File:CH 14.png

Comparative pictures of the original and second CHILL radar antennas. The horn support struts on the original antenna passed through holes in the reflector. This placed them closer to the boresight axis where they were illuminated by higher intensity radiation from the horn. Scattering from the support struts increased the antenna’s side lobe levels. (To reduce side lobe levels, the original antenna was rotated 45° around the boresight axis when the antenna was installed at Greeley. Compare to Fig. 3.) In the new antenna, the support strut mountings were moved outward to the rim of the reflector, and the reflector’s surface shape accuracy was also improved. The new antenna’s major design goal was improved dual polarization measurement capabilities.