Phased array design is, however, sometimes useful for beamsteering, or for sidelobe mitigation, but making these compromises necessarily reduces directivity.
42.
The directivity is shown to be a function only of the source size and shape, not of the specific type of transducer used.
43.
The reference antenna is usually the theoretical perfect isotropic radiator, which radiates uniformly in all directions and hence has a directivity of 1.
44.
As with directivity, when the gain G of an antenna is given independently of direction it refers to its maximum gain in any direction.
45.
As a consequence of their directivity, directional antennas also send less ( and receive less ) signal from directions other than the main beam.
46.
In Beverages longer than two wavelengths, directivity does not increase because the currents in the antenna cannot remain in phase with the radio wave.
47.
Side lobe levels can be reduced by tapering the edges of the aperture distribution ( changing from uniformity ) at the expense of reduced directivity.
48.
Even though an isotropic antenna cannot exist in practice, it is used as a base of comparison to calculate the directivity of actual antennas.
49.
A loudspeaker with a high degree of directivity ( narrow dispersion pattern ) can be said to have a high " Q ".
50.
For industrial noise map production, the most important thing is the description of noise sources : sound power levels, directivity, working periods.
