My GTD Wireless Microphone system uses TNC connectors. I don't know if all of them use this same connector. If yours is TNC, then the instructions below will work. If yours uses a different type of connector, the concept works, but you'll need to find the right connector for your system.
First, you need a blank rack panel (like the one below)...
http://www.markertek.com/product/nxlp-1/nxlp-1-empty-patch-panel-for-8-neutrik-d-type-connectors
... then you need a blank plate (like the one below)...
http://www.markertek.com/product/dba/neutrik-dba-bl-d-series-blank-plate
... then you need to drill a hole in the blank plate to fit the inline splicer (like the one below)...
http://www.markertek.com/product/27-9067/tnc-inline-splice
... The inline splicer should come with the nuts to attach it to the blank plate. Screw the blank plate to the rack panel. Then you connect the cable (like the one below), from the rear antenna terminal on your GTD microphone system to the inline splicer.
http://www.markertek.com/product/20...0-type-rp-tnc-male-to-n-type-female-cable-2ft
... Finally, connect the rack panel to your rack and the antenna to the inline splicer on the rack panel.
Just to be clear, I intentionally bought a system with the antennas on the front so I would not have to take the steps listed above. I bought my system online and did not notice the location of the squelch knob. For me to mount a rear antenna system in my rack would have cost about $60 for two antennas because I already had extra slots in the rear panel on my rack. Here's a pic of the back of my rack...