Antenna Radome

[Redron]

I am interested in building a small trash can lid size radome antenna and was wondering if it could be made with polyester resin and a roven fiberglass material? If anyone could point me in the direction of some literature, or a cheaper way then say Quartz or a oven cured epoxy. Will a room temp epoxy work? HELP! I own a small fiberglass shop and understand how most composites work. Thank You, Ron

 

[Higgler]

Anything works at low frequency, at higher frequency if you have a small bandwidth, you need to make the radome 1/2 wave thick. I've done alot of radome stuff, khiggler at yahoo dot com.

kevin

 

[Redron]

Kevin,
Thanks for talking to me, I have never built one before and the guy that wants it is not very knowledgeable. So here is what I was thinking, the part is 24 1/2 in diameter in the mold I thought clear gelcoat ( Could you use a colored gel? ) with a layer of 6oz S fiberglass w/ epoxy on that, then the antenna array but I'm not what should come next, I'm pretty sure it's low frequency (I'll know today) I was thinking like a couple layers of a heavy fiberglass material, I think that you want no waves coming into the shape, all out the face Right? Man thanks for any info you can help me wih. Ron

 

[Higgler]

The frequency is key. Can you mention the application?
You say 24.5 inch diameter, does that mean the shape is round and half of a sphere?

The shape will matter alot if the frequency is high, and won't matter at all if the frequency is low. But if he's already given you a shape (round) and didn't tell you what thickness to build the walls, his electronics is either low frequency or he doesn't understand radomes. What thickness are you plannin? 0.1" 0.2" ?

One way to see how lossy something is is put a piece in a microwave oven for ??10 to 60 seconds and see how much it heats up. That's only a crude way, if you have a choice of two resin's and other materials, put them in the microwave oven, in the same location and same size pieces and heat them for the same amount of time. At least if you do that and tell your customer you did an absorption loss test to use the lowest loss materials in his radome, he'll be more impressed at your diligence and come back to you with future work. Most Engineers will return to the same people to build things if they do a good job, we really appreciate good consistent workers that we don't have to worry about.

Prototype antenna radomes are often fairly expensive, multi thousands of dollars.

Kevin

 

[Redron]

Like I said it's 24.5 inches in diameter sides are 1 3/4 dome is 3 inches in center and yes it's low frequency. So would it matter if I put color in gel? He doesn't seem to care about the wall thickness I was planning 1/4 inch with a aluminum plate for a base. Was thinking a core material for the backing behind the antenna array so it didn't leak into the inside of dome, but then he said he needed a hole to solder to the array, that must not be an issue to him either??? Unless he seals it later, not sure just going to give him what he asks for. But thanks for the microwave absorption test. I like that. Thanks, Ron

 

[Higgler]

If it's low frequency, it won't matter about the coloring.

Can you send a sketch and mention the frequency?

If he is asking for a full environmental cover, adding a metal base to it could totally change the antenna, no matter what frequency it is. Ask him specifically if it's ok to make a metal base for this antenna?

A hole to solder to the array in your base is a strange phrase, normally an antenna has a connector or cable coming out the back of it.

I'd guess he bought something and wants an environmental cover from you and he has no idea what may affect it's performance. Antennas can be very sensitive if you put the wrong material around it. I am an antenna engineer, I'm not a genius but I am old (50) and experienced.

Charge him extra if you stop him from doing something wrong. Give hime two bills, one for the part, one for the research.

good luck,

kch