Your antenna's Z in the 40M band is astronomical:
Impedance = 12740 + J 8376 ohms
in the 80M band
Impedance = 98.29 + J 1069 ohms

Skip the lore about baluns (which you couldn't possibly hope to
find/build/buy), what you need is a tuner and second smaller loop
(think half the size) in parallel with the big one (to pull down that
astronomical mismatch).

73's
Richard Clark, KB7QHC

With such a high VSWR the loss on 100 ft of 450 ohm ladder
line is only about 1.1 dB on 7 MHz. Typical tuner loss about
0.5 dB.

Frank