New antenna from Sirio Gain-Master

[Henry HPSD]

Henry, of the antennas you mention only the broadcast dipole is a true center fed antenna. Additionally many FM broadcast stations using these antennas have a TOA below 0 degrees as a result of downward beam tilt. This is done to provide service when the tower is at extreme height over the market area. Granted, this has more to do with coax phasing then antenna type.

I also agree it looks like Sirio has done the modeling in free space mode rather then over true ground. Keep in mind, when they compared the TOA to a 5/8 wave ground plane, the same conditions were used. The model still shows significant improvement with the Gain-Master over the 5/8 wave ground plane.

Shockwave,

Always intresting to have some discussion going on, especially with ones who opinion I appreciated.

I agree with you on:
That one could ask questions if you call a groundplane a center fed antenna.
As a center fed antenna sets your mind that there are two equal parts.
Now, as you’re well aware of each antenna book starts with a vertical dipole then one pole is mirrored in earth then it goes over to a ground plane…it would be the way you look at it.
If one thing is sure, they or not end fed antennas like the A99…that is truly a different feedpoint.
The other antennas I mentioned , antennas like “slappe Arnold”” Sleeve”. etc are true center fed antennas. If they are not then neither would a SGM be to my opinion..and that aint right.

Besides, I didn’t mention vertical polorized yagi’s or Quads for example….do they have a 0 degree TOA? The feeling strikes me that the word gets out…because of the center fed it has a almost 0 degree TOA…that is with what I disagree.

I, tend too disagree with mentioning TOA in reference with Downtilting.

Surely it is difficult to get a sold definition of TOA as it varies with the books you reed, or wich study you follow..
However there is one combined thing wich is stateted in each definition..
That it is compared to a horizontal line (earth)…without earth we don’t call it TOA.
Now downtilting what you are referring too.
As often can be seen for example with GSM telephone communication but i do not rememeber it has anything to do with TOA…that is direct line of sigth communication.
No ground influence….

The freespace patern of a 5/8 wave center fed or either end fed whatever you want in the eleveation plot is 0 degrees…. I can honestly give you more examples then you wish for and each producing 0 degree elevevation plot …Now certainly i do not know all about antennas, neither do the tech guys around me. But we do know something, probarbly more than the average CB user. The question comes to mind is that why do interperted that picture of freespace eleveation Sirio/58wave as false...everyone with a bit of understanding knows these things.....am i missing something ?

And be honest…try the center fed vertical dipole thing with whatever programm you want,
Place the antenna in “real life” and you wont find that 0 degree.
For sure thats briljant marketing but just wont happen.

I couldn’t interpreted your part about the coaxphasing correct, could you briefly specify that for me…

Again, dont get me wrong ...im not bussy with a anti SGM thing...
Im honestly believe that the SGM is a good thing.

What i am trying to do is set things straigth, and perhaps im misunderstanding...
If so...please teach me...!

Again thanks for you input it is highly appriciated,!
Enjoy the weekend,

Henry

 

[Shockwave]

Henry, having taken a closer look at the Slapp Arnold, I agree this is an electrically center fed antenna and is balanced. I don't see the ground plane being quite the same because it is an unbalanced antenna. Perhaps the confusion is in how this is being explained. Simply feeding a radiator in the center may not lower the angle of radiation. However, center feeding the 5/8 wave removes the counterproductive radiation in the lower 1/8 wave portion of the antenna. This may be the key to the lower TOA.

Most of the cellular towers I've seen use mechanical beam tilt because they have multi panel directional antennas that are easy to aim down in all required directions. With FM broadcast the downward beam tilt is done electrically by delaying the signal in the phasing harness to some of the antenna elements. This is not the same thing that is happening with the Gain-Master but one of the new aspects in this antenna must be responsible for the far field gain we are seeing.

