I would imagine the 1/2 wave horizontal radials would dominate the pattern over the radiator, but I'll try it.
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End Fed 1/2 wave antenna
- Thread starter HomerBB
- Start date
I would imagine the 1/2 wave horizontal radials would dominate the pattern over the radiator, but I'll try it.
the choke is just below the bottom end of the mast,
i just spoke to him again and something went tits up, he's got tv remote with just 4w when 100w did nothing to the tv for a few days, i don't know what he changed until i see it
i just spoke to him again and something went tits up, he's got tv remote with just 4w when 100w did nothing to the tv for a few days, i don't know what he changed until i see it
Sounds to me like some alterations in the modulation, or maybe changed some jumpers out and has some bleeding jumpers/connections . . .
Here is the A99 with 210" vs. 72" radials. The 210" radials cancel out and appear to suck the current out of the radiator as they dominate being so long.
View attachment NB's idea for .50 wave radials..pdf
View attachment NB's idea for .50 wave radials..pdf
I experienced the same thing Bob, one day the choke appeared to work fine then it just seemed to stop working. I never was able to explain why.the choke is just below the bottom end of the mast,
i just spoke to him again and something went tits up, he's got tv remote with just 4w when 100w did nothing to the tv for a few days, i don't know what he changed until i see it
Homer if your EFHW has a variable capacitor, within reason you could vary the length of the radiator and still tune the match. I think the Yates article I posted has some discussion on such.
Have you tried testing that idea with your 259B?
Have you tried testing that idea with your 259B?
NB, I posted your idea if I understand it correctly. What were you expecting?
Which 7 was it, Marconi?
I may try what you say, but the dial in for a good match isn't as easy as it's said.
When I've fished around for the match just a little movement with the cap sends things scooting off pretty good.
The antenna has behaved fairly resonance sensitive, too, I've thought, so I am not so sure changing the length can be so readily remedied by cap adjustment. I am meaning that when the antenna length is good for 10 meters that's where the match wants to settle in, and if I'm overly long for CB band, it drops down lower on the band with the match.
When I get something else to talk on in the air I may try it.
If the weather holds tomorrow I may stick a dipole up and play with the cap on the half wave some . . . maybe.
I may try what you say, but the dial in for a good match isn't as easy as it's said.
When I've fished around for the match just a little movement with the cap sends things scooting off pretty good.
The antenna has behaved fairly resonance sensitive, too, I've thought, so I am not so sure changing the length can be so readily remedied by cap adjustment. I am meaning that when the antenna length is good for 10 meters that's where the match wants to settle in, and if I'm overly long for CB band, it drops down lower on the band with the match.
When I get something else to talk on in the air I may try it.
If the weather holds tomorrow I may stick a dipole up and play with the cap on the half wave some . . . maybe.
I don't want you to mess up your settings either just to find out... That bugger was quieting my radio real nice when we talked, and again I was impressed with how well a 1/2 wave can work.
Frankly, I sometimes think we just make too much over the true characteristics of these bigger antennas. At least to an extent, unlike our buddy on the WWDX forum, KingCobra_CDX882, who claims that everyone who hears him on his I-10K...always swears he's on a 5 element beam or bigger. Homer, sorry to say, I couldn't tell that with your half wave however.
Testing the capacitor on a 1/2 wave for such responses would be easier and probably a lot more dependable since you will be working with a more reasonable match. You might even be able to do it horizontal, and stretch it out to a 5/8 wavelength or near and still get it to tune in close to CB. Just don't waste too much time trying to get too aggressive, OK?
Keep us posted, I like testing these theories when possible. I just wish I wasn't so old and weak in body.
I was just curious to see what effect it would have to mirror the 1/2 wave radiator with 1/2 wave radials at 90° out of phase.
Were they isolated from mast, coax & ground?
So Marconi, after all these models and posts, if you were to scrap & sell off all your antennas, what would you choose for your only omni with what type of matching network and radials/no-radials set up?
I'm of a mind that the Vector works as an active 1/2 wave with a relatively efficient matching network beneath it elevating it above a 1/4 wave null above the mast, and an end-fed 5/8 acts as a 3/8 active radiator also elevated above a 1/4 wave null above the mast & radials.
The Vector, then, should have 33% more effective radiator over the end-fed 5/8 & another 1/8 wave in elevation, providing some gain, about 1dB, whereas the Gainmaster offers 66% more effective radiator over the end-fed 5/8 for around 1.5dB gain.
I've figured out a way to test & prove whether or not the Vector radial basket actually radiates- adding gain as a colinear.
After I set up the test jig I'll post the test & results on youtube to quiet that issue forever.
I really don't see how you can have a better single-element antenna than a low loss matched elevated 1/2 wave, since that's radiating the full in-phase 1/2 cycle at a lower angle, except for the Gainmaster stretching the middle out, adding another 1/8 wave of active radiator and in-phase current to it's current bubble, which I feel is truly ingenious and why it should be the best performing single-element omni there is.
Interesting that a 3/4 wave has even more near field gain but an atrociously high angle and it's basically an active 1/4 wave elevated over a 1/2 wave null instead of over a 1/4 wave null like both the better performing Vector/Sigma4 & end-fed 5/8 wave designs. The one with the high TOA is over a 180° null, the others with the low TOA are over a 90° null. hmmm
The way I see it:
1/4 wave = high angle 1/4 wave (-3dB Near Field)
1/2 wave end fed = medium-high angle 1/2 wave (0Db NF)
Center-fed 1/2 wave dipole = lower angle 1/2 wave (0dB NF)
5/8 end fed = elevated low angle 3/8 wave (+2Db NF)
Vector/Sigma4 = elevated low angle 1/2 wave (+3Db NF)
Gainmaster = lowest angle full 5/8 wave (+3.5Db NF)
Ultimately I have seen much greater gain results further out, as much as several s-units difference between 1/2 wave & an end-fed 5/8 or a Gainmaster, even though at near field there's not as much difference.
:bdh:
Needlebender, clearly you are more versed than I am with all this. I'm just a boy scout . . . However, I fail to see how you come up with the Sigma/Vector as a 1/2 wave in the above post. I must have missed something.
I guess what you heard Simon say was take BIG steps ???
I guess what you heard Simon say was take BIG steps ???