What is the best material for cover sheet

[bkd]

Hi
I design radar antenna at 1.52 Ghz. I intend to use cover sheet for dipole element to avoid weather.
Can you give me a suggestion for choosing the material for cover sheet.
I find some information as polycarbonate, ABS,.. .
As i find the PC have dielectric constant 2.9 . And how about ABS or other. Does it change the frequency respond and radiation pattern of the dipole antenna??. When simulation must we take care of this sheet??..Anything else
Please tell me some of your experience in this field
Thank you very much

 

[sergio mariotti]

The most radio-transparent material is the GoreTex radome fabric (woven). Er is close to 1.5, thickness is so small compared to Your wavelenght to be considered non-changing the pattern direction.

 

[flatulent]

Another property to take into account is deterioration from the UV radiation of the sun.