Efficient technique for determining beam scanning characteristics of axisymmetric paraboloid reflectors

An efficient technique for the determination of the beam scanning parameters (viz. the direction of maximum gain, the number of beamwidths scanned, the scan limits with gain loss etc.) for axisymmetric paraboloid reflectors with defocused feed is presented. This technique can be used regardless of the respective range of focal-length-to-diameter ratio (F/D), the depth of illumination taper and the size of reflector. Representative numerical results obtained by using this technique are presented and discussed. These results also indicate the following: the direction of maximum gain deviates from both the direction of minimum pathlength variation and the direction of feed-displacement squint angle for the low F/D value; the orientation of directional feed to achieve maximum gain is complicated for the low F/D value with the large lateral feed displacement but approaches the point towards the vertex of reflector for the large F/D value; and the scan limits are substantially inferior to those inferred from earlier analyses, especially for the case of large F/D value and large feed lateral displacement