 

[Oggy]

Part 3 and 4 Gain Master Video

Hello all. I will in the spring do a final video test of the Shaky VS Gainmaster on the same pole and coax on the same day with my three current reference Operators. (Caine,Carl and Ian). But we have heavy snow now in the North of England, so I guess it will be not that soon. So the current videos are just what I and my Mates found. Not cast iron gospel , but a good insight I feel.Any way enjoy the videos YouTube - Sirio Gain Master VS Shakesphere ABS 1600 Big Stick on 10 Meters Ham Band

 

[Oggy]

Other pssible Ham Bands and Feeder Losses

This is one Robb asked about last week..............73's De Dave M0OGYYouTube - Sirio Gain Master Final Review Video.......Bands Covered and Feeder Losses

 

[TonyV225]

I often wonder about this companies beam antennas.

 

[Robb]

Talked to Marconi/CDX-390 in Houston TX today. He was using the Sirio GM and another antenna. He switched from the GM antenna to another one ("Astro Plane") and asked me which was stronger. Seems the Sirio GM was transmitting better consistently than his other antenna was. Seems to be OK to me.

BTW - Thanks "Oggy" for putting up that video while checking 20, 17, and 15 meter performance on the GM.

 

[CDX-007]

Have had my SGM up for 30 hours now, but it seems to be a defective one.

The red coax coming out from the top of the bottom piece of fiberglass tubing (which is permanently attached to the coil section and has the connector on it) was evidently bent around the rather sharp edge of the top of the fiberglass tube during shipping and had a serious crease in it.

Using a pair of small needle-nose pliers, I gently squeezed against the sides of the crease in a semi-futile attempt to return it to round, then assembled it and erected it anyway.

It's about 1.5 S-units down from the IMAX, and 2 S-units down from the Penetrator at 10 miles, so I believe it to be a bad/defective one.
I'm in the process of emailing Steffania at Sirio to see if I can get the bottom of the antenna replaced.

- Now that I have had an SGM with what I believe are shipping caused issues, I believe Sirio should figure out a way to twist & push that pigtail of coax down into that lower fiberglass tube with tape or something to keep it stuck into the tube but with a string or ?? attached so you could pull it out of the tube after untaping for assembly. - IMH (consumer) Opinion, of course.

...by the way, I'm still infatuated with both the theory of this antenna and the fact that it's the 1st new idea to come along in a decade or three, and I'm not giving up, nor giving in easily!!!

 

[Marconi]

Yep Robb and 007, this is the first vertical antenna that I've heard of really using common mode currents constructively, or so it seems. I guess some would argue the A99 and the Imax are examples too, the only thing with them is I don't believe they are able to balance the antenna as well and be effective at decouple the antenna from the support nearly as well.

You let the cat out of the bag a little Robb, but that's OK.

007, my Gain Master was in a similar condition on arrival!! It had a small crease in the coax where it was bent over the top of the bottom section...and that deformed the coax a little. They did put a little bubble wrap insulation around the coax as it protruded out of the FG, but they had it bent over the fiberglass end...instead of installing it in the box straight out and let it curve around in a bigger loop.

I pushed around on the indention a little with my fingers just like you did, but to little avail. I knew the dielectric inside had been perinatal deformed, maybe not as much as yours was, but still something that should not have happen. I should have taken a picture of the indentation. It looked like someone really pulled it down tight against the end of the 1st section. I saw nothing in the packaging that could have cause such pressure using normal handling. The box also showed no signs of damage in any way, but something put some pressure on this section of the coax and that is not good. I don't think my antenna was damaged as a result however.

You may need to let the antenna blow around in the wind a few days and settle down. I had similar feeling of poor performance after the initial installation, even compared to the A99 which it replaced on a 10' foot mast.

With the tip of the Gain Master about 10' feet higher than the AP the signals are pretty similar...for close-in mobile traffic within maybe 10-15 miles. There are occasional signals 1-2 Sunits in favor of the GM, with most signals about the same, with signals very seldom in favor of the AP. I can't explained the exceptions in signals, but they could be arriving from particular directions or angle maybe.

To tell the truth however, I think my previous comparisons with my A99 installed similarly to the GM vs. the AP...the results were about the same.

I continue to compare signals, but high static activity and a lack of local traffic with my side-band buddies has limited contacts since getting the GM up higher. With cooler and dryer weather...the static becomes an increasing issue around my location.

