[Fwd: Re: [Lf] [Fwd: LF: No US Ham Band]]

[Andre Kesteloot]

  Gary,
I am forwarding your reply to the AMRAD LF reflector
73
André

-------- Original Message --------
Subject: Re: [Lf] [Fwd: LF: No US Ham Band]
Date: Sat, 17 May 2003 18:54:46 -0600
From: "Gary Peterson" <glpeterson at tfcbooks.com>
To: <andre.kesteloot at ieee.org>
References: 
<3EC304BF.1000903 at verizon.net><050201c31c90$87a1c4a0$040ac1d8 at hppav> 
<3EC6979E.1030508 at verizon.net>



Hi André,
 
You wrote:

    The problems of  radiating any kind of power at all at 73 kHz are a
    good deal worse than at 136 kHz, and I would not see any advantage
    to that band.

I wish to study the characteristics of a poorly described LF 
surface-wave and the apparatus for its production.  The launching 
structure, which has been called a grounded antenna, consists of a very 
well grounded, high aspect ratio helical resonator connected with 
a short vertical conductor to an elevated armature of large surface area 
and radius of curvature.  Antenna excitation is by means of a few 
primary windings in more or less close proximity to the lower part of 
the resonator.  I've read the propagation efficiency of this surface 
wave improves with a lowering of frequency, making the 73 kHz band 
preferable to me.  I've also read this wave is not a major contributor 
to the field produced by base-loaded monopole LF antennas, another 
potential area of inquiry.
 
The receiving apparatus for this purported surface wave includes a 
matched helical resonator grounded at the lower terminal and the 
upper terminal connected to an elevated armature.  See 
http://www.tfcbooks.com/special/images/system.gif for an old sketch of 
the entire system.
 
73
Gary KB0DEB

    ----- Original Message -----
    From: Andre Kesteloot <mailto:andre.kesteloot at verizon.net>
    To: Gary Peterson <mailto:glpeterson at tfcbooks.com>
    Cc: AMRAD Tacos <mailto:tacos at amrad.org> ; lf-amrad
    <mailto:lf at amrad.org>
    Sent: Saturday, May 17, 2003 2:12 PM
    Subject: Re: [Lf] [Fwd: LF: No US Ham Band]



    ------------------------------------------------------------------------

    Gary Peterson wrote:

>     I understand that at one point a 73 kHz shared allocation was
>     being talked about and that UK hams were authorized to use that
>     band for a while, back in 1996.  Do you think the ARRL would
>     consider petitioning the FCC for ham privileges between 71.6-74.4 kHz?
>      
>     I know some fixed European stations have frequency allocations in
>     that area.  Are there PLC concerns associated with that portion of
>     the spectrum as well?  
>      

    Hello Gary,
    Yes the 73 kHz band is still in use in the UK but, as I understand
    it, is due to be phased out in the near future. As far as I know, no
    new user may be authorized to use that band in the UK.
    One of the early advantages of 73 kHz was that one could use regular
    high power Hi-Fi audio amplifiers whose bandwidth would easily
    extend that high.  
    Now that we better control the problem of building transmitters with
    cheap Power MosFETs, that advantage has really disappeared.
    The problems of  radiating any kind of power at all at 73 kHz are a
    good deal worse than at 136 kHz, and I would not see any advantage
    to that band. One of the challenges that motivated us was the idea
    of trans-atlantic QSOs on 136 kHz. That has now been effectively
    killed by our dear FCC wizards.
    As far as the PLCs are concerned, you understand, I am sure, that
    they do not have any privilege on 136 either. They are secondary
    users.  I have no idea whether they have equipment on 73, as they
    would not even tell us the frequencies they use on the LF band
    73
    André  N4ICK

    ------------------------------------------------------------------------

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