[NLRS] Yagi Design (Was: Club Cheap Yagi Build Day Advice Needed)

[Dr. Gerald N. Johnson]

On 11/27/2016 5:34 PM, James Duffey wrote:
> OK Jerry - Thanks for the reply. Glad to see we are now in agreement.
> I think that MMana-GAL kind of defaults to putting the source in
> element one; at least it was hard for me to find a way to do it
> otherwise and to get a file to run.

Most of the time Mmana-Gal expects to set the segmentation so assigning 
a load or source by segment won't work. I don't remember using W2C but I 
think it will work.
>
> As a rover, I am very interested in the stacking heights for antennas
> and pretty much stack things close. It is hard to keep them at good
> spacing, though, but it all seems to work OK. I try to avoid having
> antennas with odd harmonic relationships next to each other as there
> are considerably more currents induced in the odd harmonic
> relationships than in the even ones. So, starting at 13 ft, my stack
> looks like: 6M Moxon, 222MHz Yagi, 144MHz Yagi, 902MHz Yagi, 432 MHz
> Yagi, 1296MHz Yagi. The spacing between 432MHz and 1206 MHz is less
> than I would like, but it is possible to get better separation
> isolation wise between 432 and 1296 than it is between 144 and 432.
> And 432MHz is kind of a crippled band in NM anyway as we are limited
> to 50W RMS transmitter output power. No, antenna gain is not
> considered. Yes, that is ridiculous. Of all the considerations, I
> think that having the 6M antenna as the top one on the stack is
> critical. I think it is also important to keep each antenna more than
> 1/2 wavelength above any car metal, and that stacking achieves that.

6m meets more height above the effective ground plane for low angle 
radiation, so in a short stack it ought to sure be on top.

The last graph in my paper shows how the effect on gain correlates with 
boom spacing in wavelengths on the high band. Less than 1/2 dB at 1 
wavelength boom spacing, around 1 dB gain reduction at 1/2 wave, more at 
closer spacing. And roughly my measurements out in the yard agreed with 
the modeling after drift correction. The graph before that shows a very 
poor correlation of gain loss vs spacing in boom lengths. The two are 
the point of the paper.
>
> CSVHF is in Albuquerque next year and I know at least one local ham
> who has a spare 2M9SSB that I will try to talk him into bringing to
> the testing. It is a big antenna for that kind of test range though.

There have been longer yagis measured, sometimes the results have been 
scoffed at by the observers.
>
> I hope you can get to Albuquerque for CSVHF next year. It should be a
> good time. - Duffey

That is a longer distance than I've gone to CSVHF since the 70s when I 
did get to Boulder once.

One of my unachieved travel plans is to ride all the tourist railroads 
in Colorado that could be a week or more pre CSVHF trip. And visit 
various museums, mostly aircraft, railroad, and transportation museums. 
I'm not aware of any technological museums but they might be there. It 
would be an easier trip if I had wheels under my vintage Airstream that 
has been to many CSVHF gatherings. Having been around dopeheads while in 
the Army I'm not exactly enthusiastic about recreational pot smoking in 
Colorado. Dopeheads have no concern about safety, either their own or 
anybody elsees.

Such a journey through Colorado may need lots of detailed planning, the 
pickup and Airstream have been getting 15 mph at 52 (indicated) mph and 
lots of commercial campgrounds are booked long ahead and are pricey. I 
can get discounts at Wyndham hotels through Farm Bureau but that means 
really tying down plans with reservations ahead of time, but the Fieste 
ecoboost runs around 40 mpg at 75 mph. If I get the new axle mounted I 
expect it will allow faster highway speeds at a cost in fuel.

Then I'd like to get home in time for the August UHF contest but I could 
try roving though between NM and here I think contacts would be hard to 
make. They are hard here near the Boondocks compared to the twin cities 
and Chicago. I did bring home a 2.3 GHz transverter from MUD this year. 
Haven't applied power yet.

73, Jerry, K0CQ
>
>
> On Nov 27, 2016, at 2:21 PM, Dr. Gerald N.
