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End Fed 1/2 Wave Vertical
- Thread starter RickC.
- Start date
Right! I have no earthly idea what the RF voltage is up there. I'd still try the solid dielectric if I had some to spare. But today I got the open wire matching section built- 14 ga solid spaced 1.5 inches. When this cold windy spell blows out of here later in the week I'll get it connected and tuned, and we'll see what she does.
Keep in mind, that's 40KV DC. RF just might be a little different.
True indeed.
The AC capability would only be about 70% of 40 kv assuming a sinewave.
Assuming antenna feed impedance of 5000 ohms using P = V squared / R with 1000 watts the voltage will be 3152 volts.
Ok- It's now a J-pole. The homebrew open line was too heavy to support its own weight and the feedline attachment without touching the roof (and there was no place to make a standoff support). So I just turned the matching section 90 degrees and ran it straight down the wooden pole with the feedpoint maybe 2 feet off the ground.
With the coax attached 11" from the shorted end VSWR is under 2:1 for the whole band, under 1.5:1 to one for most of it-- going above 1.5:1 at 14335, but I seldom operate that high in the band anyway. It was getting dark so I declared a victory and left it at that.
This is Plan C for this wire, we'll see how it does.
Rick
With the coax attached 11" from the shorted end VSWR is under 2:1 for the whole band, under 1.5:1 to one for most of it-- going above 1.5:1 at 14335, but I seldom operate that high in the band anyway. It was getting dark so I declared a victory and left it at that.
This is Plan C for this wire, we'll see how it does.
Rick
A short update.
I haven't been able to spend a lot of time on the air the past week due to work demands, but what openings on 20 to Europe there have been have turned up some interesting results.
The feedpoint of the j-pole is about two feet off the ground, with the radiating half wave still where it was, above the roof and in the clear. Now this is just the dreaded anecdotal report, but in contacts with EI, 2I, ON, EA8, and M0 (some of which lasted as long as 20 minutes), I could tell very little difference on receive between the j-pole and a dipole at 35', situated to where Europe is off the ends of the dipole. Yet, on the distant station, the j-pole was consistenly 2 S units above the dipole, occasionally 3. On some other contacts to SA and the Caribbean, the j-pole was significantly better on both transmit and receive, on others there was no difference.
At times the J-pole had higher noise than the dipole, at other times it was just the opposite, so there goes the idea that a vertical is always noisier. I know from having the yagi up earlier that the intermittent power line noise I have is coming from the south, and that is always stronger on the horizontal antenna.
I'll keep playing as I have time and keep taking notes. What I expected was the j-pole to kill the dipole on DX contacts off the end of the dipole, and it does do that.
Sometimes.
Rick
I haven't been able to spend a lot of time on the air the past week due to work demands, but what openings on 20 to Europe there have been have turned up some interesting results.
The feedpoint of the j-pole is about two feet off the ground, with the radiating half wave still where it was, above the roof and in the clear. Now this is just the dreaded anecdotal report, but in contacts with EI, 2I, ON, EA8, and M0 (some of which lasted as long as 20 minutes), I could tell very little difference on receive between the j-pole and a dipole at 35', situated to where Europe is off the ends of the dipole. Yet, on the distant station, the j-pole was consistenly 2 S units above the dipole, occasionally 3. On some other contacts to SA and the Caribbean, the j-pole was significantly better on both transmit and receive, on others there was no difference.
At times the J-pole had higher noise than the dipole, at other times it was just the opposite, so there goes the idea that a vertical is always noisier. I know from having the yagi up earlier that the intermittent power line noise I have is coming from the south, and that is always stronger on the horizontal antenna.
I'll keep playing as I have time and keep taking notes. What I expected was the j-pole to kill the dipole on DX contacts off the end of the dipole, and it does do that.
Sometimes.
Rick
Rick,
I think what you are seeing is fairly normal for horizontal/vertical polarization differences, and not really all that unusual. There are a few things that are just factual, like verticals being 'noisier' than horizontally polarized antennas. That certainly doesn't mean that they are always going to be the least desirable of the two antennas. Lots of it has to do with propagation. Sounds like a 'cop-out' but it isn't, there are always variations of 'normal', in just about anything I can think of except taxes (yeah, nasty, I know, but still...).
One aspect if you didn't think of it, is the 'over the poles' propagation thingy and that dipole. What you were hearing may not have been off one end of that dipole, but a polar route. No idea if that's what was happening, but it's a possibility, right?
How about another one? As in, that 'J' pole's feed point being a couple of feet off the ground. Ground mounted verticals really do work, no matter if they use radials in dirt, or that 'J' pole's counterpoise.
Oh well, who cares. It's fun, ain't it?
- 'Doc
I think what you are seeing is fairly normal for horizontal/vertical polarization differences, and not really all that unusual. There are a few things that are just factual, like verticals being 'noisier' than horizontally polarized antennas. That certainly doesn't mean that they are always going to be the least desirable of the two antennas. Lots of it has to do with propagation. Sounds like a 'cop-out' but it isn't, there are always variations of 'normal', in just about anything I can think of except taxes (yeah, nasty, I know, but still...).
One aspect if you didn't think of it, is the 'over the poles' propagation thingy and that dipole. What you were hearing may not have been off one end of that dipole, but a polar route. No idea if that's what was happening, but it's a possibility, right?
How about another one? As in, that 'J' pole's feed point being a couple of feet off the ground. Ground mounted verticals really do work, no matter if they use radials in dirt, or that 'J' pole's counterpoise.
Oh well, who cares. It's fun, ain't it?
- 'Doc
Sure is, Doc!
And you may be right about the polar thing, who knows?
What was strange to me (and I guess I didn't say this very well) is with the Irish and English stations, the j-pole had a 2-3 S unit advantage over the dipole on transmit but not on receive.
Over the years I've had yagis, quads, delta loops, and a bunch of dipoles/inverted vees and verticals-- oh, and one Moxon. Of them all, my favorite array was a pair of phased ground planes for 20 meters. The feedpoints of both of them was only up 18 feet, but that was a very effective array, cheap, and fun to use. If I had room for them now I'd put up another pair (or maybe 4).
Rick
And you may be right about the polar thing, who knows?
What was strange to me (and I guess I didn't say this very well) is with the Irish and English stations, the j-pole had a 2-3 S unit advantage over the dipole on transmit but not on receive.
Over the years I've had yagis, quads, delta loops, and a bunch of dipoles/inverted vees and verticals-- oh, and one Moxon. Of them all, my favorite array was a pair of phased ground planes for 20 meters. The feedpoints of both of them was only up 18 feet, but that was a very effective array, cheap, and fun to use. If I had room for them now I'd put up another pair (or maybe 4).
Rick