Inverted V vers Vertical on 10m

The 10m band session is open and many of the activators are only calling on 28.xxxMHz. (tnx Armin for qsy).

This makes me ask myself again whether my beloved 20m long efhw can do that as an inverted vee. That’s why I made the comparison again with a vertical 4.8m long efhw.

Here is the first result, more on that later.

73 Chris

13 Likes

Your video proves what I thought but have never had time to try. Thanks. I would love to see what the difference is when you transmit using the antennas. That would take a bit of organising though.

I did think about cutting a 5m long EFHW and using it on 10m as a vertical. However I have come to the conclusion that my 10m operating falls into two caregories.

  1. A specific 10m session on an accessible hill in good weather. I’ll carry my fibreglass 7m pole and ¼ vertical with sloping radials.

  2. A multiband activation on a longer hike, in less good weather or limited operating time. I’ll use a single antenna in my carbon 6 mast, either a 41’ random or 20m long EFHW.

2 Likes

It’s seemed to be a significant difference on the vertical. I had same TEST DE DL1CR/P on the vertical and DL1CR on inv vee. The results on Reverse Beacon Network below.

It was a very short test, today i will repeat it.

73 Chris

2 Likes

Exactly my thoughts, Fraser
The vertical does better for DX, and can get better low-angle radiation on the right hill, but needs the 7M fibreglass pole. The Carbon pole is too short and also detunes the antenna.

But the endfed works pretty well too !

Rick

2 Likes

I think that the important factor is the azimuth radiation pattern. The 20m long antenna is two wavelengths long on ten, this means that its azimuth pattern has four lobes with some gain, and four deep nulls. This means that you will have four directions where it performs really well, and four directions where it performs very poorly. On the other hand it also produces four lobes in the vertical plane, two at a low angle suitable for DX, and two at a much higher angle that would be usefull during the sporadic E season when the skip is short. The two lobes are separated by a null at about 30deg which could be a disadvantage for some distances. A quarter wave vertical has no nulls so you can receive signals equally well from all directions, but it has less gain than the efhw. However it has just two broad lobes lobes in the vertical plane extending to a somewhat lower angle that would be a little better for long haul DX and with no null in the lobe so it would be better for sporadic E at intermediate distances.

My conclusion would be that if you are only operating on ten then the vertical is more convenient and has no directional disadvantages. The 20m inverted V has some disadvantages for ten but is conveniently multiband. The ideal is to have both!

In my case, at present I am chasing with a 40m long doublet. This has eight lobes in the horizontal plane, four of them with significant gain, but also has eight nulls with significant loss. It also is less useful for the higher angle sporadic E signals, so despite its gain in four directions it is not a satisfactory antenna for ten and when the weather inproves I shall erect a dedicated antenna for ten.

My information on the radiation patterns were taken from L.B.Cebik, W4RNL (SK).

7 Likes

A few days ago I did a similar test on DM/BW-018.

I set up 2 10m telescopic masts from DX-Wire at a distance of 10m.

A J-pole antenna made of RG-174 built for 10m was pushed up on one of them… and on the other my end feed for 40/20/15/10m was pushed up as inv. V

In European QSOs the J-Pole was up to 2 S levels worse… in the DX QSOs with USA it was almost as good - but never better than the endfed.

73 Armin

3 Likes

How can you tell? It’s only three stations that reported on both antennas and they’re from Europe.

today i will repeat it.

Yes, unbedingt! :slight_smile:

Ahoi
Pom

In addition, results of antenna comparison tests with a time interval of 1 hour, in general and on the 10 m band at this time of day in particular, should be viewed with particular caution.

6 Likes

Yes, that’s what I was alluding to. You would need a dx (eg USA) friendly chaser who could give reports on A versus B. A digital mode such as FT8 could also be used to get reports.