> Johnson<geraldj at netins.net>  wrote:
>
>>
>>
>> On 11/27/2016 2:27 PM, James Duffey wrote:
>>> OK Jerry - I finally got some time to spend with MMana-GAL and
>>> loaded up your M2 2M9SSB *.maa file. I am used to the elements
>>> running left to right from 1 to 9 as the convention for
>>> specifying elements, so that is what threw me at first. But you
>>> were correct, the source is in the correct element in your file.
>>
>> I often put the driven element as wire 1 so the segment for the
>> feed is more constant. My model data did show segment 25 as the
>> point, but I changed it to W1C.
>>>
>>> I ran it and I got the same results you did. So we are on the
>>> same page as to modeling with MMana-GAL. I then began to
>>> investigate why your model gives results that are different from
>>> other modeling of the same antenna as well as the M2
>>> specifications and what one would expect from a well designed
>>> antenna of that length. It looks to me like the element radius
>>> you specified, 0.8 mm or 1/32 inch, is too small to accurately
>>> represent the actual element diameter, which is specified as
>>> 3/16” by M2. So, I increased the element radius to 2.38mm, or
>>> 3/32”, which is half the 3/16” actual element diameter as
>>> specified by M2.
>>
>> 0.8mm as displayed on the geometry page is the default, think 14
>> gauge wire for an HF antenna. I entered .09375*i and it displayed
>> 0.002381 mm by doing the math as for meter as the unit which is
>> what it displayed in your file.
>>
>> The smaller diameter increased resistive losses a bit and the
>> resonant frequency a couple MHz moving the peak gain up to about
>> 149 instead of 145 and that's where most of the gain difference
>> went.
>>
>> I don't remember that a M2 2mSSB9 has been measured at CSVHF but I
>> will have to take a hard look one of these days.
>>>
>>> I ran that model and that increased the gain to 11.89dBD, which
>>> is about 1.1 dB higher than what your original file calculated
>>> and close to the M2 gain specification of 14.1dBi (11.96dBD) as
>>> well as close to the VE7BQH calculated value of 12.01dBD. The
>>> change in element diameter of three times is pretty significant
>>> in moving the gain peak around at those frequencies without any
>>> corresponding adjustments to element length. I ran the same
>>> dimensions in your file with the corrected radius with YagiCad
>>> and modeled a 12 dBD gain, which is also in line with what M2 and
>>> VE7BQH list as actual gain. I am not sure if there are additional
>>> tweaks or corrections to be found in your file or not, but I
>>> suspect that the differences between the calculated gain values
>>> with the correct element radius are not significant and  may be
>>> due to the differences in the MININEC and NEC2 computing engines.
>>> I am not sure why this should be though, as the problems that
>>> MININEC solve better than the NEC2 engine, the closely spaced
>>> elements, are not really present in this antenna. Still, 0.07dB
>>> difference is probably not really enough to worry about. I did
>>> verify that the boom correction had been subtracted out properly.
>>> The model I ran in YagiCad was in free space without the boom,
>>> just as your file models. That is a good way tot model the
>>> antenna.
>>
>> I want to see the face of any antenna range operator who claimes to
>> measure gain to .05 dB repeatability. I don't believe that is
>> practical. Easy enough to compute with a VNA but move the antenna
>> one degree or one inch and it will change that much from odd not
>> fully suppressed range reflections.
>>>
>>> The exercise did satisfy my curiosity as to why you got similar
>>> gain results in modeling the 10 ft K1FO and the M2 2M9SSB at 14.5
>>> ft in your paper on stacking - the M2SSB antenna is modeled with
>>> the wrong element diameter.
>>
>> I still like the 10 ft K1FO and plan to put up a pair of them for
>> 2m and 3 for 432 some eon. The 432 versioin that i took to CSVHF
>> twice measured more gain than computed. Stacking will improve the
>> gain without adding to the azimuth directivity and so make for
>> easier pointing. I have a FO-22 on 432 on the roof tripod and
>> aiming it is a real pain, especially when the rotor direction
>> indicator isn't working. So I aim by knowing what direction it
>> starts out at and then watching the sweep second hand on a wall
>> clock, then I go out on the back deck and check for what I see and
>> often correct. I need a lot more height too.
