half wave antennas not needing ground elements?

[Shockwave]

People, the difference between a 5/8 wave radiator and a .64 wave radiator is essentially meaningless. It's just juggling the slightest bit of length between the radiator and the matching inductor. Thinking this is going to make some noticeable difference in gain or take off angle is wishful thinking. You have to recognize we are talking about an antenna that has a real gain of 1.2 db over the dipole. Thinking there is any room to add even a single db more gain to this design is not realistic, much less 6 db. Just to gain 3 db here you would need to add another 21 feet of in phase radiation length to the antenna. That's a long way from the 6 inches that begin to approach out of phase radiation.

I'm also curious where the idea of accurate comparisons with two antennas at 1/2 wavelength separation comes from. The 1/2 wave and full wave separation are the two distances that provide the most interaction when phasing two antennas. I understand feeding two active elements is different and in this case it is done so that both patterns don't directly overlap. What I am saying is that I think you'd be very surprised how much interaction the second element has at 1/2 wavelength even when it's not energized and acting only as a parasitic element. If you were able to walk the "passive" antenna around in a circle at 1/2 wave distance from the "active" antenna, you would clearly see the interaction while looking at the S meter.

 

[jazzsinger]

People, the difference between a 5/8 wave radiator and a .64 wave radiator is essentially meaningless. It's just juggling the slightest bit of length between the radiator and the matching inductor. Thinking this is going to make some noticeable difference in gain or take off angle is wishful thinking. You have to recognize we are talking about an antenna that has a real gain of 1.2 db over the dipole. Thinking there is any room to add even a single db more gain to this design is not realistic, much less 6 db. Just to gain 3 db here you would need to add another 21 feet of in phase radiation length to the antenna. That's a long way from the 6 inches that begin to approach out of phase radiation.

I'm also curious where the idea of accurate comparisons with two antennas at 1/2 wavelength separation comes from. The 1/2 wave and full wave separation are the two distances that provide the most interaction when phasing two antennas. I understand feeding two active elements is different and in this case it is done so that both patterns don't directly overlap. What I am saying is that I think you'd be very surprised how much interaction the second element has at 1/2 wavelength even when it's not energized and acting only as a parasitic element. If you were able to walk the "passive" antenna around in a circle at 1/2 wave distance from the "active" antenna, you would clearly see the interaction while looking at the S meter.

i would have mentioned the parasitic effect of the second antenna .Adding the interaction of the parasitic element to the multipath phase effect and you can see improvement/degradation of signal that just doesn't exist.throw in geography and positioning of buildings you have a recipe for meaningless results.

i'm curious why you don't build .64 antennas shockwave,seeing as your a commercial antenna builder to trade?

 

[CDX-007]

People, the difference between a 5/8 wave radiator and a .64 wave radiator is essentially meaningless. It's just juggling the slightest bit of length between the radiator and the matching inductor. Thinking this is going to make some noticeable difference in gain or take off angle is wishful thinking. You have to recognize we are talking about an antenna that has a real gain of 1.2 db over the dipole. Thinking there is any room to add even a single db more gain to this design is not realistic, much less 6 db. Just to gain 3 db here you would need to add another 21 feet of in phase radiation length to the antenna. That's a long way from the 6 inches that begin to approach out of phase radiation.

I agree, in NEAR FIELD testing.

I'm also curious where the idea of accurate comparisons with two antennas at 1/2 wavelength separation comes from. The 1/2 wave and full wave separation are the two distances that provide the most interaction when phasing two antennas. I understand feeding two active elements is different and in this case it is done so that both patterns don't directly overlap. What I am saying is that I think you'd be very surprised how much interaction the second element has at 1/2 wavelength even when it's not energized and acting only as a parasitic element. If you were able to walk the "passive" antenna around in a circle at 1/2 wave distance from the "active" antenna, you would clearly see the interaction while looking at the S meter.

Ben there, done that. At ¼ wave spacing they acted as reflectors to one another and I saw the greatest (~15dB) difference to stations off the ends.

