[AMRadio] New VLF bands


Kim Elmore cw_de_n5op at sbcglobal.net
Wed Apr 29 22:29:34 EDT 2015


Well, yes... But the FCC limited us based on effective isotropic 
radiated power (EIRP). No antenna we can build is very efficient at LF, 
and the FAA doesn't go the great lengths in this regard, either, so I 
doubt that the NDBs you mention have a very high EIRP.  Someone 
mentioned that, depending on antenna efficiency, it might take nearly a 
KW to get 5 W EIRP.  Antenna limitations will also limit bandwidth at 
LF; the signal rate will have to be very low. At MF, the antenna still 
limits bandwidth to some extent, but the limits aren't as severe. Thus 
we hear both AM CW and speech on the NDBs.

While this will be interesting, it will also be a very specialized 
segment that do anything at LF. The new MF allocation will be closer to 
what we're used to and will likely get more use.

On 4/29/2015 8:49 AM, CL in NC via AMRadio wrote:
> Not sure what can be done with 2KC of band, but as a person who occasionally listens down there in the winter, I wouldn't mind having access without having to jump through the ARRL's hoops.  I find it ironic that the FCC considers the first users of this spectrum 100 years ago with spark and arc TX's as a threat today with modern components and designs. The biggest screw over the FCC hits us with is the power limit.  Aviation aids, NDB's and LOM's operate from 25 watts, to 1KW with no issues, usually feeding top loaded towers or center fed 'T' antennas with the power line going right to the TX shack overhead and near the antenna.  I brought this issue up on an FCC  comment years ago but who knows if they even read comments from the peanut gallery.
>
> Charlie, W4MEC in NC
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-- 

Kim Elmore, Ph.D. (Adj. Assoc. Prof., OU School of Meteorology, CCM, PP 
SEL/MEL/Glider, N5OP, 2nd Class Radiotelegraph, GROL)

/"In theory there is no difference between theory and practice. But, in 
practice, there is." //– Attributed to many people; it’s so true that it 
doesn’t matter who said it./



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