isotropic radiator

Note that a true isotropic radiator does not exist in practice.

However a true isotropic radiator cannot be built, so in practice a different antenna is used.

At a distance, the sun is an isotropic radiator of electromagnetic radiation.

That ratio would be equal to G if the reference antenna were an isotropic radiator.

It radiates uniformly in all directions from a point source sometimes called an isotropic radiator.

Sometimes, the half-wave dipole is taken as a reference instead of the isotropic radiator.

The sun approximates an isotropic radiator of light.

Certain munitions such as flares and chaff have isotropic radiator properties.

An isotropic radiator is a theoretical perfect speaker exhibiting equal sound volume in all directions.

In ideal free space, the electric field strength produced by a transmitter with isotropic radiator is readily calculated.

The isotropic radiator is a purely theoretical antenna that radiates equally in all directions.

Isotropic radiators are used as reference radiators with which other sources are compared.

More often, gains are expressed relative to an isotropic radiator, which is an imaginary aerial that radiates equally in all directions.

Therefore in terms of the true gain (relative to an isotropic radiator) G, this figure for the gain is given by:

An isotropic radiator is a theoretical point source of electromagnetic or sound waves which radiates the same intensity of radiation in all directions.

The reference antenna is usually the theoretical perfect isotropic radiator which radiates uniformly in all directions and hence has a directivity of 1.

The Big Bang is another example of an isotropic radiator - the Cosmic Microwave Background.

Antenna gain is often quoted with respect to a hypothetical antenna that radiates equally in all directions, an isotropic radiator.

The EIRP is often stated in terms of decibels over a reference power emitted by an isotropic radiator with an equivalent signal strength.

The smallest directivity a radiator can have relative to an isotropic radiator, is a Hertzian Dipole, which has 1.76 dBi.

For the commonly utilized half-wave dipole, the particular formulation works out to the following, including its decibel equivalency, expressed as dBi (decibels referenced to isotropic radiator):

"dBi" is used rather than just "dB" to emphasize that this is the gain according to the basic definition, in which the antenna is compared to an isotropic radiator.

In common usage "omnidirectional" usually refers to all horizontal directions, typically with reduced performance in the direction of the sky or the ground (a truly isotropic radiator is not even possible).

As it is impossible to build an isotropic radiator, gain measurements expressed relative to a dipole are more practical when a reference dipole aerial is used for experimental measurements.

Most antennas' gains are measured with reference to an isotropic radiator, and are rated in dBi (decibels with respect to an isotropic radiator).