>>
>> The point of the paper still is fine, that one doesn't need to
>> stack 432 and 2m beams half a boom length apart that there isn't a
>> gain loss until the booms are a wavelength apart which is much
>> closer than the half a boom length intended to keep the capture
>> areas from overlapping. The close spacing is often used by rovers
>> quite successfully even before this paper. Half a boom spacing is
>> about right for maximum stacking gain of identical yagis for the
>> same band.
>>
>> I was surprised that the effects on the high band pattern from
>> currents in the low band elements was more in the elevation pattern
>> than the azimuth pattern. I expected to see +/- 45 degree azimuth
>> lobes typical of a 3/2 wave dipole.
>>
>> Well now we have a topic for another CSVHF paper, correcting my
>> 2011 paper on the M2 modeling. No one else has noticed it. Can be a
>> short paper, won't have to redo the stacking parts.
>>
>> 73, Jerry, K0CQ
>>>
>>> Here is the *.mma file I used for the MMana-GAL calculations:
>>>
>>> 2m9ssb * 144.2 ***Wires*** 9 0.25083,               -0.49428,
>>> 0.0,         0.25083,               0.49428,               0.0,
>>> 0.00238,               50 0.0127,  -0.51412,              0.0,
>>> 0.0127,  0.51412,               0.0,         0.00238, 50 0.57626,
>>> -0.46443,              0.0, 0.57626,               0.46443,
>>> 0.0,         0.00238, 50 0.87313,               -0.46163,
>>> 0.0, 0.87313,               0.46163,               0.0,
>>> 0.00238, 50 1.41764,               -0.46333,              0.0,
>>> 1.41764,               0.46333,               0.0,
>>> 0.00238, 50 2.12407,               -0.45698,              0.0,
>>> 2.12407,               0.45698,               0.0,
>>> 0.00238, 50 2.90195,               -0.45063,              0.0,
>>> 2.90195,               0.45063,               0.0,
>>> 0.00238, 50 3.76238,               -0.44762,              0.0,
>>> 3.76375,               0.44762,               0.0,
>>> 0.00238, 50 4.4323,  -0.4508,                0.0,         4.4323,
>>> 0.4508, 0.0,         0.00238,               50 ***Source*** 1,
>>> 0 w1c,       0.0,         1.0 ***Load*** 0,            1
>>> ***Segmentation*** 800,        80,          2.0,         2
>>> ***G/H/M/R/AzEl/X*** 0,            0.0,         3,
>>> 21.0, 120,        60,          0.0 ###Comment### Element radius
>>> increased from 0.8mm to 2.38mm to reflect actual antenna Source
>>> changed from 25 to w1c as MMana-GAL would not take segment 25 Mod
>>> by James R. Duffey KK6MC 11/27/2016 1039 Mod by Gerald N.
>>> Johnson, K0CQ 1/23/2011 6:19:23 PM Created by Gerald N. Johnson,
>>> K0CQ 1/23/2011 5:08:08 PM
>>>
>>> In addition to the radius change, I also had to change the
>>> location designation of the source in your file from 25 to W1C.
>>> My version of MMana-GAL did not recognize 25 as a valid location
>>> for the source and wouldn’t run the file. I had to read the
>>> MMana-GAL help file to figure that one out. It has been a long
>>> time since I ran MMana-GAL, so I am not sure if the way to
>>> designate the source has changed or not. I think that the rest of
>>> the file is identical to yours. Run it and see what you get.  -
>>> Duffey KK6MC
>>>
>>>
>>>
>>> On Nov 21, 2016, at 3:58 PM, Dr. Gerald N.
>>> Johnson<geraldj at netins.net>   wrote:
>>>
>>>> Load the file and do a view. Element 1 is the driven element,
>>>> element 2 is the reflector. Its not wrong.
>>>>
>>>> 73, Jerry, K0CQ
>>>>
>>>> On 11/21/2016 2:57 PM, James Duffey wrote:
>>>>> Jerry  - I haven’t had time to run your M2 2M9SSB MMana-GAL
>>>>> file yet as I was busy with Sweepstakes all weekend. After a
>>>>> quick glance at your *.maa file though, I think I see the
>>>>> reason why your modeled gain is lower than what M2, VE7BQH,
>>>>> and myself calculate. It looks to me like you placed the
>>>>> source in element one, the reflector, rather than in element
>>>>> 2, the driven element. Try moving it to the driven element
>>>>> and let us know how it models. Should be quick and easy to
>>>>> do. I will also do that when I get a chance.
