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Voltage standing wave ratio (VSWR) (pronounced "vizwar" [1][2]) is the ratio of maximum to minimum voltage on a transmission line . For example, a VSWR of 1.2 means a peak voltage 1.2 times the minimum voltage along that line, if the line is at least one half wavelength long. A SWR can be also defined as the ratio of the maximum amplitude to ...
A standing wave ratio meter, SWR meter, ISWR meter (current " I " SWR), or VSWR meter (voltage SWR) measures the standing wave ratio (SWR) in a transmission line. [a] The meter indirectly measures the degree of mismatch between a transmission line and its load (usually an antenna). Electronics technicians use it to adjust radio transmitters and ...
Antenna measurement techniques refers to the testing of antennas in order to ensure that the antenna meets specifications or simply to characterize it. Typical antenna parameters are gain, bandwidth, radiation pattern, beamwidth, polarization, impedance; These are imperative communicative means. The antenna pattern is the response of the ...
Radiation resistance is that part of an antenna 's feedpoint electrical resistance caused by the emission of radio waves from the antenna. [a][1][2] A radio transmitter applies a radio frequency alternating current to an antenna, which radiates the energy of the current as radio waves. Because the antenna is absorbing the energy it is radiating ...
Height above average terrain (HAAT), or (less popularly) effective height above average terrain (EHAAT), is the vertical position of an antenna site above the surrounding landscape. HAAT is used extensively in FM radio and television , as it is more important than effective radiated power (ERP) in determining the range of broadcasts ( VHF and ...
The electrical length of an antenna, like a transmission line, is its length in wavelengths of the current on the antenna at the operating frequency. [ 1 ] [ 12 ] [ 13 ] [ 4 ] : p.91–104 An antenna's resonant frequency , radiation pattern , and driving point impedance depend not on its physical length but on its electrical length. [ 14 ]
The J-pole antenna is an end-fed omnidirectional half-wave antenna that is matched to the feedline by a shorted quarter-wave parallel transmission line stub. [5] [1] [6] For a transmitting antenna to operate efficiently, absorbing all the power provided by its feedline, the antenna must be impedance matched to the line; it must have a resistance equal to the feedline's characteristic impedance.
In radio engineering, an antenna (American English) or aerial (British English) is an electronic device that converts an alternating electric current into radio waves (transmitting), or radio waves into an electric current (receiving). [1][2] It is the interface between radio waves propagating through space and electric currents moving in metal ...