New antenna from Sirio Gain-Master

[BOOTY MONSTER]

007 have you ever compared penetrator to penetrator with one being 5/8wl and the other being .64wl and then swapping their places to see if the coax or location or reflection was causing the difference ? im guessing you have but im asking to eliminate them as performance factors .

 

[AudioShockwav]

It is not easy and maybe WWRF doesn't even like this type of info posted, because I'm sure it takes up space. If this is true, them let me know and I will have to send you the files via email. Robb how say you?

Post away We are not worried about using too much space.

73
Jeff

 

[Marconi]

I have posted the short 5/8 wave and the regular length 5/8 wave in my album.

These models are not presented for accuracy, as I don't have the knowledge to know the difference if I would see it. Personally I don't think modeling really gives real results accurately, and I can't speak for any program as being better or not. To me these models look to be close to the dimensions of the real antenna, but again they are not matched, tapered, and I don't use all the features this program can provide. My main shortcoming would be the lack of segments. Like I said I tested one of my 5/8 wave 2 meter antennas against some published Eznec test results and my results were very similar. Until someone verifies this work, I don't promise anything but something to look at.

BTW, if you recall Henry's model of a Vector, it was decided that the model had to be done with thin wires in the input or else little or no gain could result. I have tweaked Henry's model and I think I may have found the problem, but again someone else will have to do some verification work.

Here are the links to my album. I have not added captions to the models yet.

http://www.worldwidedx.com/members/marconi-albums-i-10k-short-625-tubing.html

http://www.worldwidedx.com/members/marconi-albums-i-10k-tubing-625-length.html

Thanks Jeff.

 

[CDX-007]

007 have you ever compared penetrator to penetrator with one being 5/8wl and the other being .64wl and then swapping their places to see if the coax or location or reflection was causing the difference ? im guessing you have but im asking to eliminate them as performance factors .

Well, since that would require redesigning the match so it could tune at 5/8 / .625wl, no I haven't.

However, I have done tests with other 5/8 (I own a 1975 Sigma5/8 & have owned a I-10K & Wilson Alpha V-5/8) and made darn certain I was keeping the better performer / built antenna.
The 5/8 of all types were close performers to the P500, especially more locally, as within ~12-15 miles, but I preferred the construction of the Hy-gain Penetrator over all the others, except the I-10K.

As far as not keeping the I-10K, I've never met Jay but I feel somewhat of a kinship and appreciation for someone who would also realize the quality of the P500 and would go to the trouble and take the time required for as many mods and prototypes along a similar vein as he has displayed.

THE CONSTRUCTION QUALITY OF THE I-10K IS OUTSTANDING, making other antennas like the Maco V-5/8 seem like an inexpensive R/S mobile antenna by comparison, and as far as the I-10K performance, I appreciate how well it keeps up with the construction of that excellent antenna.

I wonder if/when he'll bring out a .64 version, though it's not hard to simply tune it to .64 as I finally did when I attained similar S-readings to that of the P500 @ ~85miles.

 

[Marconi]

I find this very interesting that a change of a few inches in radiator length would drop the TOA by an additional 8 degrees. Many years ago I had a conversation with a colleague concerning the possibility of downward beam tilt with a single element FM antenna. He suggested it was possible to manipulate the take off angle by adjusting the radiator length. The change of 8 degrees is more then I expected because I have not seen that much difference working with the Sigma design.

Also, the differences in the matching network required for a .625 wave and a .64 wave are nearly identical. Only a slight change in the tap point should be required to match either one. One reason companies are using the free space model is because it eliminates variables with the height the antenna is mounted above ground.

This result surprised me too. If you compare my wires view you will see the antennas are the same except for the overall length. When I'm tweaking these antennas I watch the Source Data report and the Currents report. I noticed a dramatic change in currents with a fractional adjustment I made to the length of the .625 overall set at 22.6' feet at some point just longer and the gain went down. That too surprised me. Then I started shortening the radiator length and the gain began to rise at every point for almost 2' feet shorter in length. I can't figure it out. The antenna is very simple.

I Just add a mast to the antenna, but I haven't tried to duplicate the changes yet. Adding the mast improves the gain figures even more and isolating the mast from the antenna makes the gain go down. That is what I see.

 

[HomerBB]

Back to the length. Give me a really good reason to want to change the length. Keep saying things like better TOA. Do that, and I'll end up shortening the 5/8 and retapping the coil by Friday.

