Inverted V made longer and now...

I am seeming to get an odd antenna pattern. If you look up calls received by me on pskreporter, I appear to have created quite the deadzone for 20M. 40M, 30M, hell, even 10M seems to work reasonably well, but check out how it appears on 20:

https://www.pskreporter.info/pskmap....id=1&showsnr=1

So, I added about 15 ft to one leg, and 8 ft to another leg of the V (Due to yard size/shape, and feedpoint placement), so I understand I have a bit of a random-wire OCF going. Before the lengthening, I was getting reasonable performance on 40, great perf on 20, and nothing on 10M.

Is this just a fact of life with OCFs?

I'm using an original Fritzel OCF 80-10, and used a dipole before.
The only difference is the feed point difference, the balun and 1:1 after that, it is just a dipole fed out of center.
Depending on how high the antenna is situated for that frequency you can pick a low hanging antenna and have Straight up radiation or NVIS, or if you get over 1/4 wave of the frequency above ground the anntenna starts to lower the radiation and behave more as a dipole.

If the antenna is reasonably low as in my case, 40 feet above good ground, it works in all directions, for 10 meter where it is more as a wavelength above ground it is a pure dipole, With noticeably east west lobes.( strung North/south)

NVIS will be good for working the stations up to 1500 KM's but is bad for DX.
The opposite goes for the dipole at a full wave above ground, good for DX, worse for stations in your area.
Reason i use the 160 inverted L also on 80 - 10 to fill in the pattern.
You have the radiating elements in V form, so there will be some DX possible as well NVIS.
Which shows in your report, Europe and the USA, depending on the hops there will be dead zones, we all have them, so it is better to have dedicated antenna's for what you want to do at that moment.
At 40 meters my dead zone is the UK, ( part of it) Ireland which is just a tad further is excellent, so my dead zone is 200 - 300 miles away for the first hop on 40, which the inverted L will fill in very nicely.

For 80/40 i have a nice NVIS Europe antenna, 20 - 10 it is better for DX.
My inverted L, now back to a 23 meter vertical with autotuner feeding it at the feed point is having a lower radiation pattern, longer hops good for dx but filling in some of the "dead" zones of the dipole.
Though its length above 17 the radiation pattern is a bit awkward though....it just depends where the lobes are pointed to at that frequency, but then i also use a IMAX 2000 that works fine on 17 - 10 meters on the roof.

My experience for what my 2 Euro cents are worth, there is not one antenna that does it all, there are antenna's that radiate in all directions equally bad though ;)
Verticals are not used a lot, even a long wire up in a tree with tuner feeding it directly as in my case, can certainly surprise you.

I have a wealth of antenna books, but there is only one way to find out what works for you, experiment with your stuff, on your plot of land and in the possibilities you have there to string up a piece of wire.
Conditions for you and me might differ a lot, i'm on the edge of the city, on rich young sea clay good ground.
That might be totally different for you and so the antenna will behave totally different at your place as mine.
Simple rule i have, the more copper in the air as high as you can get it, mostly also gets the job done.

I mostly run 100 - 200 watts here from the Yaesu FT 2000 - D, and only use the Heathkit SB-1000 on 160 meters.
Hope it helps....

What were the wire lengths before you added the 8 and 15 foot sections?

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Originally Posted by KJ3N

What were the wire lengths before you added the 8 and 15 foot sections?

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20'ish feet. Wasn't particularly specific, because I was using the wire I had on hand, and wanted something in the air, and it's fed with balanced line into a tuner. I can actually measure it specifically this weekend, and probably will, as it'll likely answer my own question (ie, "Dur, you're trying to load up a 1000 ohm load!")

Quote:

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Originally Posted by KC2UGV

20'ish feet. Wasn't particularly specific, because I was using the wire I had on hand, and wanted something in the air, and it's fed with balanced line into a tuner. I can actually measure it specifically this weekend, and probably will, as it'll likely answer my own question (ie, "Dur, you're trying to load up a 1000 ohm load!")

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I don't think this is a load issue. As long as the tuner can match it, it doesn't really matter.

My guess is that you've skewed the pattern with the unequal lengths of wire. With my limited understanding of EZNEC, it appears that the pattern is skewed towards the longer wire.

On 20m, here's the pattern based on 20 feet per side, looking down from space:

Attachment 15282

Here's the pattern with 35 feet on one side, and 28 feet on the other:

Attachment 15283

The elevation plot also changes.

20 feet per side:

Attachment 15284

35 feet one side, 28 feet on the other:

Attachment 15285

Yeah, that would make sense too... Almost like a shotgun mic. The elevation profile looks like the explains the much large skip region as well.

That ain't a bug...it's a feature.

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Originally Posted by N8YX

That ain't a bug...it's a feature.

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I can see some benefits with the current antenna: Right now, by switching between 40 and 20, I've got the entire US covered. 20M is noisier than before, but workable. 40 comes in hot, all hours of the day. Got to set this for 30M to see how it works there for a day or two now.

:popcorn:

Quote:

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Originally Posted by KC2UGV

I am seeming to get an odd antenna pattern. If you look up calls received by me on pskreporter, I appear to have created quite the deadzone for 20M. 40M, 30M, hell, even 10M seems to work reasonably well, but check out how it appears on 20:

https://www.pskreporter.info/pskmap....id=1&showsnr=1

So, I added about 15 ft to one leg, and 8 ft to another leg of the V (Due to yard size/shape, and feedpoint placement), so I understand I have a bit of a random-wire OCF going. Before the lengthening, I was getting reasonable performance on 40, great perf on 20, and nothing on 10M.

Is this just a fact of life with OCFs?

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What band is the antenna optimized for ? What type of feed-line are you using ? What type of tuner ? For decades I used an inverted vee cut for 75-80 m. I fed it with open wire line and used a old style Johnson Matchbox (link coupling) and I got incredibly great performance on 80-20m. There was some "directionality" to it , I got better results North- South than East /West but that's the nature of the beast. But I always had a very respectable signal (to put it mildly) and even busted through a few pileups on the rare occaision when the DX-ing bug bit me. The feed point should be as high as you can get it (pref 60-70+ feet) and the ends should be 20 feet above ground level. Balanced line and a good tuner made a big difference. Coax and baluns degraded performance considerably.

Quote:

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Originally Posted by n2ize

What band is the antenna optimized for ? What type of feed-line are you using ? What type of tuner ? For decades I used an inverted vee cut for 75-80 m. I fed it with open wire line and used a old style Johnson Matchbox (link coupling) and I got incredibly great performance on 80-20m. There was some "directionality" to it , I got better results North- South than East /West but that's the nature of the beast. But I always had a very respectable signal (to put it mildly) and even busted through a few pileups on the rare occaision when the DX-ing bug bit me. The feed point should be as high as you can get it (pref 60-70+ feet) and the ends should be 20 feet above ground level. Balanced line and a good tuner made a big difference. Coax and baluns degraded performance considerably.

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Haven't measured it, and no analyzer (yet), so not really sure what it's optimized for. It does, however, appear optimized for 40M :) Being fed with 300 Ohm twinlead, into an MFJ-917 tuner.