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quad reflector versus yagi reflector

It doesn't, and no one said parasitic elements changed the velocity factor of the driven element. Yet the self resonant length of the driven element does change when parasitic elements are added to the antenna. This is because the parasitic elements load the driven element with capacitance.


The DB
I didn't find this to be true, possibly because any theoretical additional capacitance of the smaller-than-resonant parasitic director element may have theoretically been offset by the theoretical inductance of the larger-than-resonant parasitic reflector element.

Any additional system capacitance induced by adding parasitic elements was evidently cancelled since any change in resonance due to capacitive coupling was not apparent during my build, and is (I theoretically suppose) why I found no need for changing the length of the driven element away from it's resonant length to some other theoretical & evidently non-resonant length.

...or perhaps I was simply blessed with the luxury of ignorance as all I knew was that I was going to build a Quad and it was going to work, and work it did, kickin' royal arse in spite of all the God like theorist nay-sayers.
 
I didn't find this to be true, possibly because any theoretical additional capacitance of the smaller-than-resonant parasitic director element may have theoretically been offset by the theoretical inductance of the larger-than-resonant parasitic reflector element.

It doesn't work that way. While it is true that a long element does appear inductive bringing such element into the field of the driver element does not introduce inductance that can be offset by the capacitance that appears in a short element. ANYTHING brought into the near field of a driver element (or any element really) will introduce capacitance and only capacitance just the same as if the two elements were plates of a capacitor. This can be another element, a mast, or even a human body. No inductance is introduced at all.
 
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It doesn't work that way. While it is true that a long element does appear inductive bringing such element into the field of the driver element does not introduce inductance that can be offset by the capacitance that appears in a short element. ANYTHING brought into the near field of a driver element (or any element really) will introduce capacitance and only capacitance just the same as if the two elements were plates of a capacitor. This can be another element, a mast, or even a human body. No inductance is introduced at all.

Theoretically, you might have some good points, but my post stands, none such was apparent during my successful real-world build, alleged theory aside.

As I added first the Reflector, then the director(s) the center frequency remained stable though the SWR dropped as parasitic elements were added, then when satisfied that the front to back was maximized, I added the matching feedline as I recall, finding the lowest SWR point - and then I used it & loved it.
 
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Needle Bender, I love it when you think your experience is the end all and be all of what does and doesn't work, especially when people have experiences that directly contradicts yours, at which point you start calling said people idiots. That hasn't happened in this thread yet, but I don't think we are far off of that point.

The so called "alledged theory", the wording of which shows you know less than nothing about something that has been proven right time and time again, says what you are talking about will happen in some conditions, and in other conditions something else will happen. Can you honestly say with what little testing you have done that you have covered every possibility with these antennas?

It is interesting that you take what we "God like theorist nay-sayers" are saying when it agrees with what you think you are saying, but then trash us when we don't automagically agree with you on other topics. With all due respect, if anyone here is acting like they have godlike knowledge that is never to be questioned by anyone, it is you.

I will happily take the naysayer title you are putting forth and wear it as a badge of honor. Although, strangely, I don't actually meet the definition of the word...


The DB
 
Needle Bender, I love it when you think your experience is the end all and be all of what does and doesn't work, especially when people have experiences that directly contradicts yours, at which point you start calling said people idiots. That hasn't happened in this thread yet, but I don't think we are far off of that point.

The so called "alledged theory", the wording of which shows you know less than nothing about something that has been proven right time and time again, says what you are talking about will happen in some conditions, and in other conditions something else will happen. Can you honestly say with what little testing you have done that you have covered every possibility with these antennas?

It is interesting that you take what we "God like theorist nay-sayers" are saying when it agrees with what you think you are saying, but then trash us when we don't automagically agree with you on other topics. With all due respect, if anyone here is acting like they have godlike knowledge that is never to be questioned by anyone, it is you.

I will happily take the naysayer title you are putting forth and wear it as a badge of honor. Although, strangely, I don't actually meet the definition of the word...


The DB
Cool, you enjoy your theory, denigrating accusations and outright untruths and I'll enjoy my real-world RF Monster Quad antenna which outperformed every Yagi & Quagi in the area - according to THEM.

And I don't recall ever using the term idiots. My use of the term "Gods" was with reference to the book writers, not you Sir. :)

...just burned out on being told that what performed in an OUTSTANDING manner in the real world, wasn't poop according to theory.
I'd rather help someone build one than repeatedly argue why it will or won't work.
 
NB
Back in the early 80's armed with only a vswr meter & signal meter how did you measure "resonance" to determine that only impedance at the feedpoint changed as you added the parasitic elements ?
 