The things that I definitely can report and that have been reported back on-air to me...is the improved clarity with the audio signals in both directions for DX and local traffic while on the Gain Master. There are several stations at a distance locally that I have difficulty contacting on my AP and that is usualy due to some static or his. However, now I can often make 100% copy with the Gain Master, and on switching antennas my RX meter will typically drop 0-3 Sunits on the GM, just due to the noise level. Let me say however, if my noise is really bad, nothing matters...reception is difficult. To me this is a remarkable benefit that I use to enjoy using my Starduster and for sure don't see with my A99 or Imax. At times I can even flip between antennas and actually copy a station on the GM that I can barely hear on the AP and I've always considered the AP's one of the quietest antennas I have.

I'm impressed for these reasons alone and with no radials it is a dream to install, and no tuning. I think this one will sell like hot-cakes even without higer power levels available. I also think that without ferrels on the FG tubes the antenna may prove to be much more durable even with the added length.

 

[CDX-007]

Well, in my opinion there's no excuse for not seeing this problem with packing / shipping ahead of time.

I imagine what happens is the antenna-in-box is tossed around by the shippers and when it is sent spearheading into the wall of the truck or the shipping building and stops suddenly against something substantial, it sends the tube flying against the inner wall of the box and crushes the coax stub between it and the sharp edge of the tube, something mere bubble wrap cannot prevent.

The better way to pack would be to attach a string or ?? to the end of the coax stub, just below the connector, and gently push & twist the coax into the tube with tape over the end of the tube to prevent the coax from falling out until it is intentionally removed by the consumer for assembly.

Having such high expectations, I'm rather disappointed that such a minor detail has caused what I believe is a severe degradation in functionality, especially when it could have been so easily prevented, but I am still reserving high hopes for this antenna once/if I have mine replaced with a fresh base.

 

[Marconi]

I think you're right 007. If the box was stored on the worst end...the coax might get compressed just by the shear weight of the bottom section of the antenna. They can't make the pig-tail straight like I suggested earlier, but they can pad the top to better protect the cable.

Typically damage such as this makes a bump in the impedance and should be detected with an SWR check maybe. How does the SWR look.

I ran my analyzer on mine with the following results:

Analyzer Bandwidth 2.0:1< 31.000 to 25.380 = 5.62 mhz @ 31' feet.

2 resonance points at:
28.230 = 1.30 SWR R=50 X=+12 Z=51
27.205 = 1.23 SWR R=52 X=+10 Z=55
26.300 = 1.21 SWR R=53 X=+8 Z=54

Daiwa CN802H shows SWR on inline meter shows @ 10% RF thru a 27.205 mhz tuned 1/2 wave cable @ 55' of Cable Experts RG8/U @ 77% VF measured on my Autek:

23.890 12w 2.00
26.600 12w 1.01<
27.205 12w 1.01
28.560 12w 1.00>
29.999 12w 1.90

These results are pretty similar to what Sirio states in their specs.

When I first setup my GM on a 10' mast I did one signal check with a radio Buddie and he reported 2 Sunits less signal on the Gain Mast (3) vs. the AstroPlane (5) @ 45' feet to the tip.

After raising the Gain Master up on a new mount @ 55' feet to the tip, with the coax connector still about 9' below the feed point on the AP we just now checked signals again. The Gain Master now shows (8) vs. AstroPlane (5). We may be about 10+ miles apart as the crow flies.

 

[jazzsinger]

2 resonance points at:
28.230 = 1.30 SWR R=50 X=+12 Z=51
27.205 = 1.23 SWR R=52 X=+10 Z=55
26.300 = 1.21 SWR R=53 X=+8 Z=54

i'm not understanding your ,"2 resonant points statement"

None of those are resonant points Eddie, at resonance X (reactance) = 0,

R (resistance) can equal anything at resonance depending on the design of the antenna.

common characteristic feed resistances would be 36 ohms [1/4 wave gp],
72 ohms [dipole] , approx 54 ohms [starduster], 50 ohms [silver rod,5/8 waves etc, due to being shunt fed and tapped on coil at 50 ohm point]

When the antenna is resonant Z (impedance) will be the sum of the antennas characteristic feed resistance + 0 reactance.