>>>>>
>>>>> I knew Warren well and we carried on a long discussion on
>>>>> source conjugate matching, both through snail mail, and at
>>>>> the Iowa/Midwest Division conventions. I was saddened when I
>>>>> got the letter with his obituary and a note from his family.
>>>>> We lost a great technical ham when he died. Warren taught me
>>>>> the “one degree rule”, which he said was passed down to him
>>>>> by Art Collins himself.  - Duffey KK6MC
>>>>>
>>>>>
>>>>>
>>>>>
>>>>> On Nov 19, 2016, at 3:20 PM, Dr. Gerald N.
>>>>> Johnson<geraldj at netins.net>    wrote:
>>>>>
>>>>>>
>>>>>>
>>>>>> On 11/19/2016 10:24 AM, James Duffey wrote:
>>>>>>> Jerry - We have strayed fairly far from the original
>>>>>>> topic, so I have changed the subject accordingly. That
>>>>>>> way people who are only interested in the WA5VJB antenna
>>>>>>> build can skip over it if not interested.
>>>>>>>
>>>>>>> I use MMana-Gal as well as YagiCad and 4NEC2 in my
>>>>>>> modeling of the WA5VJB antenna. For serious work, not
>>>>>>> that Bill’s WA5VJB project isn’t serious, I use a couple
>>>>>>> of different tools to confirm modeled results, generating
>>>>>>> new input files as I go. Testing without a good antenna
>>>>>>> range makes it difficult to confirm results, but if the
>>>>>>> SWR or directivity is way off that is usually a clue that
>>>>>>> there is a problem in the design or modeling, and if one
>>>>>>> can wait a year for the CSVHF conference to roll around,
>>>>>>> the antenna range there is useful. A number of years ago
>>>>>>> when I had access to a licensed version of CST, a
>>>>>>> professional (read expensive) 3D electromagnetic
>>>>>>> simulator and NEC4 (controlled access only), I modeled
>>>>>>> the 3 element WA5VJB in those as well. Interestingly
>>>>>>> enough, the electrical properties of the antenna varied
>>>>>>> little with which model one used. I was aware of the
>>>>>>> closely spaced wires issue from W7EL’s work as well as
>>>>>>> conversations with Cebik at Dayton while he was still
>>>>>>> alive, so this good agreement was a bit of a surprise to
>>>>>>> me. However, when I modeled a dipole, a folded dipole,
>>>>>>> and Kent’s J shaped driven element (It is really more
>>>>>>> accurately described as a half a folded dipole) with the
>>>>>>> different models, they all showed the same gain and
>>>>>>> pattern. Only the input impedance and VSWR bandwidth were
>>>>>>> different, as one would expect. This makes sense as a
>>>>>>> dipole is a dipole, regardless of the physical form it
>>>>>>> takes. That gave me confidence that the WA5VJB antenna
>>>>>>> could be modeled well with any of those tools. This all
>>>>>>> makes sense in the context of how the Yagi works; the
>>>>>>> driven element serves to launch the electromagnetic wave
>>>>>>> in the antenna, and as long as the driven element
>>>>>>> geometry is efficient and balanced, then the particulars
>>>>>>> of the driven element are really only important as to
>>>>>>> matching to the feed line. With this in mind, the WA5VJB
>>>>>>> antennas can be modeled with simple dipoles or folded
>>>>>>> dipoles as the driven elements as far as things like
>>>>>>> element diameter correction, boom correction, and
>>>>>>> frequency scaling go. One just needs to account for the
>>>>>>> driven element impedance when looking at things like VSWR
>>>>>>> and matching or model the VJB driven element exact.
>>>>>>
>>>>>> I model a yagi like the M2 or K1FO by taking the elements
>>>>>> and running the G3SEK basic dos program (element.bas) to
>>>>>> remove the boom correction and I model without a boom. I
>>>>>> haven't found a method of moments program that handles
>>>>>> intersections of different diameter wires or intersections
>>>>>> not at 90.0000 degrees well. The fundamentals are that the
>>>>>> currents are presumed to be at zero diameter at the center
>>>>>> of the wire and that the coupling is from the center of the
>>>>>> segments nearest the intersection. When at 90 degrees the
>>>>>> coupling is figured as zero because the fields are at right
>>>>>> angles. Unfortunately the current distribution is not
>>>>>> anywhere near like that presumption. Especially in close
>>>>>> spaced conductors.
