Definitions for "Sidelobe"
Keywords:  lobe, antenna, weisstein, dbi, airy
The portion of an antenna response pattern which is not contained in the main beam. (See Q-channel antenna)
Off-axis response of an antenna.
The portion of an antenna response pattern which is not contained in the main beam. For an ideal beam, this will be the lobes of the Airy pattern, but can be considerably more complicated for real antennas. For a dirty beam (synthesized beam), sample space consists of a finite number of points (the source cannot be sampled at exactly its spatial harmonics), so sidelobes are introduced. These can be reduced by weighting (tapering) the data. Hanning and Gaussian tapers are sometimes used. Weighting the data, however, results in loss of resolution and cannot completely remove the sidelobes. Sidelobes are also produced by the sharp edge which is present in the (u, v) sampling as a result of a finite baseline length.- from Eric Weisstein's World of Physics