MINIMIZATION OF THE PLANE-WAVE SCATTERING CONTRIBUTION OF INVERTED-Y STRUT TRIPODS TO THE NOISE TEMPERATURE OF REFLECTOR ANTENNAS

This work is concerned with determining the metallic strut cross secti on of inverted-Y tripods to minimize the plane-wave scattering contrib ution to the noise temperature of ground-station reflector antennas an d radio telescopes. This is accomplished by numerically optimizing the cross section for minimum ground-noise pickup over the antenna elevat ion-angle operation range, Advantage is taken of the fact that althoug h the struts' cross-section perimeter can be comparable to the operati on wavelength, their electrical lengths are usually long, This allows the struts' scattering characteristics to be determined by solving sta ndard two-dimensional field integral equations. This work concentrates on the top strut of an inverted-Y configuration since it is responsib le for the dominant ground noise pickup associated with the plane-wave scattering, Numerical simulations are presented to substantiate this fact and a simple and convenient broadband closed-form representation for the minimum-noise top-strut cross section is derived and tested.