There is a good reason for this. I've worked RFI/EMC for some 35 years.
FCC, the EU, and most other agencies require the following:
Radiated Emissions: Lower Limit is 30 MHz Upper
limit (FCC): Highest frequency generated or used, and if you generate it
you use it. Or 40 GHz.
Conducted Emissions: Lower Limit is 150 kHz Upper
limit is 30 MHz
Look at an average house. There are many conductor runs that might
resonate as high as 30 MHz, but not much above. My favorite is 40-meters
where there are multiple conductor runs, both power and heating, that are
between 60 and 30 feet. If energy is coupled onto these conductors, they
will radiate just like an antenna fed with energy. What's more, most
products have sizes that might resonate/radiate above 30 MHz, so they are
potentially good antennas/radiators. The conducted energy by itself needs
an antenna to radiate - longer wavelengths. So the regulatory agencies
looked at this and put limits on radiated emissions directly from the EUT
with its smaller dimensions and conducted emissions which rely on larger
antennas that the EUT does not provide but house wiring and duct work do.
Dave - WØLEV
On Wed, Sep 22, 2021 at 5:05 PM Bill Mader <billamader@gmail.com> wrote:
> The link below comes from a microwave journal but contains an EMI allowable
> levels chart that goes down to 30 MHz, down to is the point. We all know
> RFI/EMI is increasing, but especially in the HF spectrum. I hope W1RFI's,
> and others', involvement with the IEEE on RFI/EMI will help add focus to
> the mess on HF!
>
>
> https://www.microwavejournal.com/articles/36728-addressing-emc-challenges-in-electric-vehicle-supply-equipment?utm_source=MV_Microwave+Journal+Flash&utm_medium=email&utm_content=HTMLLinkID%3a+18&utm_campaign=Weekly+News+Update%3a+OneWeb+Successfully+Launches+34+Satellites%3b+GF+%26+Qualcomm+Sign+Agreement+for+5G+RF+Front%e2%80%90Ends
>
> I worry that this aspect of "clean" energy will increase what we experience
> on HF by orders of magnitude!
>
> 73, Bill Mader, K8TE
> New Mexico QSO Party 9 Apr 2022
> ARRL New Mexico Section Manager
> *ARRL - The national association for Amateur Radio**™*
> Duke City Hamfest Chairman www.dukecityhamfest.org 16-18 Sep 2022
> Secretary/Treasurer and Past President, Albuquerque DX Association
> W6H NM Coordinator, Route 66 On-the-Air 10-18 Sep 2022
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>
--
*Dave - WØLEV*
*Just Let Darwin Work*
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