New antenna from Sirio Gain-Master

[RadioDaze]

Ok interesting... I was under the impression that a 1/2 wave was a 1/2 wave was a 1/2 wave.

I have a basic 1/2 wave silver rod here and it works quite well at 6M it has to be said.

This leaves me wondering if a Solarcon MAX2000 would perform as well or better as the GM in my specific height situation.

I have an aluminium sectional slot together swaged mast type, each tube is 1.5M... I normally do 4 giving me 6M (19ft) above ground. On very very low wind days I can do 5 sections giving me 7.5M (24ft)

Is 19ft deemed too low for a GM to realize best performance ? (Given your own experience it would seem so)

I tend to go into vertical antennas fairly deep cause I do not use a beam and hanker for the absolute best performance given my various mounting methods and restrictions. It may be that different antennas suit different mounting options I have at various QTH's, but as a rule 6M mast is typical for most of my mobile set ups.

At what height would the Gain Master start performing to spec i.e. realizing close to that advertised 0 degree take off angle?

 

[M0GVZ]

I have a local friend that uses the analog meter on his Pro3 and I've got him well trained! - LoL!!

He had me on the Penetrator at S-9+1dB, all day, everyday for months.

Ah so its a typical CB claim then because you cannot measure 1 or 2dB on that meter. S points yes, down to a single dB, not really.

I don't even know how the hell you'd measure 1dB above S9 on a Pro3 meter given the gap between the marks for S9 to S9+10dB is roughly the same as S8 to S9.

 

[hotrod]

Ah so its a typical CB claim then because you cannot measure 1 or 2dB on that meter. S points yes, down to a single dB, not really.

I don't even know how the hell you'd measure 1dB above S9 on a Pro3 meter given the gap between the marks for S9 to S9+10dB is roughly the same as S8 to S9.

i will say this gotta local here with a imax @ 70ft to pl259. and a 827 around 30-35 ish ft to pl259. and the imax struggles to keep up. i just laugh.also got another local that has a GM and imax and super scanner. and his GM shows very little [if any] differenceall mounted 30 feed to base of antenna

 

[RadioDaze]

i will say this gotta local here with a imax @ 70ft to pl259. and a 827 around 30-35 ish ft to pl259. and the imax struggles to keep up. i just laugh.also got another local that has a GM and imax and super scanner. and his GM shows very little [if any] differenceall mounted 30 feed to base of antenna

I think the Imax 2000 really needs a very substantial ground plane (given it ships with none !). It makes sense the 827 blew it away... lower loss coil (very thick and substantial), quality materials.. plenty of metal and mor radials than most. With any QTH I think you need to set up and test with 1 antenna on 1 mast in your exact location and see what happens.

Maybe the GM was close to other antennas, being the balanced antenna it is as has been mentioned as close to clear free space is important to maintaining reported specs.

Every vertical will work but there will be small differences depending on exact environment it seems.

I really would like some response to how high before the Gain Master (or any dipole) needs to be from the ground to counter ground losses and pattern interference from nearby objects.

Anyone got any 1/2 wave vertical (online seems to be mainly horizontal) dipole models at various heights to share. Might be able to follow that as a guide for the Gain Master.

I am curious to know if a ground plane antenna of some variant will outperform the GM when 1 wavelength of height is not possible. Given a 1/2 wave can DX at 16 degree TOA at 0.5 M

It is ambiguous if a GM could outperform that at that height.

 

[RadioDaze]

I found one : ).... scroll to the bottom of the page you can see the elevation lobe change as dipole height reaches through 0.5, 10, 20, 30, and 40 ft... interesting.. so you need a vertical dipole to be at 40ft to realize best performance at low angle at least.

http://ac6la.com/aecollection5.html

I cannot even get my GM to 30ft so now I am wondering if it can be beaten at 20ft/24ft by a 1/2 wave or 5/8 wave antenna or even a 1/4 wave GPA (with 1/4 wave radials). I think actual experiments need to occur now.

Not clear cut this antenna business is it ?

(My QTH's being a static mobile base station have different antenna mount options depending on how much physical energy I have on the day (sometimes I go GM on 5 poles, sometime just 3, sometimes 1/2 wave clamped to a gate... it would seem that models suggest that a 1/2 wave vertical at low height i.e. 0.7M clamped to a gate... with a decent ground plane will outperform balance dipole type antennas at the same low height. This is a good information as I have a very large steel gate on which I can put a ground plane 5/8 or 1/2 wave antenna (G clamped directly). So when I am looking for a quick set up the standard or 1/2 wave will likely have a lower TOA than a Gain Master bolted to the gate. All antennas (including the GM) SWR up ok 1.3:1 or less directly clamped to the gate but that suggests nothing of TOA's. I am going to create another set of radials crossing the gate out of aluminium poles and G clamp them horizontally to further balance and increase ground plane when I use typical/basic 1/2 and 5/8 antennas.)

 

[M0GVZ]

Not clear cut this antenna business is it ?

The beauty is that antenna theory is well understood which is why you can get antenna modelling software that is quite accurate even at home user level.

