[UK-CONTEST] Antenna for SSB field day

[Chris G3SJJ]

  Rob, welcome to contesting!

I suggest you look at the last few years results and reports to get a feel for your strategy - bands and times etc.

As far as I am aware paralleled dipoles are classed multi element. Why not try the following which Dave G3ZQH and myself will be using.

Two 50ft masts with an 84ft doublet strung between the two. Orientate the masts in a line approx 20/200 deg. This is an Extended Double Zepp for 20m, 
giving broadside lobes  for Eu and US with gain plus some useful high angle on that band. On 40m you also get good broadside lobes. The RF sprays 
around a bit on 10m and 15m!

When 20m dies out and you want to go to 80m, quickly drop the antenna, connect a 44ft extension to each end and haul the antenna back, then stretch 
the extensions out by adding some rope to each end to get them as least sloping as possible. As soon as dawn arrives and 80m propagation closes, take 
the ends off and just use the EDZ for the rest of the time.

A sophisticated variant would be to add a vacuum relay at of the two joints and bring a switching cable back to the shack. If you have a band decoder 
eg Topten or Elecraft KRC2 you can make it auto switch when you change bands.

I have modelled this on EZNEC and the feedpoint impedance looks fairly low on all bands so it should be feasible to run it through a 4:1 balun and 
just use the internal in the radio.

Dave and I have some further checks to do on this, but we have a selection of atus available if it doesn't work!

I have a Word doc with the EZNEC plots if anyone wants it.

Chris G3SJJ




On 09/08/2010 23:35, Rob Hall M0RBY wrote:
> Hi,
>
> Hello all, I am new to the list and, potentially a convert to contesting. A
> question that I have is regarding the antenna; this is my first contest ever
> and I have been charged with sorting the antenna out. We will be operating
> in the restricted section and the rules state that we can have one antenna
> which must be a single element.
>
> My question is, does a fan dipole count here as a single element given that
> only one element is resonant per band? We have had a few lively
> conversations about this at our club with some claiming that the cobwebb is
> "single element" for similar reasons! If not, then I am happy to shove up a
> doublet and pop an ATU in there. We are keen to enter the contest in fair
> spirit so I'd like to get it right before embarking on the work.
>
> 73, Rob M0RBY