Now there would be a great comparison idea! I'd LOVE to see if your results mirror mine.

I'm off on Friday. Weather notwithstanding I may be able to make the changes. Up and down with the tip-over tower two or three times ought to get the job done. . .

 

[Shockwave]

I Just add a mast to the antenna, but I haven't tried to duplicate the changes yet. Adding the mast improves the gain figures even more and isolating the mast from the antenna makes the gain go down. That is what I see.

I hate to go out on a limb and suggest EZNEC may not be the most accurate tool. Sirio uses CST Microwave Studio for a reason. The engineers at Sirio are certain the radiation by the mast on a 5/8 wave groundplane is counterproductive to gain on the horizon. The explanation went on to say this is the exact opposite effect with the Vector. In the case of the Vector, mast radiation reinforces gain on the horizon.

Before anyone says different length masts will have different effects due to wavelength and phase, those variables do have an effect. However the most important part of mast radiation to consider is the section of mast that meets the antenna. Here the radiation currents are the highest and depending on the phase at this point will determine if the mast radiation is beneficial or not.

It seems like EZNEC does a great job comparing how different antenna designs would work. It may not have enough accuracy to predict the differences slight changes in length make in order to peak the gain of a particular antenna. I've seen several cases now where EZNEC told me to do one thing while a signal test 50 miles out told me to do the opposite. Computer models are still new to me and I haven't been able to get them to replace open field signal tests at one wavelength above ground and 50 miles range.

 

[CDX-007]

I'm off on Friday. Weather notwithstanding I may be able to make the changes. Up and down with the tip-over tower two or three times ought to get the job done. . .

- Especially if you sneak a .64wl comparison in there somewhere... :drool:

I hate to go out on a limb and suggest EZNEC may not be the most accurate tool. Sirio uses CST Microwave Studio for a reason. [My emphasis.] The engineers at Sirio are certain the radiation by the mast on a 5/8 wave groundplane is counterproductive to gain on the horizon. The explanation went on to say this is the exact opposite effect with the Vector. In the case of the Vector, mast radiation reinforces gain on the horizon.

Before anyone says different length masts will have different effects due to wavelength and phase, those variables do have an effect. However the most important part of mast radiation to consider is the section of mast that meets the antenna. Here the radiation currents are the highest and depending on the phase at this point will determine if the mast radiation is beneficial or not.

It seems like EZNEC does a great job comparing how different antenna designs would work. It may not have enough accuracy to predict the differences slight changes in length make in order to peak the gain of a particular antenna. I've seen several cases now where EZNEC told me to do one thing while a signal test 50 miles out told me to do the opposite. Computer models are still new to me and I haven't been able to get them to replace open field signal tests at one wavelength above ground and 50 miles range.

Anyone surprised that I agree?

Hello Lightfoot .........nice to finaly post on the Worldwide Radio Forum. I have had mine (got it direct from Sirio in Italy) around a week ago. Due to my job ,it will be a couple of weeks before I do my side by side with it. As I said on my video, I feel it's well built .I think it will work very well and I guess, this is what will make it worthwile for most. For most in the UK 500 Watts is plenty. But I know Stateside your like your power, so I guess this may be a bit of a down side for you guys.......I do intend running it QRO on 10 meters too....The UK Waving A Hand!!....Dave M0OGY (26CT110)

Dave, you might want to get on it or I might beat you to the punch!!

...if they ever show up here in the flat broke USA.

 

[Henry HPSD]

Shockwave,

Just some thougths...
if the mast gives additional gain to the horizon could that be a indication of less than ideal counterpoise? As that seems to do the same.

Did your eznec models included coax/the rigth conductivity/matching system/mast etc?
Probarbly did but just wondering as i noticed different results with those.

What i know for a fact is that enzec pro (using the NEC4 engine) gives sligthly different results.
Gain migth be of with 0,1dB but the biggest problem i had was with SWR.
Where Nec2 predicted flat Nec4 predicted 1:1.5 wich was rigth.

You can easily verify your "length" statement with Roy lewallen, as he is always very polite in returning emails.

How did you measure by the way such a small gain difference?
As for my own measuring equipment..
with certaincy i can narrow it down to about 0.5dB.
I can not imagine a couple inches on the 5/8 wave would make such a difference.
So i am intrested in how u measure difference smaller than 0.5 with accuracy?, tnx in advance!

