CONTROLLED ILLUMINATION DIELECTRIC CONE RADIATOR FOR REFLECTOR ANTENNA
A dielectric cone radiator sub-reflector assembly for a reflector antenna with a waveguide supported sub-reflector is provided as a unitary dielectric block with a sub-reflector at a distal end. A waveguide transition portion of the dielectric block is dimensioned for coupling to an end of the waveguide. A dielectric radiator portion is provided between the waveguide transition portion and a sub-reflector support portion. An outer diameter of the dielectric radiator portion is provided with a plurality of radial inward grooves and a minimum diameter of the dielectric radiator portion is greater than ⅗ of a sub-reflector diameter of the sub-reflector support surface.
1 . A cone radiator sub-reflector assembly for a reflector antenna with a waveguide supported sub-reflector, comprising:
a unitary dielectric block;
a sub-reflector provided at a distal end of the dielectric block;
a waveguide transition portion of the dielectric block dimensioned for coupling to an end of the waveguide;
a sub-reflector support portion of the dielectric block; and
a dielectric radiator portion between the waveguide transition portion and the sub-reflector support portion; an outer diameter of the dielectric radiator portion provided with a plurality of radial inward grooves; a minimum diameter of the dielectric radiator portion greater than ⅗ of a sub-reflector diameter of the sub-reflector support surface.
2 . The assembly of claim 1 , wherein the sub-reflector is a metal coating upon the distal end of the dielectric block.
3 . The assembly of claim 1 , wherein the sub-reflector is a separate metal portion seated upon the distal end of the dielectric block.
4 . The assembly of claim 1 , wherein the sub-reflector diameter is 2.5 wavelengths or more of a desired operating frequency.
5 . The assembly of claim 1 , wherein the waveguide transition portion is dimensioned for insertion into the end of the waveguide until the end of the waveguide abuts a shoulder of the waveguide transition portion.
6 . The assembly of claim 1 , wherein the sub-reflector support portion extends from a distal groove of the dielectric radiator portion as an angled distal sidewall of the distal groove.
7 . The assembly of claim 6 , wherein the angled distal sidewall is generally parallel to a longitudinally adjacent portion of the distal end.
8 . The assembly of claim 1 , wherein the distal end is provided with a proximal conical surface which transitions to a distal conical surface; the distal conical surface provided with a lower angle with respect to a longitudinal axis of the assembly than the proximal conical surface.
9 . The assembly of claim 8 , wherein the sub-reflector support portion extends from a distal groove of the dielectric radiator portion as an angled distal sidewall of the distal groove; the angled distal sidewall generally parallel to the distal conical surface.
10 . The assembly of claim 1 , wherein a periphery of the distal end is normal to a longitudinal axis of the assembly.
11 . The assembly of claim 1 , wherein the plurality of grooves is two grooves.
12 . The assembly of claim 1 , wherein a bottom width of the plurality of grooves decreases towards the distal end.
13 . The assembly of claim 1 , wherein a longitudinal distance between the end of the waveguide and the distal end at the sub-reflector periphery is at least 0.75 wavelengths of a desired operating frequency.
14 . A method for forming a sub-reflector for a deep dish reflector antenna, comprising the steps of:
forming a dielectric block; and
coupling a sub-reflector to a distal end of the dielectric block;
a waveguide transition portion of the dielectric block dimensioned for coupling to an end of the waveguide;
a sub-reflector support portion of the dielectric block; and
a dielectric radiator portion between the waveguide transition portion and the sub-reflector support portion; an outer diameter of the dielectric radiator portion provided with a plurality of radial inward grooves; a minimum diameter of the dielectric radiator portion greater than ⅗ of a sub-reflector diameter of the sub-reflector support surface.
15 . The method of claim 14 , wherein the sub-reflector diameter is 2.5 wavelengths or more of a desired operating frequency.
16 . The method of claim 14 , wherein the sub-reflector is coupled to the distal end of the dielectric block by coating the distal end with an RF reflective material.
17 . The method of claim 14 , wherein the sub-reflector is coupled to the distal end of the dielectric block by seating a metallic disc against the distal end.
18 . The method of claim 14 , wherein the forming of the dielectric block includes injection molding the dielectric block.
19 . The method of claim 14 , wherein the forming of the dielectric block includes machining the dielectric block.
20 . The method of claim 14 , wherein a longitudinal distance between the end of the waveguide and the distal end at the sub-reflector periphery is at least 0.75 wavelengths of a desired operating frequency.