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The bandwidth characteristics of a resonant antenna element can be characterized according to its Q where the resistance involved is the radiation resistance, which represents the emission of energy from the resonant antenna to free space. The Q of a narrow band antenna can be as high as 15.
Radio propagation is the behavior of radio waves as they travel, or are propagated, from one point to another in vacuum, or into various parts of the atmosphere. [1]: 26‑1 As a form of electromagnetic radiation, like light waves, radio waves are affected by the phenomena of reflection, refraction, diffraction, absorption, polarization, and scattering. [2]
The vertical plane is used to plot an antenna's relative field strength perpendicular to the ground (which directly affects a station's coverage area) on a polar graph. Normally, the maximum of 1.000 or 0 dB is at the side (unless there is beam tilt), which is labeled 0°, to 90° at the top and −90° at the bottom.
Typical antenna parameters are gain, bandwidth, radiation pattern, beamwidth, polarization, impedance; These are imperative communicative means. The antenna pattern is the response of the antenna to a plane wave incident from a given direction or the relative power density of the wave transmitted by the antenna in a given direction. For a ...
The second antenna is a reference antenna, which points rigidly at the first antenna. Each antenna is alternately connected to a transmitter having a particular source impedance, and a receiver having the same input impedance (the impedance may differ between the two antennas).
In antenna engineering, sidelobes are the lobes (local maxima) of the far field radiation pattern of an antenna or other radiation source, that are not the main lobe.. The radiation pattern of most antennas shows a pattern of "lobes" at various angles, directions where the radiated signal strength reaches a maximum, separated by "nulls", angles at which the radiated signal strength falls to zero.
The quarter-wave monopole, the most compact resonant antenna, may be the most widely used antenna in the world. The five-eighth wave monopole – length 0.625 λ, or 5 / 8 of a wavelength – is also popular, since at that length monopoles direct the greatest proportion of their radiated power horizontally, hence the best use of ...
A lens antenna is made from a layer of dielectric, or a metal screen, or multiple waveguide structure of varying thickness, mounted in front of a feed antenna. The waveguide / screen / dialectric refracts the radio waves, focusing them on the feed antenna, similar to a focusing lens placed in front of a flashlight. Dielectric resonator