Hello I want to build an untuned (broadband) magnetic loop for LF to HF (100KHz-30MHz) reception.
The loop must have the next characteristics:
Frequency of coverage: 100KHz-30MHz
Design:
https://i.stack.imgur.com/LgKnc.png
A preamplifier with about 20db of gain will be used to make it an active loop
https://www.g8jnj.net/activeantennas.htm
To be "magnetic" at HF and below, the loop should not be big. But how small can I make the loop, so as not to lose the directivity (nulling) feature at these frequencies and at the same time provide reasonable reception sensitivity (based on my 20db preamplifier)?