I don’t know very much about the T5577 so somebody else will have to help you out with that.
A Easy with a DIY antenna you can make for quite cheap (if you are handy with that stuff) would probably be a good substitute for the ProxLF antenna.
@amal by the way there seems to be untapped market for the easy LF antenna there. Better add it to the list of awesome things to (maybe) make happen (someday) 
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