Saturday 18 September 2021

Thoughts turn to summer.

One band I haven't tried from the beach is 6m.  But with such great success on other bands, I think that come next summer, I should have a go.

One nice thing that's possible on 6m, where it isn't really on other, upper HF bands, is using a Yagi in a vertical configuration.  This should provide really quite spectacular outcomes for DX paths from the coast, such as that to Japan.  Due to convention and the lack of suitably-located operators, such vertical beams seem to be extremely rare.  

I'm going to try some 6m Far East DX next summer...
 

Let's see how this works out at 10m, which is a stock, 6-ele model provided in MMANA-GAL, simply for convenience; the general outcome will be much the same at 6m.  First, the horizontal pattern, using an 8m mounting height, which is about the maximum we might reasonably achieve on a portable outing.  Ground type is 'perfect', which is not too far from what we get with seawater:

    

And now, turning the beam on its side so that it's vertically polarised:



The difference between them is enormous at very low angles; we get 17dBi right down to the horizon, whereas the horizontal beam has a big gap starting below 15 degrees, falling away to very poor radiation at much lower angles. 

To put this into context, a 5W input would come out as 250W.  10W as 500W, and so on.

Colleagues such as PE4BAS have a good track record of making JA QSOs with horizontal beams each summer.  I never really put in enough effort, nor had a particularly good aspect towards JA from my last QTH.  I hope to change that now.

Hopefully, I'll have a drive-on plate and modest mast and side arm to mount a vertical 6m Yagi done-up over the coming winter.  Or maybe I'll try a rear-mount quad array, as supplied by Innovantennas?  We'll see...




2 comments:

PE4BAS, Bas said...

Just to be clear that, waht you show, is near water and at low (8m) height. Just like DXpedition use a VDA close to the water with excellent results. I think you have a point and hope to read some very interesting results next year. One big tip is to listen/view west at the greyline in the evening. It gave me some incredible contacts on 6m. 73, Bas

Photon said...

Hi Bas. Yes, by maybe even 8m is a bit ambitious for a portable set-up with a 6m Yagi. Maybe not so much for a quad. When I ran the model again with a minimum height of ~4m (boom at ~5m or so), the gain was still the same. When I dropped it to a lowest point of just 1.5m, it was still only down by 1dB or so. Good news, because height is always more difficult to achieve than we think when portable!