The SAT Collars..
These have the same RFID/GPS tracker/Logger and 2ms beep generator in addition to the IRIDIUM SAT Modem.
The Non SAT collars use a 40mm wide strap, while the SAT modem collars use a 50mm wide strap – the modem uses quite a bit of power, and to obtain a 2 year collar life wi need to fit 3 D cell Lithium batteries ( 3x19AH). to accommodate this width, and the width of the modem, the collars needs to be 65mm wide, but that would not work, so I use 50mm width strap, and made special encapsulation molds that will create a bulge of encapsulation in the correct spots.
The molds are made from fibreglass, using a shapes plug made from superwood, sealed with epoxy resin, waxed, and glassed. These then fit, like a clam shell, around the strap, and the encapsulation is injected within.
The Plug for the collar top, housing the SAT modem and GPS tracker

The Plug coated with GEL Coat.
Glass fibre cloth is layered over this in many layers, and then placed in a vacuum bag and vacuum pulled.
This pulls the glass up against the plug till cured.

When Cured, the breather cloth, bag and waste is removed, the mold pulled from the plug, and the second clam half made.

Both clam halves. This will house the modem and GS tracker

Similarly the battery end of the collar has its molds made.

Both Clam Shells in place.

The SAT modem and GPS tracker – about 90mm long, 45mm wide and 20mm tall.

Here is a collar after more than two years, fitted to a Hyena, and removed after a monumental territorial fight between it and another male..
The strapping is extremely tough, does not tear easily at all, is 4mm thick, polyurethane and Aramid fibre, and the Hyena bite put 7 teeth THROUGH on one side and 5 on the other.. I suspect the collar saved the Bitten's life..
The electronics were still intact. but the combined antenna/battery supply cables were ripped out.
Upon recovery of the collar I was able to break open the encapsulation and remove the tracker, re-power it and extract the last available data logs from it – The tracker is wrapped in teflon tape prior to encapsulation specifically so that the resin does not touch the electronics, rendering it unrecoverable.

See how the M4 bolt below is also bent…


I hope this was not too 'un-engineering'..
Joe