11/14/2022 0 Comments Microvolts to dbmThe dipole concentrates the energy in certain directions, so that the radiation in those directions is greater than the radiation from an isotropic source with the same input power. A half-wavelength dipole antenna has a gain of 2.15 dB greater than an isotropic antenna. Figure 1 Half wave dipole vs isotropic antennaĪn antenna which can be easily built is a half-wavelength dipole. Even though this type of an antenna cannot actually be constructed, the use of the concept provides a uniform standard against which the performance of all manufactured antennas can be calibrated and compared. This is a theoretical antenna that radiates the same level of energy in all directions when power is applied to the antenna. The simplest antenna is an isotropic radiator. Broadcast antenna manufacturers commonly refer to a multiplier gain where the antenna input power is multiplied by this gain to yield the effective radiated power. The land mobile industry has almost universally expressed antenna gain as dBd (referenced to a half-wave dipole rather than isotropic.) When a manufacturer lists a gain as dB, you may generally assume that the referenced gain is dBd. The microwave industry has universally established the convention of reporting antenna gain in dBi (referenced to isotropic). Antenna gain stated in dB is referenced to either isotropic or a half-wave dipole. Gain may be expressed as either a power multiplier or in dB. Therefore, let us first consider antenna gain. While field strength at any location is independent of antenna gain, received voltage at the receiver is not. This FAQ discusses units of gain and field intensity and explains how to convert between some of these units when appropriate. There is a great deal of confusion when engineers, technicians, and equipment salespersons talk about units of antenna gain and field strength. Added on: July 30, 2013, in: RF Engineering Articles
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