>>>>>>
>>>>>> I invented an antenna I called a Cat's Cradle involving
>>>>>> angled 1.5 wave radiators gathered like a gang of small
>>>>>> rhombics. Modeling in EZNEC the gain and patterns varied
>>>>>> drastically with slight changes of inputs, as much as over
>>>>>> 3 dB change in gain for a tiny change. I whipped one
>>>>>> together a day before CSVHF and took it and it displayed
>>>>>> the gain of the lowest modeling results, not the peak. It
>>>>>> also as a single array worked better with the boom vertical
>>>>>> than pointed at the 1296 signal source, much like a diamond
>>>>>> array. In my modeling stacking 4 cleaned up the strong
>>>>>> elevation lobes. But I only built one.
>>>>>>
>>>>>> That experience and many claims for great front to side
>>>>>> ratios enhanced by flat loop driven elements or angled
>>>>>> driven elements that were guaranteed to couple current to
>>>>>> the boom caused me to publish
>>>>>> http://www.geraldj.networkiowa.com/papers/2013/FinePoints.pdf
>>>>>>
>>>>>>
in both CSVHF and MUD 2013.
>>>>>>>
>>>>>>> I have never heard the pejorative Crumcraft used when
>>>>>>> referring to CushCraft before. I have heard of them
>>>>>>> referred to as CushCrap though. They were more crippled
>>>>>>> by their marketing department than the performance of
>>>>>>> their antennas, although now that MFJ owns them, that may
>>>>>>> have changed. The CushCraft antennas based on NBS Tech
>>>>>>> Notes 688 perform as one would expect from the NBS data,
>>>>>>> which is not too surprising as those antennas were
>>>>>>> designed to be reproducible if one followed the
>>>>>>> directions in the Tech Note for designing and building
>>>>>>> the antennas.
>>>>>>
>>>>>> That is my invention. Their NBS copies did work as the
>>>>>> originals but they claimed several more dB claim, like
>>>>>> adding ground reflection gain or link gain with the same
>>>>>> antennas on both ends of a link. Maybe their reference was
>>>>>> a rubber duck antenna inside a fruit juice can. Their
>>>>>> outrageous gain claims caused a permanent QST policy that
>>>>>> antenna gain claims are not allowed in QST advertisements.
>>>>>>
>>>>>> Their 11 element 2m and 432 yagis with all but the front
>>>>>> director the same length did have some directivity but
>>>>>> their poor quality (too wide spaced) gamma match feed took
>>>>>> several DB out of the gain. Most yagi gurus don't like the
>>>>>> gamma match feed accusing it of killing the symmetry of the
>>>>>> yagi pattern and that could probably be applied to the J
>>>>>> feed of Kent's antennas. But on a short yagi the pattern is
>>>>>> going to be wide enough that any asymmetry is going to be
>>>>>> virtually impossible to detect.
>>>>>>
>>>>>> I took a 432 crumcraft with my own very close spaced gamma
>>>>>> match to a CSVHF about 1967 and it didn't give the claimed
>>>>>> gain but was more than 3 dB better than the original
>>>>>> measured at CSVHF. The gang laughed out loud when they
>>>>>> recognized it before it was measured.
>>>>>>>
>>>>>>> The K1FO designs were optimized not only for gain, but
>>>>>>> also for low side lobes and reasonably wide bandwidth,
>>>>>>> and he was the first to effectively optimize all three of
>>>>>>> those parameters. They were a big improvement over the
>>>>>>> NBS designs in that they emphasized important antenna
>>>>>>> properties in addition to gain.
>>>>>>
>>>>>> The were based on DL6WU designs and rarely gained as much
>>>>>> as a whole dB in forward gain.
>>>>>>>
>>>>>>> The NBS antennas lived on through the 90s not as
>>>>>>> marketable antennas, but often as starting points for the
>>>>>>> genetic algorithms that were becoming available then to
>>>>>>> optimize antenna performance. I think the generation of
>>>>>>> CushCraft antennas after the NBS clones, such as the
>>>>>>> 13B2, were done this way, and they were and are good
>>>>>>> antennas for the boom length. There are better antennas
>>>>>>> available now, but the 13B2 speaks to the advance in
>>>>>>> computing power applied to antenna design from the late
>>>>>>> 70s to the early 90s.