The downside is that there's a hell of a lot to learn, basically the result of a century's worth of research, investigations and experimentation and its hard if not impossible to know it all. I took a keen interest in inverted L's at one point and spent a whole load of time researching those so I have a reasonable idea of how they work, what effects altering the ratio of height to length is etc and I've had a similar level of interest with mobile operating and installation. I've not really done much with yagis at all so my knowledge of things like how changing spacing between various elements effects gain and f/b is rudimentary.

For those interested in learning, the ARRL do an excellent antenna book.

http://www.arrl.org/arrl-antenna-book

It is $49.95 but is a thick 936 page book which comes with a CDROM that also has a version of the EZNEC modelling software as well as models for many of the antennas in the book. It doesn't just focus on the antenna but the complete antenna system so covers things like grounding, mounts, towers etc as well as antenna designs and how they function. Most of the antennas in the book can be built at home. For anyone with an interest in antennas, even if its just restricted to vertical mono element ones, it is certainly one well worth having on the shelf.

 

[hotrod]

I think the Imax 2000 really needs a very substantial ground plane (given it ships with none !). It makes sense the 827 blew it away... lower loss coil (very thick and substantial), quality materials.. plenty of metal and mor radials than most. With any QTH I think you need to set up and test with 1 antenna on 1 mast in your exact location and see what happens.

Maybe the GM was close to other antennas, being the balanced antenna it is as has been mentioned as close to clear free space is important to maintaining reported specs.

Every vertical will work but there will be small differences depending on exact environment it seems.

I really would like some response to how high before the Gain Master (or any dipole) needs to be from the ground to counter ground losses and pattern interference from nearby objects.

Anyone got any 1/2 wave vertical (online seems to be mainly horizontal) dipole models at various heights to share. Might be able to follow that as a guide for the Gain Master.

I am curious to know if a ground plane antenna of some variant will outperform the GM when 1 wavelength of height is not possible. Given a 1/2 wave can DX at 16 degree TOA at 0.5 M

It is ambiguous if a GM could outperform that at that height.

i agree completely. i was just giving local testing results.far as how high i belive sirio recommends min of 20 feet above ground. if i did the math right. sirios home page tells ya if ya look up gain master.

 

[RadioDaze]

Thanks for the info on the antenna book. Might be one book worth having.

Well that's not too bad... 20ft. I can do 20ft no issues normally... 24ft also no worries on a calm day.

Now for some experiments.

They say...minimum 3 meters in the Sirio GM manual. I suspect that might be for getting the SWR to a decent level against the side of a house roof.

In practice I can bolt the GM to a huge metal gate and get a 1.3:1 SWR that's 0.7M but as mentioned says nothing of TOA which probably will suffer compared to a GPA type 1/2 or 5/8 wave bolted to it which should work well (and has done in practice)

Experiments !

 

[M0GVZ]

Experiments !

Build yourself a simple field strength meter - plenty of simple circuits on the net. Doesn't need to have an accurate scale on it, you're just going to use it for comparisons so it can literally have 1 2 3 4 5 on the scale - you could even use a spare CB radio meter.

Stick it on a pole and with the radio in TX and at a bit of a distance away from the antenna (several feet to yards - distance will depend on sensitivity of your meter and ERP of the antenna), slowly raise the meter from the ground and watch the needle go up and down. Rinse and repeat for different antenna heights. You won't get a measurement of dB but it'll show you where the lobes and nulls are in the vertical plane and you'll be able to see the angles of those raise and lower as the height changes.

 

[RadioDaze]

Build yourself a simple field strength meter - plenty of simple circuits on the net. Doesn't need to have an accurate scale on it, you're just going to use it for comparisons so it can literally have 1 2 3 4 5 on the scale - you could even use a spare CB radio meter.

Stick it on a pole and with the radio in TX and at a bit of a distance away from the antenna (several feet to yards - distance will depend on sensitivity of your meter and ERP of the antenna), slowly raise the meter from the ground and watch the needle go up and down. Rinse and repeat for different antenna heights. You won't get a measurement of dB but it'll show you where the lobes and nulls are in the vertical plane and you'll be able to see the angles of those raise and lower as the height changes.

That sounds interesting but if the antenna in on a 6M pole how will I get to the top to measure ?

Sounds a bit tricky.

 

[M0GVZ]

That sounds interesting but if the antenna in on a 6M pole how will I get to the top to measure ?

Sounds a bit tricky.

Long pole. Never said it'd be easy.

 

[RadioDaze]

Don't think I can do that, long pole and another one with a phone on it videoing what the meter says. Just seems grossly impractical. Thanks anyway. I actually recall I have a field strength meter in my SWR meter.

 

[hotrod]

Don't think I can do that, long pole and another one with a phone on it videoing what the meter says. Just seems grossly impractical. Thanks anyway. I actually recall I have a field strength meter in my SWR meter.

did you ever get a gainmaster yet???

 

[222DBFL]

Yes, RadioDaze has a GM and uses it as a static mobile setup. He even posted a thread about how he puts it together and such in the field. He says it's a good antenna. I beleive he uses the GM & an IMAX2000 currently. He switches back and forth between them.

 

[RadioDaze2.0]

That's correct... here is how I get it light and easy for mobile static.



I have not had much radio time the last weeks, very busy workload meaning all work and no play. Will hope to get out there again soon.