Well, yes … and no. Now, understand I’m not speaking here as an expert, but the little I do know has been gleaned from online sources, such as those from L. Cebik whom you quote. A NEC-based program would show how a 20m long EFHW would perform in various configurations - I’ve used one of these to model such an antenna in two different configurations: as a flat-top, and as an inverted-vee similar to that used by Christoph DL1CR, and the results are presented here (the antenna is oriented 0°-180°, or E-W):

Both configurations - idealized of course - include a short (2m) horizontal counterpoise, and the antennas are 9 meters high at their highest point. As can be seen from the diagrams, the flat-top does indeed show the deep nulls in the propagation patterns you mention, with a low vertical first lobe, as would be expected from a dipole of this length operating on 10 meters. The inverted-vee (with legs at 40° from vertical), however, shows much different patterns, and indeed has just one vertical lobe at about 40° above the horizontal - not great for DX. These are, of course, results from just one (online) NEC-based tool - other such tools are available.

1 Like

Hi Chris ! Thanks for the experiment. And I agree my “just using it” experience is that i get much better DX with 1/4 vertical, than an end fed in L / inverted V. But my end feds have been somewhat dubious :slight_smile:

I can not tell the difference between 1/4 Vert with one radial or 3 radial. One radial works well for me, (no quantitive tests, just me gut feeling) and is super lightweight (78g) and super fast to put up. In these conditions i always carry it now.

and i wonder why no-one is using a 1/2w, other than size and convenience.

Thanks Tim

1 Like

It goes back to the argument of do you just want contacts, or do you want dx? As I said in my recent report, a 49:1, some RG-174 and an inverted V 40,20,15 & 10m EFHW will work, even with QRP. A dedicated antenna will work better.

However, when 10m is really open I don’t think you’d much difference. You could work dx with a telescopic whip.

A half-wave for 10m (without an auto-transformer) would need a decent radial field as well.

1 Like

I’m using a flowerpot style vertical which is 1/2 wave, but bottom fed to make it easy to feed and no radials required

Rick

3 Likes

Yes, fair point. And the decision to be quick with no faffing on a summit goes a long way too…

3 Likes

Just my take on this matter, I just made quick comparison between

Vertical - Xformer 3mtr agl EFHW10 wire tuned for 10m band
inv-V - Both ends at 2mtr agl apex at 10mtr EFHW4010 20.5mtr wire, end of antenna pointing North
inv-L - Xformer at 2.5mtr agl, apex at 10mtr EFHW4010 20.5 mtr wire, end of antenna pointing North

First IMO we should to consider propagation conditions on 10m band and most likely source of QSO

Afterwards we could select based on radiation patterns and antenna gain at 10deg take-off angle to match conditions

Ignore SWR as it was quick run just to demonstrate different options.

Considering most likely source of DX QSO we can adjust out antenna setup accordingly

73 Marek

5 Likes

Thanks Marek for the clue to look up the DR2W DX-Propagation tool - I did not know about this!

Cheers, Rob

1 Like

Not great for DX, as you say, but acceptable for Es. I remember about twenty years ago conducting tests during an Es opening on 6m with an Italian station who could tilt his beam at various angles above the horizontal. His signal showed a definate peak at about +30deg. Of course that is a single case, ISTM a lot depends on how extensive the Es reflecting area is, the localised nature of many Es openings suggests that the reflecting areas are often fairly small, but some days it is like the areas are huge.

My feeling is that for the purpose of the challenge it would be better to optimise for DX and full azimuth coverage to maximise the number of chaser or activator multipliers, but for ordinary SOTA it is more a matter of what is convenient.

1 Like

Having this diagram in mind helps a bit.

I always try to adjust my endfed accordingly depending on the time of day/condx. The local conditions (seating space, open space, trees…) then determine how it is set up.

73 Armin

2 Likes

I get the same azimuth patterns you get, Marek - here’s the elevation pattern for the (1/4-wave) vertical you have modelled:

vert_10m_elev_patt

with a main lobe at 15° - 18° above horizontal.

Of course, this just shows what we all know, viz. verticals are great for all-round DX, which is why they’re so popular with DXpeditions, but they tend to be noisy due to their picking up signals from every direction.

1 Like

Hi Rob,

I take it it’s 1/4wl with 3 radials.

If so it’s interesting to see that it seems that EFHW10 (monoband) has slightly better gain and different radiation pattern. Which would give better performance at higher angles, when 10 is open, so anything is possible.

73 Marek

3 Likes