>>>>>>>
>>>>>>> YagiCad has no relation to Yagi Optimizer, it is a
>>>>>>> completely different program; essentially a Yagi
>>>>>>> specific front end interface to a NEC computational
>>>>>>> engine. Elements are entered in a spread sheet by
>>>>>>> position on the boom and full element lengths are used.
>>>>>>> It is much improved over generating a bare NEC card deck.
>>>>>>> You should try it out if you have not. It is a very
>>>>>>> useful piece of software. It has its limitations, as do
>>>>>>> most modeling tools, but it gets one pretty far up the
>>>>>>> design curve without a lot of problems. It has an
>>>>>>> optimizer and does scaling, both for frequency and
>>>>>>> element diameter and you can chose several techniques
>>>>>>> for doing this.  It has a genetic optimizer and a
>>>>>>> calculator for various types of matches. If you want to
>>>>>>> do something outside of its limitations, it generates
>>>>>>> .NEC input files which can be used in any NEC or miniNEC
>>>>>>> based tool; barebones NEC, MMana-Gal, EZNec, CocoaNEC, or
>>>>>>> 4NEC2; and it can generate 4NEC2 input files so you can
>>>>>>> use the extended features of 4NEC2 in your modeling. As
>>>>>>> with all modeling tools one needs to study the results of
>>>>>>> the model carefully and make sure that they make sense
>>>>>>> from a physics and physical point. But that is the case
>>>>>>> in any modeling. Try it, I think you will find it
>>>>>>> useful.
>>>>>>>
>>>>>>> I think that there is merit to optimizing G/T, even for
>>>>>>> terrestrial use, although I realize that is not a
>>>>>>> universally held belief. It can make a big difference if
>>>>>>> your neighbor’s plasma TV is on a -10dB side lobe or on a
>>>>>>> -30dB side lobe. For the same boom length, there is a dB
>>>>>>> or more in SNR to be gained with the same length antenna
>>>>>>> by choosing an antenna with a clean design. That is a lot
>>>>>>> to disregard without some thought. I realize that you
>>>>>>> live in the country, so that may be a lesser
>>>>>>> consideration for you, but I think that relying on the
>>>>>>> station on the other end to have an antenna with less
>>>>>>> than optimum properties to work me is asking the station
>>>>>>> on the other end to give up a lot just for my advantage.
>>>>>>> I do agree that having 2 or more short antennas stacked
>>>>>>> vertically is a much better setup for contesting than a
>>>>>>> single long boom antenna. And much better for the rotor.
>>>>>>
>>>>>> My contest Q rate to the cities and to Chicago has gone
>>>>>> down with the adoption of the better G/T antennas, and then
>>>>>> I moved and don't have antennas up on a tower which hurts a
>>>>>> lot too. Some contests I've not even worked my own grid but
>>>>>> I've won certificates with 2 digit scores like the SOLP
>>>>>> class in the whole Midwest Divisioin from home 2015 UHF
>>>>>> contest with 48 points. Definitely a sign of sparce
>>>>>> activity.
>>>>>>>
>>>>>>> Thanks for pointing to me to your paper on stacking and
>>>>>>> the modeled performance of various antennas. It was very
>>>>>>> interesting. I don’t see the modeling of the 12 element
>>>>>>> M2 antenna you referred to in your earlier post in that
>>>>>>> article though; did I miss something obvious?
>>>>>>
>>>>>> I didn't model the 12 element, just the 9 on a boom longer
>>>>>> that K1FO with slightly lower gain.
