First step, improve the loop; either use some copper pipe or alumium strip to make a wider and BIGGER loop (easy)
Second step; match the impedance, the preamp has an impedance ranging from 1.5K down to 450Ohm, now ler's find a balance, break the loop at top and use a 975Ohm resistor to connect the two halves
Third step: the preamp to bias tee coax sucks badly, add a BNC connector to the preamp box and use a run of decent coax (RG6 will do) to feed the loop
Fourth step: the BIAS Tee unit was designed by a drunk folk, replace it asap
