quad reflector versus yagi reflector

[Needle Bender]

I realize you guys don't consider my modeling of any value, but don't think the tools are worthless in the hands of well qualified folks in this world.

I wouldn't advise you subscribe to a mutual exclusivity syndrome, Ed, you know we, all of us, appreciate your effort, all of it, modeling, posting, testing, etc. - I just have to disagree with any model which appears to contradict or demean a real-world success, and that's not you or necessarily the modeling program's fault, more likely the lack of complete parameters in consideration by the modeling program, some of which may be random and found only in rare instances of installation &/or application.
Don't you dare throw in the towel on what you do so well, it's definitely very helpful & widely appreciated!

 

[Captain Kilowatt]

I realize you guys don't consider my modeling of any value, but don't think the tools are worthless in the hands of well qualified folks in this world.

Please do not think that you speak for me. I do not think it has no value. I do however think that modeling gets CLOSE. Real world on-site tweaking is what makes the final result. No different than anything else that uses a number of data points to compute the outcome of something. There is always a certain percentage of error.

 

[Marconi]

I wouldn't advise you subscribe to a mutual exclusivity syndrome,

NB, just in case you are surprised...I won't be taking any advice from you, you have always failed me when the rubber hit the road.

You gave us a process for tuning your Quad and Bob questioned the process, but you never responded his words just like you do most of the time.

I regret I didn't just leave this thread alone. The thread would likely have ended and no body gaining any insight to consider by further discussions and this often happens when someone ask a pertinent question.

I thought it interesting though...we had two ideas with apposing positions on your process for tuning your Quad. You should be talking to Bob, trying to explain his doubts.

My personal experience with a Quad did not exactly agree with the results you claimed...that by cutting you could get the antenna to go to it lowest point below 2.00:1 SWR. It didn't even happen when I added wire to the antenna. I'm not picking on you like The DB might exclaim, I just had a totally different experience in trying to tune my single Quad element.

Since you're getting Freudian on me, I'll give you...that you could have meant adjustment of the wire length instead of cutting. In my experience I had to add wire to get the SWR to go down and it never went below the red on my SWR meter. That is what my model shows today, the wire was too short and cutting was going the wrong way in adjusting.

Do you think this fact could change if I model at the same frequency in every possible condition that this Earth might present? NO, not even on my best day!

So, I made a single Quad model trying to explain if your process was possible with a single Quad element. Without going into the details, I even tried to explain how your hands on experience might be possible...using a feed line to measure your results. I can only assume that my model and/or my words...when right over your head.

I can understand folks that have no modeling experience missing the point sometime. Modeling cannot duplicate all the variables in this world all at once. That is why you guys need to be considering what Free Space models show...but the bias against FS modeling is even more misunderstood than over Real Earth.

Do you know the technical difference between a Free Space model and one over Real Earth...other than the pictures for the patterns are different?

If you don't respond, it is probably for the same reasons you did not respond to Bob's perfectly reasonable objects to your process in tuning a multi-element antenna. I will make note of the fact that you did correct the misconception you left...when you posted the formulas again at the bottom of your post #75, without all the details where you alluded to the idea...claiming you tuned all the elements independally.

Thanks for the kind words though.

 

[Marconi]

Please do not think that you speak for me. I do not think it has no value. I do however think that modeling gets CLOSE. Real world on-site tweaking is what makes the final result. No different than anything else that uses a number of data points to compute the outcome of something. There is always a certain percentage of error.

Please don't think I include you in a group of folks.

If I did take a notion to speak for you...I would reference your name.

That said, I remember your stance on modeling...as noted in your post #86 in this thread.

quad reflector versus yagi reflector

 

[wavrider]

I do not model, but I do a lot of research and review many different models of the same type antenna by different sources.

IF I discover a EZNEC model that is different than others of the same type antenna it perks my interest as to "Why is this different than others".

I like building antennas, experimenting, etc.

I have found Marconi's " Eddie's" models be very useful especially when he does several models and over lays them.

I can not tell you if Ed's modeling is correct or incorrect I can tell you I have built antennas based on Ed's models and they were effective ( hard to measure efficiency with a receive meter).

I have not taken the time to learn EZNEC, between my family and work I barely have time to even enjoy the hobby of radio but when and if I get time I enjoy it tremendously.

Ed keep posting those models, keep learning and improving cause I am positive I am not the only amateur antenna builder that is benefiting from your time and efforts.

 

[Marconi]

Wavrider, thanks you for the kind words.