With the ½ wave spacing I saw 3dB difference, and that's possibly due as much to the null effect as any interactive reflections.

 

[Robb]

Cool down and keep to the subject please.
NO name calling or innuendos.
I'd hate to lock down an otherwise nice thread...

 

[jazzsinger]

So much for answering my question about your "Conjugate match" bring wrong.

Oh sorry, but my numbers are correct and work 'spot on'.

But lets go ahead and use your super-corrected ultra accurate superior mathematical formulas, just for grits-n-shins...
OK, I guess the 22' 4" Sigma 5/8 is resonant for...

wait for it...

wait for it...

28.9mHz! - Yeah, THERE YA GO!

But I really liked this one:

Oh, but OF COURSE, it works so well NOT because it is what it is.

Now why didn't I think of that?

your numbers are far from correct,and i'm sure you'd find conjugate matching wrong,because you probably aren't considering re-reflection.

i've provided the maths,why don't you double check it and prove me wrong,or will you just take a highly innacurate mfj or some other antenna analysers word for it?

i'm sure if i'm wrong guys like shockwave/bob 85 will disprove my maths.

 

[jazzsinger]

You know the answer to your question Jazz, they don't work as good as the Sigma design. CDX is looking at the physical lengths of all these 5/8 wave or .64 wave antennas but he's entirely overlooking how the matching network alters the electrical length of the antenna to RF. The actual electrical length of these antennas is nearly identical regardless of the physical differences. For example the only reason the Imax 2000 is 24 feet physically is because it has a series capacitor to shorten it electrically. The Maco is the shortest because it has the most inductance in the matching loop.

It was a rhetorical question,i know only too well why you build sigma design commercial antennas,and so do the companies that buy them from you.

even when he looks at the physical lengths he still gets the fraction of a wavelength wrong,but steadfastly refuses to accept FACT.

I would love him to show me any 5/8 wave or for that matter .64 wave that is physically the true length of the fraction of wavelength that it is classed as,because like you say they are made to accomodate the matching devices reactance and to overlook that fact is seriously short of sound antenna theory.

the physical length means nothing,its the electrical length which is THE only thing that matters to rf.

 

[Shockwave]

I agree, in NEAR FIELD testing.


Ben there, done that. At ¼ wave spacing they acted as reflectors to one another and I saw the greatest (~15dB) difference to stations off the ends.

With the ½ wave spacing I saw 3dB difference, and that's possibly due as much to the null effect as any interactive reflections.

Everything I work with involves far field as it's the only thing that increases my clients range. The only way to pick up a db over the 5/8 wave with a single element is to use the Sigma design. With respect to the separation at 1/2 wave, having a 3 db change in any direction is a huge variable when the actual difference between antennas could be no more then tenths of a db.

 

[CDX-007]

Shockwave, the antennas were NOT firing off the ends, not even a couple degrees in the direction of my test station, that's why I set them at that position.

Off the ends +/-3Db, but perpendicular to the plane of elements there is zero phase interaction. I've built enough repeaters to have already found this true, whereas simultaneously driven antennas cancel off the ends ~20dB but show +3dB gain in the perpendicular direction / off the sides.
This is no secret.

Originally Posted by CDX-007
So much for answering my question about your "Conjugate match" BS.

Oh, sorry pal, but my numbers are correct and work 'spot on'.

But lets go ahead and use your super-corrected ultra accurate superior mathematical formulas, just for grits-n-shins...
OK, I guess the 22' 4" Sigma 5/8 is resonant for...

wait for it...

wait for it...

28.9mHz! - Yeah, THERE YA GO! Wow, what a genius!

- More like a spin king.

But I really liked this one of yours best:

i don't doubt your penetrator works well,i do doubt it is because its .64 wave though.

Oh, but OF COURSE, it works so well NOT because it is what it is.

Now why didn't I think of that? You're such a genius!

your numbers are far from correct,and i'm sure you'd find conjugate matching BS,because you probably can't get your head round rereflection.

i've provided the maths,why don't you double check it and prove me wrong,or will you just take a highly innacurate mfj or some other shitty antenna analysers word for it?

i'm sure if i'm wrong guys like shockwave/bob 85 will disprove my maths.

