Two presentations, one by John DeMajo, K5HTZ, and a second by Ken Zutavern, K4ZUT, at the 10 January 2020 RARC club meeting are outlined here.
John DeMajo Mag Loop presentation
John‘s presentation is available by clicking this link: loop-antenna-project
John’s spreadsheet calculator is at mag_loop_calculator.
Ken showed another design that used a hand-wound toroid transformer instead of a small loop to feed the large loop.
K4ZUT toroid transformer and motor-driven capacitor tuning
Ken’s loop also used a motor to turn the tuning capacitor. This allows him to locate the loop away from his operating position.