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 flat-plate dual band array antenna is described which comprises two flat plate arrays of single band antenna elements, each of which operates in a different frequency band. The two flat plate arrays are positioned one above the other, with areas in the upper flat plate array being removed in order that the antenna elements in the lower flat plate array can radiate through the upper flat plate array. The geometric arrangement of the antenna elements is such that distribution networks for the antenna elements can be accommodated in the limited space available. Dual band flat-plate array feeds for a reflector antenna are also described. These use at least two flat-plate arrays that are positioned one above the other. Again regions in the upper flat-plate array are removed to allow the lower flat-plate to operate through the upper one.

Abstract: A flat-plate dual band array antenna is described which comprises two flat plate arrays of single band antenna elements, each of which operates in a different frequency band. The two flat plate arrays are positioned one above the other, with areas in the upper flat plate array being removed in order that the antenna elements in the lower flat plate array can radiate through the upper flat plate array. The geometric arrangement of the antenna elements is such that distribution networks for the antenna elements can be accommodated in the limited space available. Dual band flat-plate array feeds for a reflector antenna are also described. These use at least two flat-plate arrays that are positioned one above the other. Again regions in the upper flat-plate array are removed to allow the lower flat-plate to operate through the upper one.

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.