 

[CDX-007]

I think you're right 007. If the box was stored on the worst end...the coax might get compressed just by the shear weight of the bottom section of the antenna. They can't make the pig-tail straight like I suggested earlier, but they can pad the top to better protect the cable.

Typically damage such as this makes a bump in the impedance and should be detected with an SWR check maybe. How does the SWR look.

I ran my analyzer on mine with the following results:

Analyzer Bandwidth 2.0:1< 31.000 to 25.380 = 5.62 mhz @ 31' feet.

2 resonance points at:
28.230 = 1.30 SWR R=50 X=+12 Z=51
27.205 = 1.23 SWR R=52 X=+10 Z=55
26.300 = 1.21 SWR R=53 X=+8 Z=54

Daiwa CN802H shows SWR on inline meter shows @ 10% RF thru a 27.205 mhz tuned 1/2 wave cable @ 55' of Cable Experts RG8/U @ 77% VF measured on my Autek:

23.890 12w 2.00
26.600 12w 1.01<
27.205 12w 1.01
28.560 12w 1.00>
29.999 12w 1.90

These results are pretty similar to what Sirio states in their specs.

When I first setup my GM on a 10' mast I did one signal check with a radio Buddie and he reported 2 Sunits less signal on the Gain Mast (3) vs. the AstroPlane (5) @ 45' feet to the tip.

After raising the Gain Master up on a new mount @ 55' feet to the tip, with the coax connector still about 9' below the feed point on the AP we just now checked signals again. The Gain Master now shows (8) vs. AstroPlane (5). We may be about 10+ miles apart as the crow flies.

I presume the SGM is doing just what Sirio claims and, just as a ¼ wave is best for a location down in a canyon or behind hills due to it's high TOA getting over local hills, trees & buildings, perhaps the lower TOA of the SGM might actually hurt one's signal strength if not mounted high enough to take advantage of the flatter TOA.

I wouldn't be surprised if that's what was happening in your 1st comparison.

 

[Oggy]

Have had my SGM up for 30 hours now, but it seems to be a defective one.

The red coax coming out from the top of the bottom piece of fiberglass tubing (which is permanently attached to the coil section and has the connector on it) was evidently bent around the rather sharp edge of the top of the fiberglass tube during shipping and had a serious crease in it.

Using a pair of small needle-nose pliers, I gently squeezed against the sides of the crease in a semi-futile attempt to return it to round, then assembled it and erected it anyway.

It's about 1.5 S-units down from the IMAX, and 2 S-units down from the Penetrator at 10 miles, so I believe it to be a bad/defective one.
I'm in the process of emailing Steffania at Sirio to see if I can get the bottom of the antenna replaced.

- Now that I have had an SGM with what I believe are shipping caused issues, I believe Sirio should figure out a way to twist & push that pigtail of coax down into that lower fiberglass tube with tape or something to keep it stuck into the tube but with a string or ?? attached so you could pull it out of the tube after untaping for assembly. - IMH (consumer) Opinion, of course.

...by the way, I'm still infatuated with both the theory of this antenna and the fact that it's the 1st new idea to come along in a decade or three, and I'm not giving up, nor giving in easily!!!

I'm sorry to hear this issue Scott. I know with my dealings with Stefania @ Sirio they won't let you down. I'm pleased now that a few of our American friends are now testing it. I now know another local guy (Carl on the video) who has replaced his Antron 99 with it and seen a big improvement.......with "S2" less white noise and static. There is a guy in Sweden who got a GM around 2 months ago and had the GM on the same pole as an A99,Imax 2000,and a Sirio 827 and he says it works better than them all. He has posted on the Charlie Tango DX group forum in the last few days.So keep up the reports guys.

 

[Oggy]

Talked to Marconi/CDX-390 in Houston TX today. He was using the Sirio GM and another antenna. He switched from the GM antenna to another one ("Astro Plane") and asked me which was stronger. Seems the Sirio GM was transmitting better consistently than his other antenna was. Seems to be OK to me.

BTW - Thanks "Oggy" for putting up that video while checking 20, 17, and 15 meter performance on the GM.

Not a problem Robb.......Glad to help

 

[CDX-007]

Dave, what level of improvement in signal increase, both RX & TX, has Carl seen on the SGM over the A99?