Hydrophobic feed window

• US 20070126652A1
• Filed: 12/02/2005
• Published: 06/07/2007
• Est. Priority Date: 12/02/2005
• Status: Active Grant

• Current Assignee: Raven Antenna Systems, Inc. (Satellite Acquisition Corporation)
• Original Assignee: Andrew Corporation (CommScope Holding Company, Inc.)
• Inventors: Wolfenden, Neil, Batson, Rosalind
• Granted Patent: US 7,375,698 B2
• Time in Patent Office: Days
• US Class Current: 343/872
• CPC Class Codes: H01Q 1/42 Housings not intimately mechanically associated with radiating elements, e.g. radome

Abstract

A feed window for a low noise block converter feedhorn incorporated into a microwave-range antenna assembly is formed from a thermoplastic polymer composition containing a hydroscopic-effective amount of a high molecular weight siloxane.

Claims

1. A feed window for a low noise block converter feedhorn incorporated into a microwave-range antenna assembly, said feed window formed from a thermoplastic polymer composition containing a hydroscopic-effective amount of a high molecular weight siloxane.

2. A feed window of claim 1 wherein the siloxane is an ultra-high molecular weight polydialkylsiloxane.

3. A feed window of claim 1 wherein the siloxane is an ultra-high molecular weight polydimethylsiloxane.

4. A feed window of claim 1 wherein the thermoplastic polymer is a polyolefin of monomer units containing 2 to 8 carbon atoms.

5. A feed window of claim 1 wherein the thermoplastic polymer is a propylene polymer.

6. A feed window of claim 5 wherein the propylene polymer contains up to 20 wt. % copolymerized ethylene monomer.

7. A feed window of claim 1 wherein the hydroscopic-effective amount of siloxane is between 0.1 and 3 wt. % of the polymer composition.

8. A feed window of claim 1 wherein the hydroscopic-effective amount of siloxane is between 0.25 and 2 wt. % of the polymer composition.

9. A feed window of claim 5 wherein siloxane is added to the propylene polymer as a masterbatch of siloxane and a polypropylene.

10. A feed window of claim 3 wherein the siloxane has a viscosity of 100,000 to 200,000 cm²/sec.

11. A feed window of claim 3 formed from a propylene polymer composition containing an ultra-high molecular weight polydimethylsiloxane having a viscosity of 150,000 to 200,000 cm²/sec in which the siloxane is incorporated into the propylene polymer composition as a 50:

50 masterbatch of siloxane and polypropylene and wherein such masterbatch is incorporated at a level of 0.25 to 2 wt. % in the propylene polymer.

12. A feed window of claim 11 in which the propylene polymer is a block copolymer containing up to 20 wt. % ethylene.

13. A microwave-range antenna assembly comprising a low noise block converter feedhorn fixed within antenna dish covered by a feed window formed from a thermoplastic polymer containing a hydroscopic-effective amount of a high molecular weight polydialkylsiloxane.

14. An assembly of claim 13 in which the feed window is formed from a propylene polymer composition containing 0.1 to 3 wt. % of an ultra-high molecular weight siloxane having a viscosity of 100,000 to 200,000 cm²/sec.

15. An assembly of claim 14 in which the propylene polymer composition contains 0.25 to 2 wt. % siloxane having a viscosity of 150,000 to 200,000 cm²/sec.

16. An assembly of claim 15 in which the siloxane is added to the propylene polymer as a masterbatch of siloxane and a polyolefin.

17. A method to protect a low noise block converter feedhorn from weather comprising covering the feedhorn with a feed window formed from a thermoplastic polymer containing a hydroscopic-effective amount of a high molecular weight polydialkylsiloxane.

18. A method of claim 17 in which the feed window is formed from a propylene polymer composition containing 0.1 to 3 wt. % of an ultra-high molecular weight polydimethylsiloxane having a viscosity of 100,000 to 200,000 cm²/sec.

19. A method of claim 18 in which the propylene polymer is a block copolymer of propylene and ethylene.

20. A method of claim 19 in which the propylene polymer composition contains 0.25 to 2 wt. % siloxane.