Lumberjack

How can I reinforce a copper coil antenna?

I'm using RFID antennas (copper coils) for some zoological research that tracks animal movement. The antennas consist of a copper coil (15 loops of 0.25mm diameter Cu wire), connected by its ends (soldered) to a length of coaxial cable that feeds into a data logger unit. I've reinforced the fork where coax meets coil with some marine epoxy glue. The coil itself is coated with liquid electrical tape. I'm having a problem, though, because where the stiff, glued section meets the more flexible part of the coil, the wires are able to bend back and forth, and I've had several antennas break. Does anyone have any clever ideas of how I could reinforce the coil to prevent the wires breaking, but still maintain some flexibility so that they don't cause discomfort to the animals? Thanks in advance! John Thanks Demondoppel. I should have made it a bit more clear.. The stem leading to the coil resides almost entirely inside the data logger case, and hasn't been a weak area. The breakages tend to occur on the coil itself (e.g. a semicircle snaps off), and I think this is because I also put a dot a glue at the sides of the loop, and these adhese to the animals' fur. This makes another rigid-flexible transition, meaning that the coil has a consistent point at which to bend back and forth, leading to snaping of the copper. Thanks for your advice though. Heat-shrink tubing won't work, because it's a coil. There's no way for me to thread the tubing over the coil, unless I was to thread each loop of the coil through the tubing as I made the loop... which doesn't seem practical. Thanks charcinders, I'll check it out. :)

Public Comments

1. you can try reinforcing the wires up to the coils with additional stress relief coils (springy stainless steel) ...like patch cords do for guitars or microphones. Coat them with heat shrink tubing to prevent any hair from being grabbed by the spring coils.
2. use a plasctic tube... like a straw but stronger silicone isnt going to be stronger than epoxy... I wasnt talking about shrink wrap... I was talking about a plastic hose or sometype of strength reinforcment. like a stiff plastic tube or something similar. who cares if its practical as long as it works...
3. How about using silicone instead of epoxy? Dow Corning 3140 is a good one.
4. Can you use a coil former? Then you could fix the co-ax onto the former which should improve things somewhat. Be aware that the coil can have any shape. Doesn't have to be round, it can be square, rectangular or anything. You could possibly make it in the form of a belt that wraps around some part.
5. How about wrapping the coil around a cardboard or plastic tube? Or even flexible plastic tubing. Then secure the fragile connections to the tube where it extends beyong the ends of the coil