>>>>>>
>>>>>>> You may want to revisit your modeling of the M2 9
>>>>>>> element antenna. The gain you modeled is over a dB lower
>>>>>>> than the gain I modeled for that antenna when I was doing
>>>>>>> analysis for a friends stack that contains a 2M9SSB. It
>>>>>>> is also about that much lower than the gain for that
>>>>>>> antenna that VE7BQH quotes in his table of modeled Yagi
>>>>>>> data which he generates from several modeling programs
>>>>>>> and which is generally considered an accurate
>>>>>>> representation of the performance of existing antennas. I
>>>>>>> can dig out and send you my .NEC file for that antenna to
>>>>>>> compare with your input file and to check your model
>>>>>>> output. If you want to send me your input file, I would
>>>>>>> like to review that against mine as well to make sure
>>>>>>> that I haven’t made any mistakes. The modeling should be
>>>>>>> consistent, and when it isn’t it helps one’s future
>>>>>>> modeling efforts to find the cause. The modeled gain for
>>>>>>> the 9 element K1FO variant looks about where it should be
>>>>>>> though, so it looks like your Yagi modeling process with
>>>>>>> MMana-Gal is fine.
>>>>>>>
>>>>>>> Keep in touch. - Duffey KK6MC
>>>>>>
>>>>>> Here is the Mmana-Gal 2m9ssb.maa file that I used for my
>>>>>> conclusions. No boom.
>>>>>>
>>>>>>> 2m9ssb * 144.2 ***Wires*** 9 0.250825,	-0.494284,	0.0,
>>>>>>> 0.250825,	0.494284,	0.0,	8.000e-04,	50 0.0127,
>>>>>>> -0.514121, 0.0,	0.0127,	0.514121,	0.0,	8.000e-04,	50
>>>>>>> 0.576263, -0.464434,	0.0,	0.576263,	0.464434,	0.0,
>>>>>>> 8.000e-04,	50 0.873125,	-0.461632,	0.0,	0.873125,
>>>>>>> 0.461632,	0.0,	8.000e-04, 50 1.417637,	-0.463329,	0.0,
>>>>>>> 1.417637,	0.463329,	0.0, 8.000e-04,	50 2.124075,
>>>>>>> -0.456979,	0.0,	2.124075,	0.456979, 0.0,	8.000e-04,	50
>>>>>>> 2.90195,	-0.450629,	0.0,	2.90195, 0.450629,	0.0,
>>>>>>> 8.000e-04,	50 3.762375,	-0.447624,	0.0, 3.76375,
>>>>>>> 0.447624,	0.0,	8.000e-04,	50 4.4323,	-0.450799,	0.0,
>>>>>>> 4.4323,	0.450799,	0.0,	8.000e-04,	50 ***Source*** 1,	1
>>>>>>> 25, 0.0,	1.0 ***Load*** 0,	1 ***Segmentation*** 800,	80,
>>>>>>> 2.0,	1 ***G/H/M/R/AzEl/X*** 0,	0.0,	3,	21.0,	120,	60,
>>>>>>> 0.0 ###Comment### Mod by Gerald N. Johnson, K0CQ
>>>>>>> 1/23/2011 6:19:23 PM Created by Gerald N. Johnson, K0CQ
>>>>>>> 1/23/2011 5:08:08 PM
>>>>>>
>>>>>> In 1983 at CSVHF in Lenaxa KS, W0WL (silent key according
>>>>>> to a recent QST) a long time Collins Radio employee with a
>>>>>> ham radio reputation for doing extremely beautiful
>>>>>> construction work had a NBS 432 yagi made with a square
>>>>>> aluminum boom and aluminum elements welded in place. Looked
>>>>>> beautiful, but on the antenna range was down 5 dB from the
>>>>>> NBS data. Turned out he ignored boom effects and element
>>>>>> diameter effects and used the lengths for wooden boom and
>>>>>> 3/16" elements with a 1" square aluminum boom and 3/8"
>>>>>> diameter elements (IIRC) from an ARRL Handbook. I had my
>>>>>> own version of a NBS standard gain antenna for 432 but it
>>>>>> was too heavy to get up on the pole and near the ground it
>>>>>> had more than 4 dB ground gain over the theory. Two half
>>>>>> waves in front of a 1 wave square reflector or was that a 2
>>>>>> wave reflector? My 7 dBi antenna showed a stronger signal
>>>>>> than Warren's where there should have been about 5 dB the
>>>>>> other way. That really pointed out the importance of boom
>>>>>> effect a
>>>> nd element diameters. Its probably also true that element
>>>> diameter effects the coupling from element to element but NEC
>>>> variations ignore that.
>>>>>>>
>>>>>>>
>>>>>> 73, Jerry, K0CQ
>
>
>