[Fwd: LF: Loop vs Marconi]

[Andre Kesteloot]

Intersting stuff about loops.
André N4ICK
*******************************
Mike Dennison wrote:

> G4JNT wrote:
>
> I still maintain that if antenna size is restricted by a small house
> / garden and massive high masts are not possible, wire antennas have
> the edge over loops.  There must be a break even point somewhere and
> my gut feeling is that this is somewhere in the region of a garden 30
> - 40m long and a maximum height of 10 - 15m.
> ---------------------------------------------------------------------
>
> I think I am the only one to have run a medium sized loop and a
> Marconi, and compared them.
>
> My loop was rectangular and about 8m vertical by about 10m
> horizontal, and around 1m above ground. It was shunt fed and tuned
> with a parallel capacitor, resulting in several amps in the vertical
> section. Loop resistance was 2 ohms. This performed quite well with a
> range of about 30km with 30 watts.
>
> I replaced it with a Marconi with similar dimensions (9m high by
> three wires 20m long) and this increased the range by some 50%
> immediately. It was also noticeable that the signal dropped off less
> quickly with distance.
>
> The loop appeared to suffer from directivity and, if you have
> limited options as to direction, you may miss the stations who are
> active.
>
> So, with a garden smaller than that specified by Andy, the Marconi
> wins. However, the loop is very easy to set up, requires no loading
> coil and no earth. It would therefore be suitable for portable use
> (I have always wanted to experiment with a triangular sloping loop
> with a single tree support) or as a first LF antenna. It also works
> well on receive.
>
> 73 de Mike, G3XDV
>
> Mike