Re: LF: Original 73kHz first.

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

As a rule of thumb, the near / far field transition is taken to be lambda/ 2.pi   Where the reactive fields are down to below the level of the radiation .

So for 137kHz that lies at 350m     and for  475kHz at 100m

For accurate measurements in the R field, you therefore need to be 2 - 4 times further away than those values give you.

AFAIR, the magnetic field falls of faster than the Efield, but both faster than the radiation .

'jnt

On 21 February 2016 at 10:22, M0FMT <m0fmt@yahoo.co.uk> wrote:

Hi all

Where does the distance for capaciive and or magnetic coupling end and the main mode of electromagnetic radiation coupling begin? Is it defined?

73 es GL Pete M0FMT GQRP#15097.in IO91UX


Sent via my own personal Too-Way (two way) Earth Station to and from the Eutelsat Ka-band satellite  http://www.tooway.co.uk/  at approximately 172 degrees Azimuth in the Clarke belt owing to BTs 19th century cable technology inability to provide a good enough 21st century broadband service. I agree for this message to be passed on to BT Plc at 81 Newgate Street, London EC1A 7AJ  via the snoops at GCHQ Cheltenham, thanks for your cooperation it is appreciated.

--------------------------------------------
On Sat, 20/2/16, F6CNI - Andy - JN19QB <f6cni@orange.fr> wrote:

 Subject: Re: LF: Original 73kHz first.
 To: rsgb_lf_group@blacksheep.org
 Date: Saturday, 20 February, 2016, 7:54




 Hello Andy.
  
 Not about the first claimed 73kHz QSO, but just for
 info
 :
  
 the first time I heard Peter G3LDO on 73.4 kHz normal
 CW (
 338 km ) was around november / december 1996. Later, I had
 my first xband QSO
 73.3 / 3.570 kHz with him 28 march 1998. I received his nice
 QSL for this event.
 It was, I think, the only all time QSO normal CW xband from
 UK to outside UK.
 But Peter and probably others UK stations had also some
 “DX” QRSS QSO xband 73 /
 137 : one day ( I do not remember the date ) I see Peter in
 QSO QRSS3 with
 HB9ASB...
  
 73 de Andy F6CNI.

  
 From:
 Andy
 Talbot

 Sent: Friday,
 February 19, 2016 11:40 PM
 To:
 rsgb_lf_group@blacksheep.org
 ; rsgb_lf_group@yahoogroups.co.uk


 Subject: LF: Original
 73kHz first.
  

 Can anyone remember what the first claimed
 73kHz QSO  was
 .  I seem to remember it was a few tens of metres across a
 car park,
 probably in 1996

 (Strictly, that was a capacitor not radiation,
 but...)
  
 I'm giving a talk on LF/MF in a couple of weeks,
 and want to get the
 timeline right.
  
 Andy 
 G4JNT