Sunday, 28 January 2018

Short 40m Vertical - WSPR tests.

Last summer, I wrote about an experimental, centre-loaded vertical for 40m that, surprise, surprise, worked rather well.

The only problem then was that my QTH is rather full of antennas, and I wanted to set up the short vert in a clear site, where it could all be carefully tweaked for peak performance.

With a new marsh site to play in, I now had the chance to do exactly this!

Here are the afternoon-evening WSPR results of the short vertical compared to a half-sloper, which is cut for 40m, hung and fed against my lattice tower:

Comparison of S/N, all distances.
The advantage over all distances is significantly in favour of the short vertical, at 2dB better than the half sloper.

This was the range outcome:

MW1CFN (blue) = short vertical; MW6PYS (red) = half sloper.

Overall, a slight advantage in range terms to the half sloper.  Here's the map of spots, showing DP0GVN hearing both stations (this is only one set of spots of many):

Next, a quick look at how the S/N compares out beyond 2400km, which I choose as the boundary between DX and non-DX:

A slight advantage of 0.75dB to the short vertical.

Comparison with G0ORD at long-haul DX, running what I think is an inverted-L at much higher output  (5W), looks like this:

Looking carefully at all other stations in the UK, the WSPR database shows that only G0MRV approaches the effectiveness of this antenna, although on sheer DX reach, he does not overtake the short vert.  The vertical performs at the same or slightly better level as a half sloper hung off a metal tower in a similar environment.  So, just like last summer, the objective, human-free WSPR tests confirm the short vertical is in no way a compromise antenna, and is indeed a very effective one, doing very well against full wire antennas running higher output.

The real advantage for the short vertical is that it fits easily on a cheap 7m-tall fishing pole, resists very strong winds (tested to 50mph so far), and is generally much easier to accommodate than a half sloper (needing a fixed metal pole of significant height) or dipole (needing two or three such supports).  It's also very portable, and very easily deployed wherever the fancy takes you!

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