 

[IRock817]

I started reading the first few pages here and then jumped to the last few!
Not a tech here by no means!
Throwing out there that I run a, what I call a PDL4 here, or at least will again after ice damage repair, and its great! Especially for in or around the city!
The guy that designed it spent countless days in these and it shows!
Like I said, I'm just an operator and have been since '83 for the most part and have ran several antennas!
Wouldn't trade a quad for no other! Except for a P500 on the temporary!

Not on topic I'm sure! Just my two cents!

 

[Needle Bender]

NB, just in case you are surprised...I won't be taking any advice from you, you have always failed me when the rubber hit the road.

You gave us a process for tuning your Quad and Bob questioned the process, but you never responded his words just like you do most of the time.

I regret I didn't just leave this thread alone. The thread would likely have ended and no body gaining any insight to consider by further discussions and this often happens when someone ask a pertinent question.

I thought it interesting though...we had two ideas with apposing positions on your process for tuning your Quad. You should be talking to Bob, trying to explain his doubts.

My personal experience with a Quad did not exactly agree with the results you claimed...that by cutting you could get the antenna to go to it lowest point below 2.00:1 SWR. It didn't even happen when I added wire to the antenna. I'm not picking on you like The DB might exclaim, I just had a totally different experience in trying to tune my single Quad element.

Since you're getting Freudian on me, I'll give you...that you could have meant adjustment of the wire length instead of cutting. In my experience I had to add wire to get the SWR to go down and it never went below the red on my SWR meter. That is what my model shows today, the wire was too short and cutting was going the wrong way in adjusting.

Do you think this fact could change if I model at the same frequency in every possible condition that this Earth might present? NO, not even on my best day!

So, I made a single Quad model trying to explain if your process was possible with a single Quad element. Without going into the details, I even tried to explain how your hands on experience might be possible...using a feed line to measure your results. I can only assume that my model and/or my words...when right over your head.

I can understand folks that have no modeling experience missing the point sometime. Modeling cannot duplicate all the variables in this world all at once. That is why you guys need to be considering what Free Space models show...but the bias against FS modeling is even more misunderstood than over Real Earth.

Do you know the technical difference between a Free Space model and one over Real Earth...other than the pictures for the patterns are different?

If you don't respond, it is probably for the same reasons you did not respond to Bob's perfectly reasonable objects to your process in tuning a multi-element antenna. I will make note of the fact that you did correct the misconception you left...when you posted the formulas again at the bottom of your post #75, without all the details where you alluded to the idea...claiming you tuned all the elements independally.

Thanks for the kind words though.

OK, so I guess it's ME in your cross-hairs THIS week, lol.

- It was Henry a few weeks ago, The DB after that, now I'm the bad guy. Hmmm.

It's really not an arguable point. I built it, told you how, it kicked royal arse and that's that.

Anyway, I answered the best I can & care to, and now that you mentioned Freudian, I think I'll go have a cigar.

 

[Marconi]

OK, so I guess it's ME in your cross-hairs THIS week, lol.

- It was Henry a few weeks ago, The DB after that, now I'm the bad guy. Hmmm.

It's really not an arguable point. I built it, told you how, it kicked royal arse and that's that.

Anyway, I answered the best I can & care to, and now that you mentioned Freudian, I think I'll go have a cigar.

NB, I at least tried a model from the start of your tuning idea and adding one element at a time to try and see if your tuning procedure could be verified using modeling, and that showed Bob is right.

BTW NB, what did you use as spacing on your Quad?...you failed to post that very important information. Is this a fair question?

I can't say your personal experience was wrong or that you didn't get the results you reported...I wasn't there. My argument to you is that Bob made a reasonable point and posed a good question. I made the model to try an prove his point as well. I think it could be said both of your ideas were at odds and that got me curious.

Along with my personal experience with a single driven element Quad that I posted, recounting my having no success at getting it to tune below 2.00:1 SWR, as you reported you did, and the results from the two original models I posted earlier, and after tuning to resonance and adding one element at a time similar to the process you posted, the models don't support what you reported either, not even close.

I did try and explain how it might be possible that you could show better results if you were taking your readings during tuning using a moderately long feed line or jumper.

As a note: my models show the match directly at the feed point...the only place we can ever be sure...what the antenna match really is.

So NB, I think I treated this demonstration fairly with you. I would have surely posted what I found had the results come out the other way. And then, I guess you would say I have Bob in my cross-hairs. I only speak out to you guys if and when I think you might be wrong or I have a question. What's wrong with that?

I think the simple problem is you guys, and you should know who that is, don't like your words questioned, and you sure don't like having to explain.

