[UK-CONTEST] Antenna for SSB field day

[Andy Summers]

  Hi Rob,

It sounds like the precedent has already been set to allow a fan dipole, 
or whatever you want to call multiple elements on a single feedline. So 
I'd go ahead with that unless you're specifically told not to by the 
contest committee.

I'm all for trying not to be too descriptive with the rules, but what I 
do object to is successive committees giving inconsistent replies to 
questions about the rules.

Presumably, the idea of the restricted section is to allow entrants to 
be competitive with a minimum of hardware (and money). So I would 
imagine the phrase 'single element' is used in the parasitic or driven 
array sense. Would you say that your fan dipole is a 4-element array? 
No, you wouldn't!

Chris asked why you would want to use a fan dipole. I can't imagine a 
cheaper, simpler antenna. No ATU required! It also allows instant QSY.

You can get gain of course from a single element, as others have 
mentioned, but you can only optimise this for one band, and the 
feedpoint impedance is now nowhere near 50R. If you try to common lots 
of these higher gain doublets (or loops) it doesn't work, because the 
method relies on power matching to select the appropriate element.

The 'one antenna only' rule must be trying to stop you from having 
separate optimised antennas for each band. Personally, I don't see this 
as a big problem anyway because of the single element and only two 
supports restrictions. But does this rule have to be adhered to over the 
entire contest? If so, then adding wire on in the evening to improve LF 
performance is against the rules.

What about adopting the 21/28MHz antenna rules...

"Restricted - a maximum of 100 watts output and only one antenna per 
band, which must be a single element with a maximum height of 15m"

But maintain the two supports rule?

I think this would make it easier to get a simple station on, and at the 
same time possibly result in better signals and more Q's (especially 
10/15m).

73,
Andy, G4KNO.



On 13/08/10 01:37, Rob Hall M0RBY wrote:
> There are only so many variations on a theme! If a fan or common feedpoint
> dipole is classed as a single element or just a simple doublet of a length
> left up to the station concerned and any non-amplifying AMU introduced then
> I might understand the "rules" but they are a tad ambiguous and I have had a
> few differences of opinion!
>
> Again, I will use the proviso that this is my first ever contest and I
> really, really don't know.
>
> 73, Rob
>