What, trust an MFJ 259B to read correctly, naw, they make them to read as far off as possible, and I'm certain that when it shows X=0 it absolutely must, HAS TO BE, wrong. Why? - Because YOU say so, of course.

I'm so laughing at myself, red faced but finding it ironic that I reverse calculate the velocity factor in a post attacking his math, and no one even realizes it!! :blush:

I've owned, rebuilt and assembled enough 5/8 & .64 omnis to know there's nearly ZERO difference in their (respective) radiator length, especially when setting for X= 0.
If the MACO were just another 5/8 then why is it down at least a full S-unit in comparison to a real 5/8 or .625? - This has been found to be true over and over again.

Anyway, Jazz, yes your math still stinks.
22' 4.5" - That's the Sigma 5/8 radiator length, 268.5"

Divided by .95 (Your alleged 'aluminium' velocity factor, slower than balanced line, but hey... ) brings us a radiator now 'electrically' 282.63" making it resonant on 26.1mHz
(11803 ÷ 282.63 = 26.1)
Gee, only 1.1mHz below center of band, 27.2mHz where it was designed to work. Oh what the heck, what's a meg or two between meters...
Right, sure, absolutely where I'd design an antenna for CB... - NOT.

OK, now let's look at the I-10K.

212" + "V7" (top piece of radiator element length found in I-10K chart provided with antenna) of 44.25" for 27.2mHz at X= 0 both on my mast and according to the chart given with the I-10K, plus the 12" top hat, for a total length for this completely different matching network 5/8 antenna of:
212"+44.25"+12" = 268.25"
...amazing how those two completely different matching networks can have exactly the same length radiator (within .25") on two completely different 5/8 'type' antennas with such different matching networks which have different matching networks needing so very different radiator lengths with such different matching networks ...ad nauseum.

Hey jazzsinger, "Who'd uh thought, eh?"

- Mind boggling, you'd think they would be totally different lengths due to such "Different matching networks" and the I-10K being of course so much more efficient and all...
Silly me thinking a 5/8 is a 5/8.

I guess all I can do is measure.

Yeah, they just HAVE to be so different physically, it's only the "Electrical length that matters" so there certainly can be no antenna which measures correctly, (taking the K factor into account of course) nope, they all HAVE to be like really really way too long or really really way too short to work as the same 5/8 with these extremely different matching networks, yup, uh huh, you bet!

-----------------

Oh, FYI Jazzsinger, the reason I tried out the 5/8 I-10K was with the hope their claims of other-worldly incredible efficiency had merit.

And don't even begin to try to say you haven't read the same claims and links to claims that we have all seen and read stating, '...Several S-units better than my old 5/8 - Penetrator' and the like...

Leave it to someone like you to spin it into something it never was, or have you already forgotten what you wrote:

I do truly dig the Penetrator 500 BECAUSE it holds it's own to this day, not because I imagined it, and Jazzsinger, I was truly hoping the I-10K would trounce the Penetrator, that would mean I would have found a way to get BETTER performance. Saying I'm only being nostalgic is ridiculous. That's discounting everything I've measured in favor of some ancient aluminum-love affair.

what really surprises me is you have so much faith in .64 antennas yet you truly hoped a 5/8 wave trounced it,hmmm,do i detect contradiction/lack of faith of your own belief.

nostalgia very often over rules common sense.

I already understand how/why people of your ilk tend toward such argumentative spin attacks, I grew up with one.

Oh, and what about your ad hominem attacks on 1342 and me, someone I've never even had PM correspondence with... my ".64 Pal" huh?

Yeah, I'm sure the hordes and throngs of your faithful followers (in your mind)

are awaiting your next fallacious declaration "with great eagerness".


- I notice your signature contains a high-reading BS meter at the bottom of your posts.Excellent placement!

...Freudian, no doubt.