NB
Back in the early 80's armed with only a vswr meter & signal meter how did you measure "resonance" to determine that only impedance at the feedpoint changed as you added the parasitic elements ?

OF course it was measured with a theoretical analyzer that some electrical engineer theoretically developed for a distributor to sell to un-theoretical experimenters to prove their real world antennas defy the laws of physics based on real world testing in the back yard with a cooler full of adult beverages.

Theoretically the more adult beverages consumed the better the said real world theoretically built monster quad became the KILLER QUAD and outperformed any theoretical antenna in the past present and future, Theoretically that is.

NB you built the antenna, good on ya,, if it is so damn good apply for a patent and sell the thing to the public. Make a fortune, Theory is theory, proven by mathematical equations.

No one can change the lays of physics, I do not care how anything was built the laws of physics apply.

Shit rolls down hill and it is getting DEEP in this thread.
 
Cool, you enjoy your theory, denigrating accusations and outright untruths and I'll enjoy my real-world RF Monster Quad antenna which outperformed every Yagi & Quagi in the area - according to THEM.

There you go again, its like you are trying to put us in an out group or something... In groups and out groups are nothing more than a feeble attempt at manipulating others, and in the end almost always end up burning those who see the world that way the most. You should be careful with this, it is a good way to burn yourself.

And I don't recall ever using the term idiots.

You called me an idiot in a discussion of the Maco and Imax antennas when I not only used actual experience that differed from yours, I also told people that they should do their own research on the topic rather than use the, at the time, rather heated discussion between us.

My use of the term "Gods" was with reference to the book writers, not you Sir. :)

Fair enough.

...just burned out on being told that what performed in an OUTSTANDING manner in the real world, wasn't poop according to theory.

Strange, no one actually said or implied anything of the sort, and as a matter of fact, on more than one occasion in this thread above I stated that I preferred the quad over the yagi designs for any number of reasons, that is hardly calling the quad "poop".

Believe it or not, you aren't the only person here who has direct experience with these antennas, and with all due respect, I highly doubt you have as much as I do, yet all you think I put forth is theory? When it comes to the two of us you are not the only person who has built quad antennas either, as I mentioned one I built a long time ago as well. The biggest difference between us is you do something once or twice and then act like you are the end all and be all of knowledge on the subject, not even listening to reason from others who did the exact same thing. When I do something once or twice, I then look for the potential flaws in what was done and seek to do it again, only better. For me, an understanding of theory is the path to doing it better. In this regard we are clearly very different.

I'd rather help someone build one than repeatedly argue why it will or won't work.

Its not you helping others that we are arguing against, and if you think that it is then you simply aren't paying attention.

NB
Back in the early 80's armed with only a vswr meter & signal meter how did you measure "resonance" to determine that only impedance at the feedpoint changed as you added the parasitic elements ?

This is a very good question as with my VNA a car passing 30 or so feet away from a mobile antenna I am tuning is enough to affect reactance, and puts little bumps on the readout, and birds flying by are enough to put little spikes on the readout, both of these can add over +5 ohms of reactance, and this change is always positive, which means the change in reactance is capacitive. I've mentioned this effect several times in the past on this and other forums. These things are affecting the antenna enough to be picked up with a VNA, yet parasitic elements don't affect the antenna in this way at all?


The DB
 
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Of course they move resonance DB,
i was interested in hearing how NB determined it does not move, see if we can find the error in his methology.
Yeah, and that's why I'm finished being frustrated having to endlessly defend a fabulous antenna, over and over.

I offered the measurements & formulas to the best of my memory, cited the best & most specifics I can - but obviously you guys aren't interested in the info I've shared for what it is,
- you just want to, "find the error".

I'm bored & tired of it.

Obviously it wouldn't have been such a Yagi-killer if it wasn't resonant or, or, or & on & on & on...
I'm now truly sorry I ever mentioned it. I'm done.

Enjoy using your Yagi



...theory.
 
Hold on NB, let me find my violin & some tissues.

you are making incorrect claims about killer quads & arguing instead of listening,

back in your monster quad building days you had no idea what resonance was let alone able measure it with a vswr meter & determine resonance does not move,

I understand why your done & wish you never mentioned it,
 
Yeah, and that's why I'm finished being frustrated having to endlessly defend a fabulous antenna, over and over.

I, for one, never said anything that would require you to defend your antenna, I never said nor implied that it was a bad antenna, and for the record, I think this is the fifth time (or so) I'm stating in this thread alone, that I prefer quads over yagis. You say it is a great antenna, and I have no reason not to believe that, as long as you like it I am happy for you.

