Another directional loop antenna for RFI location (2019), https://www.arrl.org/files/file/Antenna%20Book%20Supplemental%20Files/24th%20Edition/Handheld%20DF%20A

Another directional loop antenna for RFI location (2019), https://www.arrl.org/files/file/Antenna%20Book%20Supplemental%20Files/24th%20Edition/Handheld%20DF%20Antenna%20-%20NA6O.pdf https://www.arrl.org/files/file/Antenna%20Book%20Supplementa... Here is a simple antenna design that is effective from 3 to 22 MHz. Based on a resonant magnetic loop, it has high transducer gain (high sensitivity), and also very good directionality. You can build it cheaply from junk box parts.