GTD, physical optics, and jacobi-bessel diffraction analysis of beam waveguide elipsoids

For certain applications of beam waveguides to large ground system antennas, the use of ellipsoid pairs in place of more conventional paraboloid pairs is appropriate. For example, in the application illustrated in Figure 1, the feed and maser system is rotated in azimuth with the antenna. In this case, the beam waveguide does not go directly to the axis of the main reflector but bypasses some in-place heavy machinery along this axis. In this configuration, ellipsoid pairs are more suitable because their convergent ray characteristic allows for a lower loss transmission and also because the three independent focii can be aligned in accordance with the rules discovered by Mizusawa and Kitsuregawa.l Thus aligned, the ellipsoid pair perfectly images the feed pattern according to geometrical optics (see Figure 2).