But...

How well your antenna works is completely irrelevant to what I, and at least most others, were actually saying.

Apparently you can't separate your coveted antenna from this discussion and because of that refuse to acknowledge the facts about yagi's and quads. That is unfortunate.

When it comes to your antenna, if you said `I have a quad and it works great', and then recommended it no one would have said anything about it. Instead you made claims about quads in general that are not completely true when compared to a yagi that was made with the same type of tuning in mind. I'm sorry, but that is reality, no matter how much you want to believe. And those author gods you mentioned above? Perhaps you should actually read what they say about this, you will be surprised.

One thing that you haven't factored in is very few yagi's, especially on the CB band, are tuned for maximum forward gain, unlike quads. If you want to make a fair comparison then you need to make a yagi that is designed to have the maximum amount of forward gain for its size. Unless you know the layout for said yagi you would first need to do some research to figure out which one to use.

Forward gain isn't all their is to beam antennas either, so harping on this one point really doesn't do anything for your argument. In my opinion, forward gain comes in at best as second to where and how deep the nulls of the antenna are.


The DB
 
I, for one, never said anything that would require you to defend your antenna, I never said nor implied that it was a bad antenna, and for the record, I think this is the fifth time (or so) I'm stating in this thread alone, that I prefer quads over yagis. You say it is a great antenna, and I have no reason not to believe that, as long as you like it I am happy for you.

But...

How well your antenna works is completely irrelevant to what I, and at least most others, were actually saying.

Apparently you can't separate your coveted antenna from this discussion and because of that refuse to acknowledge the facts about yagi's and quads. That is unfortunate.

When it comes to your antenna, if you said `I have a quad and it works great', and then recommended it no one would have said anything about it. Instead you made claims about quads in general that are not completely true when compared to a yagi that was made with the same type of tuning in mind. I'm sorry, but that is reality, no matter how much you want to believe. And those author gods you mentioned above? Perhaps you should actually read what they say about this, you will be surprised.

One thing that you haven't factored in is very few yagi's, especially on the CB band, are tuned for maximum forward gain, unlike quads. If you want to make a fair comparison then you need to make a yagi that is designed to have the maximum amount of forward gain for its size. Unless you know the layout for said yagi you would first need to do some research to figure out which one to use.

Forward gain isn't all their is to beam antennas either, so harping on this one point really doesn't do anything for your argument. In my opinion, forward gain comes in at best as second to where and how deep the nulls of the antenna are.


The DB

Hold on NB, let me find my violin & some tissues.

you are making incorrect claims about killer quads & arguing instead of listening,

back in your monster quad building days you had no idea what resonance was let alone able measure it with a vswr meter & determine resonance does not move,

I understand why your done & wish you never mentioned it,
Here Bob, you can borrow mine...
violin.gif
(the GF loves that one)

Anyway, Quads rule and that's just the way it is.

Now, go get or build one and enjoy the upper echelon of performance, or stay with the inferior yagi design and get squished, up to you, but when that Quad pummels your signal into the dirt you can always go running back to your theory books for comfort, or give Tom a call and laugh about how it just can't be...

Happy Yagis! (y)
 
Now, go get or build one and enjoy the upper echelon of performance,

As I stated above, been their done that. As I also stated above, you are not the only person around here who has worked directly with these antennas. Assuming everything that you disagree with is based on theory alone is flat out incorrect and a huge leap of faith.

I'm glad your quad is working for you, but the reality is that doesn't make every quad automagically better than every yagi. That is all I am saying, and I don't need to rely on theory to know that.


The DB
 
Hey NB, I have continued to work with my model of the 5 element Quad using your information as best I understand it. I have not matched the antenna as yet. Do you recall or know even close to the length of your matching line you used...or did you use a gamma match? It sure might save me a lot of trial an error if you would give up that little secret.

My model to this point has been tuned for a good match and not maximum gain. I think that limits the optimizing possibilities somewhat using the spacing and loop size to get more gain.

I have been working with this 5 element and I have seen some really good gain figures but the match was really bad and I was thinking it might be possible to get some more gain and then tune it with a 75 ohm line to show a good match at resonance without destroying the match.

I already have a whopping good rejection model with over -40db front to back. I know you could tell that using only your radio...but I'm not to sure one could really tell the difference in gain I've been seeing...and it isn't much difference using a balance spacing scheme thus far.

Below is the Free Space pattern with the max front/back noted in the antenna details printed out here.
 

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