Dish antenna having a self-supporting sub-reflector assembly

An antenna comprising:

• a main reflector having a focal region;
• a sub-reflector having an under-surface and a recess in the under-surface;
• a waveguide horn extending from the main reflector toward the focal region and having a distal end;
• a dielectric tube extending from the distal end of the waveguide horn and having a distal end insertable into the recess in the sub-reflector, said dielectric tube having a collar extended inward about its distal end;
• an insert insertable into the dielectric tube to seat against the collar of the dielectric tube, said insert having an under-surface;
• and
• a fastener securing the insert against the collar of dielectric tube within the recess of the sub-reflector, thereby securing the sub-reflector to the distal end of the dielectric tube, with the under-surface of the insert and the under-surface of the sub-reflector providing a substantially continuous reflective surface for the waveguide horn.