Making radomes

[supplementfreak]

The company I work for is looking to make radomes. We are wondering what the best way, thermoforming and such, is to do this and what plastics are recommended for this. We currently get our radomes from outside our company but are looking to this as an inside expansion. Any info that can be provided would be very much appreciated.

 

[Pud]

Hi supplementfreak,

Much depends on your volumes and the part thickness/diameter ratio.

Small volumes will not warrant tooling expenditure for injection moulding, and large diameters combined with thin section will not be possible to mould. Injection moulding much cheaper of course as a process.

I have seen radomes vacuum formed and injection moulded (we used to make 300mm dia versions no problem at 2.5mm thick - 1.2m dia 2.5mm thick were vacuum formed.)

The material used was called "Styrosun" (not sure who makes it these days, they keep changing owners) - it's an impact modified styrene using EPDM rather than Butadiene rubber as the modifier and also has a good UV package in as well. It is available in extrusion grades (to make sheet for vacuum forming) and injection moulding grades. Colours easily too. Has good RF properties (low loss), although I have seen drawings for large radomes specifying polycarbonate (IMHO not a good choice, but at least literally bullet proof!)

I have no connection with the makers of Styrosun, but I have never come across anyone else who makes a similar product!

rgds


Harry

 

[supplementfreak]

Thank you very much for the info. We have been doing a lot of searching and that little bit was more helpful than the time we have spent elsewhere.

 

[patprimmer]

Are you happy with the current ones. What are they made of and by what process.

Regards

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[Pud]

Hi supplementfreak,

After posting last note have had a look in stores (junkroom!) and found we still have some 300mm dia radomes. If you would like me to send a sample please let me know. I have not checked thickness of ones we have though. (Used to make different thicknesses for different frequencies - come to think about it I might have that info somewhere filed away - watch this space!)

 

[supplementfreak]

If you can find that information it would be very helpful. And thanks again.

 

[Pud]

Hi Supplementfreak,

All I have been able to locate is that the 2.3mm thickness was for 38GHz.

All the others (for lower frequencies) were thicker than that - up to 4mm if I recall correctly. (Is it related to wavelength? - I'm sure the thickness was someting to do with reflections of the inner and outer faces of the radome). You may be able to derive a formula for it?

Rgds


Harry

 

[dwightdixon]

If you are satified with the outside provided products but just want the profit internalized to your company, just copy them, if they do not have a patent on the design and materials. They should have supplied the material on their spec sheet. My preferance would be BASF AAS what has acrylic rubber substituted for the Butidene. There are also a number of sheet suppliers which have ABS with a cap sheet of Acrylic for exterior usage. Could be vac formed but I do not know what the thicknesses available are. if in US, check in Modern Plastic Encylcopiedia. Thomas Register would be another place to look them up in US.

 

[Plastserv]

Most of what I have seen has been in an ASA material. Similar to ABS in properties, except that it has great UV resistance.