Abstract: A dual band antenna is described which comprises a single band antenna surrounded by single band antenna elements. For example, the single band antenna may be a horn operating at a first frequency band and the single band antenna elements may be a flat plate array. In this case, the flat plate array contains an aperture through which the horn extends. The single band antenna and single band antenna elements are positioned such that a transmit and a receive antenna beam are created which have approximately equal phase centres and beamwidths. The single band antenna may also be an array of antenna elements, such as a flat plate array. Alternatively the single band antenna may be formed from dipole elements. As well as this the single band antenna elements may be dipole elements, flat-plate elements or any other suitable type of elements. The dual band antennas described may be used as feeds for reflector antennas or as antennas in their own right.

Abstract: A dual band antenna is described which comprises a single band antenna surrounded by single band antenna elements. For example, the single band antenna may be a horn operating at a first frequency band and the single band antenna elements may be a flat plate array. In this case, the flat plate array contains an aperture through which the horn extends. The single band antenna and single band antenna elements are positioned such that a transmit and a receive antenna beam are created which have approximately equal phase centers and beamwidths. The single band antenna may also be an array of antenna elements, such as a flat plate array. Alternatively the single band antenna may be formed from dipole elements. As well as this the single band antenna elements may be dipole elements, flat-plate elements or any other suitable type of elements. The dual band antennas described may be used as feeds for reflector antennas or as antennas in their own right.