EHF/SHF antennas with shaped dual-reflectors

The shaping of the subreflectors is done to improve the illumination, spillover, and blockage efficiencies, while the shaping of the main reflector is done to obtain uniform phase distribution. There are two different shaped subreflectors in each system, with one being a dichroic which is attached to the other solid subreflector. The dichroic is a trislot array resonant at Q-band to allow Q-band signal to pass through and reflect K-band. The whole subreflector assembly is rotated with respect to the solid subreflector axis to achieve conical scan at K-band for the tracking of the satellite. A computer program which is the extension of the second version of the Numerical Electromagnetic Code Reflector Antenna Code has been used to analyze these shaped dual-reflector antennas. A geometrical theory of diffraction approach is used to calculate the subreflector pattern and the far-out sidelobes of the main reflector. Aperture integration is used to obtain the main beam and near-in sidelobes.<>