thin Dipole

  12. Radiation Pattern of a Circular Loop

More Related