Is this a common-mode interference? Seek for a solution ..
i spent a little while trying to resolve the interference patterns shown in the picture (in the interval of 1.7~5.0 Mhz)
Currently, a Galvanic isolator has been implemented and works well for LW band noise.
A low-pass filter (DC-30Mhz) installed, and it has been proven nothing to do with this interference patterns.
No balun nor a so-called common-mode choke installed yet in my antenna.
Could a common-mode choke be useful for my problem ?? or such device would be of no use ??
just a amateur noob, not so familiar with antenna theory ....
Need your kind opinion for this very much.