Re: LF: Re: Loop TX antennas at VLF?

[Markus Vester <markusvester@aol.com>]

Mal,

 

in our context, magnetic stimulation should not be a real problem. Around 9 kHz, ICNIRP guidelines (which do include a large safety margin) allow 24.4 A/m for occupational exposure and 5 A/m for the general public. A loop wire carrying 100 amps generates a very moderate 8 A/m at 1 m radial distance. On the other hand, 0.35 amps into my loading coil generates about 4 A/m at 1 m from the axis. 

 

Actual stimulation thresholds are typically two to three orders of magnitude higher. Using ear plugs, I inserted my head into the opening at the cold (!) end of the coil for a few seconds. The magnetic field (approximately 1000 A/m) produced no perceivable effect.

Best regards,

Markus (DF6NM)

-----Ursprüngliche Mitteilung-----
Von: mal hamilton <g3kevmal@talktalk.net>
An: rsgb_lf_group@blacksheep.org
Verschickt: Mo., 21. Mrz. 2011, 19:54
Thema: Re: LF: Re: Loop TX antennas at VLF?

Markus

On health grounds I will leave loops alone. Your closing paragraph refers

de mal/g3kev

 

----- Original Message -----

From: Markus Vester

To: rsgb_lf_group@blacksheep.org

Sent: Monday, March 21, 2011 6:42 PM

Subject: Re: LF: Re: Loop TX antennas at VLF?

...

As the antenna is likely to be built in an inhabited area, you may also want to consider that magnetic fields are not shielded very well by most housing construction materials. They will also penetrate our bodies, with an (at least theoretical) possibility of nerve stimulation in the immediate vicinity of very large AC currents.

...