Sunday, February 3, 2019

Experimental vertical antenna - elevated radials

Vertical wire aside the mast
I got some comments on my vertical from PG0DX Henry. He told me I probabely should try to elevate the radials. It is a very good idea and I now remember that if you use ground radials you nee a lot of them to actually have good results with it. Using elevated radials will improve gain with just a few of them. Even a few cm above the ground will help. N6LF Rudy described it in a very interesting paper.



So now the practical side of the radials, the problem is "room". I can elevate the radials but not permanent since it is my garden and there are other members of the family walking there as well. It is winter now so there is not much to do in the garden so just for a experiment I have elevated the 5 radials. I'm just curious how this works.

Base of my tower

On the photo at the left you see the autotuner below the plastic bag. After all the water in the tuner last year I don't take any risks anymore. The wooden block is for separating the radials from the grounded mast.


I've been testing before sunset with a interval from about 5 minutes. So far I don't see much difference in RX but in TX it is worse except at Henry's QTH but he's also receiving with the vertical. Of course this would be normal since the vertical should be worse since the angle of radiation is too low for Europe stations. The comparisation is estimated since propagation can change in those 5 minutes.




Some comparisations:

TX  (5W)             Inverted-V    Vertical                 RX                    Inverted-V      Vertical
DL3ANK              -17               -24                        MW0GSR        -08                   -07
ES2HV                  -04               -03                       DL5ZG             -16                   -16
SM2SUM               00                -11
G3SEP                   00                -09
M0ORH                -12               -22
M0TRP                 -14               -20
SM5FOQ              +9                -03

I had to wait to late in the evening to do a DX comparisation. But unfortunately propagation was not in my favour. I didn't see much north american stations at all to compare antennas. Only one at RX and one Argentinian station.

TX (5W)          Inverted-V     Vertical                     RX            Inverted-V      Vertical
PG0DX/1          -09                -08                            K1HTV     -15                   -16
SM5FQQ          -08                +2                             LU8ENU   -22                   -23
GM0HUU          00                -08
TA4/G8SCU     -20                -08

The thing is that both antennas receive equally but TX is much more difference. Although I was not spotted at DX (say about 5000km or more). I'm not really impressed!

I'm shure a vertical does well if placed completely free or near water with much more elevated radials may be. Henry is using a vertical with 10 elevated radials. He told me he just finished a FT8 QSO to ZL with only 1W QRP on 60m. Of course thats not only the antenna but the propagation as well.


3 comments:

  1. As you know, Bas, I use verticals a lot. When we talk about elevated radials, usually this means something like 1.5-2m above ground (this usefully allows people to walk under them!) With good quality ground conditions, there is no need for more than two radials.

    For sure, you will need to run a test for a much longer period of time to get a meaningful comparison. Not sure what mode you are using for tests, but WSPR during the contest-free weekday period is the only way to gather a sufficiently large data set.

    What is the natural matching of the vertical, without the tuner? Can you show us an analyser plot? If you have to make use of the tower, a half sloper will almost certainly work better, with the added advantage that radials can be buried around the tower, rather than elevated like a spider's web!

    I have never found an inverted-V to be a satisfactory antenna in comparison to any other antenna deployed here.

    ReplyDelete
  2. Now I had a chance to read the N6LF paper. I don't think I'll save it for future reference! I'd suggest reading the ARRL Antenna Book, or 'More Vertical Antenna Classics' for a clear, considered and practical discussion on verticals, their radials, and their performance.

    ReplyDelete
  3. Hello John, of course I'm no expert in vertical antennas. Yes, elevated 2m above ground would be something. Still I think a vertical works best when free standing, no buildings with iron in it around like it is the case here. I will look into a half sloper again (have been using it many years ago on 160m with reasonable results). I've been using FT8 as test mode. Tested it various times and improvement was there when I elevated the radials, for receive that is. Not for transmitted signals. Remember that a antenna could work at one location and could be worthless at another. So far nothing beated the multiband inverted-V yet here. About the matching of the vertical without tuner, I don't know, actually it doesn't interest me much since it was intended for multiband use. Do you think a resonant antenna on 60m would do much better? I doubt it... 73, Bas

    ReplyDelete

Thanks for your comment. Bedankt voor je reactie. 73, Bas