Abstract: A low-cost spherical reflector and a mechanically scanned antenna system utilizing such reflectors. The system employs one or more (substantially similar) primary spherical reflectors (each a truncated spherical surface), each having an associated moveable feed driven by a two-axis positioner mechanism that has few moving parts. The feed structure may preferably comprise a point source waveguide feed in combination with a shaped concave secondary reflector used in a Gregorian-like configuration to correct for spherical phase error. The positioner mechanism moves the waveguide feed and secondary reflector in tandem to shift the position of the far field beam direction in the sky. After phase correction by the secondary reflector, the resultant signal reflected from the primary aperture can simultaneously transmit and receive at two or more independent frequencies.

Abstract: A method and apparatus are provided performing near-field measurements on dish antenna, in particular large dish antenna, and for utilizing these measurements to realign dish panels. The antenna is tiltable about a pivot point on a mounting pedestal to any desired elevation angle. A substantially circular track is provided which is centered at and spaced a predetermined distance from the pivot point, the track preferably being adjustably mounted to a stiff circular arch. The antenna is rotatable in the azimuth direction, preferably by rotating the pedestal, and a scanning probe is provided which is mounted for control traversal on the circular track. The probe is utilized to perform near-field measurements on the antenna at selected azimuthal positions of the antenna and selected positions of the probe on the track. The probe may also be rotatable to at least two different polarizations.