 

[Shockwave]

If the Maco V-58 is down 6 db from other 5/8 waves tested I would say the people testing them had as many unexpected variables as the setup you photographed. If a little extra length could add 1 S unit to the V-58 Tom Charles would have done it after all this time. Just because a particular spacing provides enough rejection for a repeater to function correctly in no way indicates you have eliminated the interaction between the two antennas to the point where an accurate comparison can be made.

While it's fairly easy to predict the pattern of two identical antennas driven together at a known phase angle, it's not so cut and dry when they are different antennas and one is left as a parasitic element. Here are a few variables to reconsider. Since the parasitic antenna is not excited trough it's matching network physical variations in it's design can cause it to reflect or direct RF. How about the coax length and if it happens to be reflecting a short or an open back to the antenna not in use?

These things can destroy signal comparisons, alter the impedance of the driven antenna and skew the expected pattern. You can't assume that the affects of the second antenna will only be seen in one axis and that the opposite directions will remain unaffected to within the few tenths of a db change you are looking to measure in the first place. If you're serious about determining the differences between two antennas, this is not the way to arive at an accurate conclusion.

The last argument about radiator length and matching networks didn't make a bit of sense because you took the facts out of context by reversing them to try and support your thoughts. Two completely different matching networks can be designed to transform the same exact impedance. Meaning they could easily match the same length radiator. What was being said is if the radiator lengths are different, then the matching networks are different to compensate for that. By the way, 12 inches of top hat does not equal 12 inches of extended radiator length.

 

[CDX-007]

If the Maco V-58 is down 6 db from other 5/8 waves tested I would say the people testing them had as many unexpected variables as the setup you photographed. If a little extra length could add 1 S unit to the V-58 Tom Charles would have done it after all this time. Just because a particular spacing provides enough rejection for a repeater to function correctly in no way indicates you have eliminated the interaction between the two antennas to the point where an accurate comparison can be made.

While it's fairly easy to predict the pattern of two identical antennas driven together at a known phase angle, it's not so cut and dry when they are different antennas and one is left as a parasitic element. Here are a few variables to reconsider. Since the parasitic antenna is not excited trough it's matching network physical variations in it's design can cause it to reflect or direct RF. How about the coax length and if it happens to be reflecting a short or an open back to the antenna not in use?

These things can destroy signal comparisons, alter the impedance of the driven antenna and skew the expected pattern. You can't assume that the affects of the second antenna will only be seen in one axis and that the opposite directions will remain unaffected to within the few tenths of a db change you are looking to measure in the first place. If you're serious about determining the differences between two antennas, this is not the way to arive at an accurate conclusion.

The last argument about radiator length and matching networks didn't make a bit of sense because you took the facts out of context by reversing them to try and support your thoughts. Two completely different matching networks can be designed to transform the same exact impedance. Meaning they could easily match the same length radiator. What was being said is if the radiator lengths are different, then the matching networks are different to compensate for that. By the way, 12 inches of top hat does not equal 12 inches of extended radiator length.

Whatever you say.

I bet you just helped sell a thousand more $125 Maco V-5/8s over that $339 I-10K, after all, they're both just 5/8 waves.

 

[1342]

Whatever you say.

I bet you just helped sell a thousand more $125 Maco V-5/8s over that $339 I-10K, after all, they're both just 5/8 waves.

hello my .64 pal lol.i have owned several antennas and one thing seems to always hold true the longer of them always seems to work better with exception to the astroplane that seemed to work better than my shitduster!i have had the p-500,shitduster,asstron 99,midland 5/8,maco 5/8 and the imax 2000 plus homebrew loops and dipoles.i sadly got rid of the p-500 years ago but have the imax up now with 102 top whip and the gpk off my maco 5/8 and even though my imax 2000 is 5 feet longer than my maco well shock says the maco is better so!forget about those guys in canada that could not here me on the maco because what shockwave says goes.forget about the fact that they were both at the same height with the same belden 9913 and the same mast and forget about the fact that these guys are between 90-120 miles away from me and forget that i swapped these antennas out in 20 minutes time to come to my conclusions and forget about that extra 5 feet of height and capture area you know why because shock says so!and seems contradicting but he just stated the sigma would work better hmm thats longer go figure so a longer antenna works better unless they say so wow.

