[Lowfer] Frequency usage question

[Warren K2ORS]

On the subject of multiple loops, I recall that at one time Bill Ashlock 
had two lopps, a N-S and an E-W. He would transmit a "W" on one loop and 
an "M" on the other.

Loop directivity is not a deal killer though, my Part 5 137kHz signal 
has been copied in South America even though the loop is oriented to 
have its maximum in the E-W plane.

Warren



On 11/12/2014 9:02 AM, JD wrote:
>>>> And for Part 15, the vertical is more defensible for regulatory
>>>> purposes than a 50x50 foot loop.
>
> Not a trivial concern, IMHO.  Equating a 200 foot run of radiating
> conductor to the total length of 15m specified in the Rules is quite a
> mental challenge.  (Conversely, for Part 5 Experimental Service
> licensees or hams in countries with LF allocations, it's no issue at
> all.  Licensed operation might be a better alternative than Part 15 for
> anyone stuck needing to use a loop because of local arboreal
> circumstances, anyway.)
>
> Along with that concern, plus the lower radiated field strength for a
> given physical size as John A mentioned, the third disadvantage of a
> transmit loop is that it is directional.  The very property that
> generally gives loops a big advantage for receiving can be a detriment
> when transmitting.  Prime example:  On 2200m, I can generally see MP day
> and night because my QTH lies roughly in the same alignment as Mitch's
> loop; whereas MP is a nighttime-only catch for other folks who are at
> comparable distances or even nearer, but who are located off to the
> sides of the main lobes.
>
> There are ways to fill the nulls of a loop, of course, but either at the
> cost of efficiency (ie, intentional or accidental coupling to other
> conductors--or even semiconductive natural objects--in the vicinity) or
> else by implementing a second entire loop and feeding it in
> phase-quadrature, which is even less realistic for Part 15.
>
> John D


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