What i can say about eznec is that we have done tests with professional measuring equipment from R&S. (sadly not mine :-( )
And each time the results were spot on. now i do have to say those results were based on Nec 4 not Nec2. What i can do perhaps is try again in May when we do the test runs again
and verify those with nec2...although differences in gain are often very very very small.
Now, those were absolute gain measurments. Ofcourse in real life radiation patterns vary due to local influence. Perhaps that is what is happening with your case aswell.
although if so...i cant imagine results are always lower...as that would indicate a "pattern".
Perhaps intresting to mention: those measurments who were fault came either to human constructing error. Or, Like a old 70cm antenna...it did a couple dB more gain when it was polished again..makes u wonder...

See u guys soon around,

Henry
11 meter Dx antenna systemx

 

[Oggy]

- Especially if you sneak a .64wl comparison in there somewhere... :drool:



Anyone surprised that I agree?



Dave, you might want to get on it or I might beat you to the punch!!

...if they ever show up here in the flat broke USA.

Well we'll see Mate,but i'll be the one with the Bigstick comparison.....good luck

 

[Shockwave]

Henry brings up an interesting point regarding the possibility of the mast benefiting as the result of a less then ideal counterpoise. However if this was the only factor effecting gain it would be difficult for the mast to reduce gain on a vertical antenna. It's more then just adding counterpoise or not. It comes down to what the phase of the radiation currents will be below the feedpoint where the mast meets the antenna. This is determined by the design of the antenna.

When I attach the Sigma FM design to the top of any length mast I see gain go up. Sirio says that won't happen with a 5/8 wave ground plane. I borrow a Potomac FIM-71 when I need to compare the gain of my FM antenna to it's internal calibrated half wave dipole. That is the only time I use this meter. All of my gain peaking is done with a Marantz FM receiver with a DVM connected to it's analog meter and RF attenuators on the front end RF amp. I also modified the input impedance to the receiver from 75 to 50 ohms. It makes it so much easier to compare digital numbers while peaking gain.

I have EZNEC+ and will admit I don't know how to use it very well. I'm still old school and do almost everything with in the field signal testing. If you have a better model of the Sigma antenna then the one you first sent me I would very much like to see it Henry. It takes me so much longer to make improvements with the model being in unfamiliar territory. All I can really do is peak lengths. I can add a mast but I can't simulate the loop or a gamma match.

Recently I did some far field signal tests on FM against a non commercial vertically polarized signal. It shows more far field gain once again with a loop larger then 1/4 wave and radials shorter then 1/4 wave with a radiator length about 7/8 wavelength physically. I still want to try a different receiving location to make sure the results stay the same in the field.

 

[Robb]

This was sent to me from "dxswe" by proxy this morning:

I have the antenna up and working yesterday in 4 hours:

honduras
costa rica
jamaica
bahamas
usa
canada
paraguay
brazil
argentina

YouTube - 121IR073 Mr.Jermaine (TEST Gain Master 5/8) +15Db

 

[simonradioman]

Hello Guys this is my antenna and my test began yesterday with it. Sure conditions were good but had the antenna made and these were the results so far, and more tests over the weekend. Well made it is, fiddly and not an antenna for taking out and to keep rebuilding as it will not last long am sure. The exact dimensions they mention 1800m between two clips that hold the antenna is important and a few mm each way and the antenna does not respond well to it.

Will be more videos later when time and on the same page

Regards from Munich

Simon

 

[Robb]

Hello everyone from the UK. I see you posted my video on here. I do intend to do a side by side with my Shakesphere ABS1600 Bigstick within the next couple of weeks. I'm curious Robb why my video makes the GM look shoddy?.....73's Dave

Your video is fine. The tubing of this antenna just looks like it has very thin walls; that is what looks 'shoddy'. Looks weak. That is what I take issue with. Due to its length, it looks like a medium or strong wind may shatter it. It is just the impression I got from looking at it - 'uber alles'.

 

[Oggy]

Your video is fine. The tubing of this antenna just looks like it has very thin walls; that is what looks 'shoddy'. Looks weak. That is what I take issue with. Due to its length, it looks like a medium or strong wind may shatter it. It is just the impression I got from looking at it - 'uber alles'.

OK Robb ,no problem. The tubing wall thickness is around 3MM on all four sections. I feel the antenna is well built and the fibreglass is far better quality than a Solarcon product. I guess going up to 5MM would add to the weight to much..........73's Dave