 

[BOOTY MONSTER]

assuming the 6 inch difference between a 5/8 and .64 makes a detectable diference .......
since the radiating wire in the top section of the .64wl imax is 96.5 inches long shouldn't replacing it with a 102 inch radiator take it beyond the optimal length for TOA and lobe dispersion and actually reduce its performance ?

another question . the .95velocity factor for aluminum doesn't take into account the diameter of the radiator being used . doesn't the diameter of the radiator affect its length too ? shouldn't my 1 inch to 1 3/8 inch vertical be slightly shorter for a particular wavelength than a wire made of the same material ?

 

[jazzsinger]

another question . the .95velocity factor for aluminum doesn't take into account the diameter of the radiator being used . doesn't the diameter of the radiator affect its length too ? shouldn't my 1 inch to 1 3/8 inch vertical be slightly shorter for a particular wavelength than a wire made of the same material ?

i used an average vf for aluminium to highlight lack of it,in reality depending on other variables it may be a percent or two either side.

the point i was making was the vf was missing altogether in other experts calculations,but like most things in antennas there is variables dependent on materials used,location etc,like radiator lengths being adjustable to take into account impedance changes due to surrounding objects,thats why all decent antennas are tuneable and not preset.

in answer to your first point on the 102 inch whip,i can only assume this extra 5.5 inches brought a further 6db gain going by previous statements,

 

[HomerBB]

Excuse me, but has it been decisively decided yet whether half wave antennas need ground elements or not? I thought it had, then I thought it hadn't, then I didn't know what to think . . .

 

[Shockwave]

hello my .64 pal lol.i have owned several antennas and one thing seems to always hold true the longer of them always seems to work better with exception to the astroplane that seemed to work better than my shitduster!i have had the p-500,shitduster,asstron 99,midland 5/8,maco 5/8 and the imax 2000 plus homebrew loops and dipoles.i sadly got rid of the p-500 years ago but have the imax up now with 102 top whip and the gpk off my maco 5/8 and even though my imax 2000 is 5 feet longer than my maco well shock says the maco is better so!forget about those guys in canada that could not here me on the maco because what shockwave says goes.forget about the fact that they were both at the same height with the same belden 9913 and the same mast and forget about the fact that these guys are between 90-120 miles away from me and forget that i swapped these antennas out in 20 minutes time to come to my conclusions and forget about that extra 5 feet of height and capture area you know why because shock says so!and seems contradicting but he just stated the sigma would work better hmm thats longer go figure so a longer antenna works better unless they say so wow.

Yes of course, back to the more capture area the more signal. So if adding some length gains 1 S unit, lets add twice as much length for 2 S units. Ignore the fact that once the radiator goes electrically beyond 5/8 wavelength that extra length is now radiating out of phase. If you refuse to recognize how the matching networks alter the electrical length of the antennas, I can't make you see it. I'm not saying you will never see any difference between these antennas. I am saying you will never see anything close to an S unit change between any two base CB omni antennas. There have NEVER been two CB base omni antennas manufactured that have a difference in gain of 6 db or 1 S unit.

You have to love the analogy that because the Sigma works better then a 5/8 wave it's only because it's longer. So why not just make a 29 foot 5/8 wave? It has to be that capture area with the Sigma and not the fact the tapered transmission line cone keeps the radiated energy in phase. More understanding of how RF radiates in relation to phase angle and radiator length would be helpful to you. This reminds me of the guys 30 years ago replacing the 96 inch fiberglass whip on the Big Stick antennas with a 102 inch steel whip saying it made a big difference.

CDX, I bet you were surprised when you got your coax issue sorted out and found the old $80 Hy-Gain 5/8 wave had the same results as the $339 I-10K. I've said it before and I'll say it again. The properly designed 5/8 wave has 1.2 db gain. It's not possible to add even a single db to that figure regardless of what you do with radiator length or matching networks.