Can I embed these antennas in epoxy?

[DTJ]

I'm looking at an application where small patch or dome antennas are mounted in public locations exposed to potential vandalism.


One thought was to pot these in some grey epoxy so they blend in with the galvanised steel housing they are mounted to so as to not attract attention.
The cabling is all concealed its just the dome we want to protect.

The patch / dome antennas (4G, GPS etc) will be different depending on the location and could be anything from 400MHz through to 2100MHz.


I guess its a broad question but how much will a generic potting epoxy degrade the signal?


An alternative might be to see what protective  covers are available. I've not been able to find any.
I've seen some fitted on power infrastructure so they do exist.


Any and all ideas welcome!

[Mechatrommer]

you put anything near antenna it will change characteristic hence performance, let alone penetration strength. so you need a tool to be sure.

[DTJ]

Ok, thanks for the replies.

I'm a plug'n play as far as RF goes so playing around with antenna tuning is not going to happen!

I guess I'll need to either just try it or try to find off the shelf covers.

Are there particular plastics that are used for radomes that have a minimal effect on the signal?

[hagster]

From a quick search Epoxy has a permitivity of about 3.6. That will definatly make a difference if very close to most antenna.

[DTJ]

Thanks Hagster. I did a quick check on a polyurethane compound, it had a permittivity of 4 so I guess that is not good either.

Am I correct in assuming these values are relative permittivites in relation to the permittivity of free space?
So the closer the value to 1, the less effect it would have on the antenna?

[mjs]

Right, 1 is vacuum/air. PE foam is much closer to 1 and can be used to reduce close-field losses and antenna detuning. But even then you probably need to tune the antenna.

[Beamin]

Right, 1 is vacuum/air. PE foam is much closer to 1 and can be used to reduce close-field losses and antenna detuning. But even then you probably need to tune the antenna.

That was my suggestion then paint over it minding the type of paint. While foam is not vandal proof if it looks like what ever it is blending into people will have no reason to try and mess with it. Out of sight out of mind.

Where I live people will steal anything metal even if it's bolted to the ground they will steal the nuts too!