My RX LOOP is VERTICAL with a perimeter
length of 850 feet total. I have not noticed any static built up or
flashing regardless of wx. The height is 100 feet, however the TX 1/4 wave
inv L up at 100 feet with 2 elevated radials about 7 feet above ground does
flash across the coax plug when disconnected from the TX. under
certain atmospheric condx. This loop works well on both LF and MF and is
parallel tuned for resonance on the appropriate band.
A so called horizontal loop is probably not
desireable on LF/MF its is just a large capacitor gathering static.