Antenna design guidelines for RDM630 125 kHz RFID reader

I have an RDM630 reader that comes with a little coil antenna. It seems to work alright, but for my application I believe I need a larger loop. I am looking for guidelines about designing a new loop.

What is the nominal design inductance of the standard loop?
How about the DC resistance?
What is the nominal peak-peak voltage on the antenna?

I have been trying to reverse-engineer the specs using loop-inductance-calculators and it appears to be something like 2.5 to 2.8 mH. But the DC resistance of my example is 5.8R and this does not jibe with the expected DC resistance of that much 34AWG copper wire. I am expecting something in the 22R range. My antenna is a little beat up and might have a short. On the other hand it does seem to work.

I have measured the peak-peak voltage on the antenna at about 45V and I have no idea if this is approximately in spec or not.

My project involves creating an approx 170mm square rectangular antenna that needs to read a 25mm token at about 100 mm away from the reader’s antenna plane. Can anyone opine whether the electronics in the RDM630 are up to that?