At VHF the small loop can be a full wave loop. A loop of 1m diameter would be 3.14 m in circumference so would resonate around 95 MHz for FM broadcast listening.
A 800 mm diameter loop would resonate around 120 MHz for airband listening.
A 650 mm diameter loop would resonate around the 2m amateur band.
Regarding the bias-tee or base unit options, the bias-tee is best if you want the best dynamic range with a good receiver.
The base unit has an extra amplifier which helps poor low sensitivity receivers but may overload good receivers.