Other Reference Material:

Everett Sharp N4CY has permitted me to post his experimental results using an full-wave horizontal loop for HF:

80 Meter Horizontal Loop Antenna, Everett Sharp N8CNP

Experimenting with different Baluns on a 275′ Horizontal Multi-Band Loop Antenna 80/40/30/20/17/15/12/10/6m Everett Sharp N8CNP