Re: LF: VLF Earth Mode does NOT need an NoV - official at last

[Andy Talbot <andy.g4jnt@gmail.com>]

Which raises the issue of the antennas for ULF Submarine comms.   Could it be said that feeders of hundreds of km length terminated to ground at the far end are used solely to get a wide spacing in the ground with the feed itself not contributing to the radiation.    In which case the resulting ground mode comms must pass right though the earth - including its iron core.  No, perhaps not.

 

But it makes you think - when does earth mode - non-licensable -  become radiative from the loop of feeder and ground return path?

 

Andy

www.g4jnt.com

 

 

On 18 January 2011 15:44, Chris Trayner <C.Trayner@leeds.ac.uk> wrote:

Hi Roger,

On 2011 Jan 18, at 15:11, Roger Lapthorn wrote:

> Today I received this letter from OFCOM, which clarifies the legality of operating so called "earth mode" (conduction/induction via the ground) experiments at frequencies below 9kHz in the UK. Note the sentence in Paul's letter saying, "We would not normally issue NoVs for communications using non-wireless telegraphy apparatus/stations i.e.  where you rely only on conducted emissions and where there are no intentional radiated emissions.".

Maybe.

Saying that they don't normally issue NoVs could mean that NoVs aren't needed, or that they are needed but that OFCOM would rarely grant one.

I suspect that their intended interpretation is what you say, and that they simply haven't written it unambiguously. I'm willing to say this in your defence in court ;-)

73,
Chris G4OKW

-----------------------
Dr Chris Trayner
School of Electronic & Electrical Engineering,
The University of Leeds,
Leeds LS2 9JT, United Kingdom
Tel: +44 113 34 32053
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