[UK-CONTEST] Vertical Dipole

[Clive GM3POI]

Jim, If you feed the dipole  via a good quality choke and bring the coax 
down a guy line at an angle of 45 degrees or flatter all should be ok. 
73 Clive GM3POI


On 26/07/2011 13:45, mm0bqi wrote:
> 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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