Personally, I think my models can get very similar or real close to what might actually happen in a simple CB antenna like we are discussing. However, when I think there is something I've missed or something is wrong with my model or any other, I will start asking questions. I'm here to learn thru discussion and try and understand the ideas of others...not take pot-shots at my buddies on this forum.

On the other hand, if anybody has some real evidence to the contrary (not just words)...then speak up and post what you have.

Enjoy that cigar!

 

[Captain Kilowatt]

One advantage of a quad over a yagi is that element spacing is not as critical as to gain. The quad is a bit more forgiving in that regard and altering the element spacing to achieve impedance matching is not as detrimental to gain as in a yagi.

 

[Needle Bender]

NB, I at least tried a model from the start of your tuning idea and adding one element at a time to try and see if your tuning procedure could be verified using modeling, and that showed Bob is right.

BTW NB, what did you use as spacing on your Quad?...you failed to post that very important information. Is this a fair question?

I can't say your personal experience was wrong or that you didn't get the results you reported...I wasn't there. My argument to you is that Bob made a reasonable point and posed a good question. I made the model to try an prove his point as well. I think it could be said both of your ideas were at odds and that got me curious.

Along with my personal experience with a single driven element Quad that I posted, recounting my having no success at getting it to tune below 2.00:1 SWR, as you reported you did, and the results from the two original models I posted earlier, and after tuning to resonance and adding one element at a time similar to the process you posted, the models don't support what you reported either, not even close.

I did try and explain how it might be possible that you could show better results if you were taking your readings during tuning using a moderately long feed line or jumper.

As a note: my models show the match directly at the feed point...the only place we can ever be sure...what the antenna match really is.

So NB, I think I treated this demonstration fairly with you. I would have surely posted what I found had the results come out the other way. And then, I guess you would say I have Bob in my cross-hairs. I only speak out to you guys if and when I think you might be wrong or I have a question. What's wrong with that?

I think the simple problem is you guys, and you should know who that is, don't like your words questioned, and you sure don't like having to explain.

Personally, I think my models can get very similar or real close to what might actually happen in a simple CB antenna like we are discussing. However, when I think there is something I've missed or something is wrong with my model or any other, I will start asking questions. I'm here to learn thru discussion and try and understand the ideas of others...not take pot-shots at my buddies on this forum.

On the other hand, if anybody has some real evidence to the contrary (not just words)...then speak up and post what you have.

Enjoy that cigar!

Well, remembering the 80s, hmmm... OK, spacing, from the reflector moving forward

.18 Ref to Driven, .15 Driven to Dir 1, .175 1 to 2, .225 2 to 3. about 27' of boom.

SWR was mitigated by using a matching system.

One type I recall which Signal Engineering used and which I helped a friend tune required the coax to have no connector but be split at the end exposing about 3" of both shield & center conductor to be attached to a set of parallel brass rods (which were also in parallel to the boom) and slid along those rods to find the correct impedance point.

I somehow missed Bob85's post asking about mutual coupling, I might be mistaken but had thought it referred to the impedance change when parasitic elements are added, not any change in Driven wire resonance length.
Of course a matching network was employed to zero the reactance & locate a satisfactory impedance point, making any change from the initial driven element 2:1 swr, by adding parasitic elements, a moot point.

 

[bob85]

NB when you bring a parasitic element near to the driven element mutual coupling changes the resonance & impedance of both elements,

i have never made an antenna model in my life, but i have made quads in the early 80's from wire & wood using a cb vswr meter & s-meter & lots of trial and error,

They worked as well or a little better than my tagra & lemm yagis on a 20ft pole,
not that its anything to brag about,
when i took the lemm down i found the instructions tucked inside the boom,
i had the director & reflector at the wrong end but it still worked.

 

[Needle Bender]

NB when you bring a parasitic element near to the driven element mutual coupling changes the resonance & impedance of both elements,

i have never made an antenna model in my life, but i have made quads in the early 80's from wire & wood using a cb vswr meter & s-meter & lots of trial and error,

They worked as well or a little better than my tagra & lemm yagis on a 20ft pole,
not that its anything to brag about,
when i took the lemm down i found the instructions tucked inside the boom,
i had the director & reflector at the wrong end but it still worked.

Bob, I disagree. The resonance of the antenna system is certainly affected by the addition of parasitic elements, as is the impedance, (both dropping the original 2:1 of the solo driven element SWR much closer to 1:1 when added) but the VF of the wire in use shouldn't change, leaving the resonant length of the driven element loop wire intact - any system impedance mismatch tuned out with the matching feedline.

And if you're implying your homebrew quad's performance was poor, you must've built &/or tuned it a bit poorly.

 

[wavrider]

 

[The DB]

but the VF of the wire in use shouldn't change

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