[UK-CONTEST] Vertical Dipole

[mm0bqi]

Thanks for all the comments and advice on/off the reflector.
I will go with the vertical dipoles.  Set them up in the garden yesterday
and they are very touchy regarding the angle at which the coax leaves the
feed point.  Changes the resonant frequency and SWR.  However six feet along
a cane then a gentle slope seems to be a happy compromise.
There seems to be no advantage and some significant disadvantages if I raise
the bottom of the dipole too high.  The following is what I will go with.
20m bottom of dipole leg at 2m AGL and feed point 7m AGL
15m bottom of dipole at 1.5 m feed point at 5.25m
10m bottom of dipole at 1m and feed point 2.5m
The sea will be in direction of EU/AS/OC but that leaves lots of peat and a
very large hill to the west of me.  I just wanted to confirm that I will not
be 'losing' too much signal in these directions just because the antennas
are close to the ground?  (Need to get out of the higher/bigger is always
better mindset!)
73
Jim


On 25 July 2011 18:26, Clive GM3POI <gm3poi2 at btinternet.com> wrote:

> Jim,
> I should have added keep the antenna within 0.1 wavelength of the High
> water mark, and don't choose a site with a large low/high sea, distance
> change. 73 Clive GM3POI
>
> On 25/07/2011 13:49, mm0bqi wrote:
>  > Following some very helpful and interesting comments last year about my
> IOTA
> > contest ground plane antennas I have gone for a change this year.
> During
> > our recent EU108 expedition we tried vertical dipoles beside the sea and
> > they seemed to work.  However I am not fully convinced but feel it is
> worth
> > having a go!  I have two questions.
> > 1.  Will there be any great performance difference between the two types
> of
> > antenna?  My main target area is EU and I have a clear sea path to VK/JA
> > should the bands open....
> > 2.  The antennas will be on 12m fishing poles, does the height of the
> feed
> > point matter or should I just make it as high as possible?
> > Each antenna 10/15/20m will be taped to a separate 12m fishing pole and
> > they will be within 5m of the sea.  The coax will come away at right
> angles
> > along a cane for about six feet then slope to the ground at about 45
> > degrees.
> > Thanks
> > Jim,  MM0BQI
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