Not enough difference to take down a good 5/8 wave groundplane that is working to your satisfaction is something I'll agree on. The horizontal dipole correctly mounted will work skywave DX better then any of these vertical sticks too. But no dipole mounted vertical is going to work other vertical stations at 50 plus miles like the GM or Vector.
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gainmaster vs i10k a quick test with locals
- Thread starter bob85
- Start date
Not enough difference to take down a good 5/8 wave groundplane that is working to your satisfaction is something I'll agree on. The horizontal dipole correctly mounted will work skywave DX better then any of these vertical sticks too. But no dipole mounted vertical is going to work other vertical stations at 50 plus miles like the GM or Vector.
Meglatron, the only reason I feel the GM seems to be ill-affected when low to the Earth is because I experienced poor results compared to my TopOne and my A99 mounted on the same 10' mast and I recall several others saying something similar, including Shockwave telling us that he was not impressed with his first test, and I think that too was at a low height.
I wondered how I could determine that at some point and that is when I scanned a Bandwidth Curve Report with the antenna at about 11' feet high and I recall it didn't seem to me to be very responsive even on a 20' foot mast. Here are all the BW curves I have done with my GM since I got it. I probably did one with each installation, and for sure when I changed the feed line or placed it on a different mount at my location.
I haven't spent much time considering what these reports my indicated, but note how irregular the analyzer BW curve report is at 11' feet, and the difference between SWR BW curves mounted out back vs. those mounted near my shack. There might even be some differences to be noted using different feed lines, but this is why I conclude that the GM may be ill-affected when mounted low to the Earth or close to other stuff.
View attachment Bandwidth curves for Gain Master.pdf
BTW, I tend to agree with SW, regarding his comment about nearby signals. I tend to see the same here at my location. Of course if Bob comes back and tells us that all his reported contacts were signals 30 - 90 miles away, then I guess such an idea is off base.
In that case i use my beam, a 3 element beam with a 6db gain and 1 s unit gain over the dipole is a very good performer for local communications. Here again i would think I am better off upgrading coax.
Bob says in his first post that this is "a quick test with locals". I only looked at Bob's receive tests. It's clear he took the time to measure much more accurately then those on the other end. Looking at the signals with the open RF gain I suspect we could see an opposite affect if they started out with just barley moving the meter.
I think thats what Sirio has claimed from the beginning gain on the horizon if people expect to see some great signal change from someone say 15-20 miles away don't get your hopes up. The longer antennas start to shine the further away you get, as the lower angle of radiaton starts to take over. Remember where antennas get "gain" from: By focusing radiation into specific areas, while losing radiation from others.
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shockwave, im sure if the receiving stations had left their rf gain open they would have seen notably less change at their end,
these were local stations nobody over 15 miles and the ones on the list closer than that, we had reports from more people from different directions with the same results, small advantage at that height to the i10k, if the antennas had been up high the results could well be different,
the guy who bought the gainmaster only talks local with his antenna low, he is very happy with his gm compared to his a99.
these were local stations nobody over 15 miles and the ones on the list closer than that, we had reports from more people from different directions with the same results, small advantage at that height to the i10k, if the antennas had been up high the results could well be different,
the guy who bought the gainmaster only talks local with his antenna low, he is very happy with his gm compared to his a99.
the test was only a quick test done at about 12 feet, it was a nice day so we decided to do a test before errecting the gm at its new home a similar distance above ground, its possibly not what somebody with a tower would see but it gives my locals an idea of what to expect locally in a typical install here,
we also compared the gm to the a99 at its new location, the gm improved signals by about 1 s-unit over the a99, i could hear on my way home without looking at the meter that the gm filled in the hills and hollows notably better than the a99,
eddie, i lay the antenna down well away so as to minimise any effect there could be, i have done that for over 25 years,
a question was asked could the aluminum stepladders be having an effect so a local walked around the yard holding the stepladders while we watched to see if the ladders effected the signal, they don't seem to be a problem.
booty, i already know the outcome of that test in this yard if the NAPCO works as well as my hybrid
the gainmaster did better than my no radial imax in the same test, a couple of local imax users assisting in the install have already decided the gm will be their next antenna.
Bob at first I thought that your bud brought his new GM over to your house to compare it to your I-10K. But apparently you took your I-10K over to his place.
Are you planning for a new antenna or some more experimenting? I sure hope you will be putting up your best antenna, the modified Vector.
BTW what is the NAPCO?
I'm just taking my break so I have to make this quik, but to me it seems the lower angel antenna would even be stronger close in if it was up high enough like it will be on my 71 feet tower thois weekend. to me it seems that if it concentrates the power into a smaller beam then it would hit harder everywhere if things werent in the way. got to go
eddie
they came to me with his gm then we went to his and installed the gm in place of his a99, it was not my idea, they asked if i wanted to test the gm against my i10k before we put it up at the owners house,
people round here help each other with antennas and tests, more so when its something different we have not seen before, started with 3 of us then two more locals joined in while others waited on ch16 with their rf gains backed down,
the only antenna in the pipeline at the moment is my modded sigma4 aka ( napco) i found my hub pieces, they need some work,
we are modding a few sirio 827's with machined hubs to take 1/4wave radials, not sure how that will go.
they came to me with his gm then we went to his and installed the gm in place of his a99, it was not my idea, they asked if i wanted to test the gm against my i10k before we put it up at the owners house,
people round here help each other with antennas and tests, more so when its something different we have not seen before, started with 3 of us then two more locals joined in while others waited on ch16 with their rf gains backed down,
the only antenna in the pipeline at the moment is my modded sigma4 aka ( napco) i found my hub pieces, they need some work,
we are modding a few sirio 827's with machined hubs to take 1/4wave radials, not sure how that will go.
Except that a local stations antenna will be more responsive to radiation angles that are not tightly focused on the horizon. There is the reason why high gain verticals show their advantage in the distance and not locally. Think of the old doughnut analogy as the signal around your vertical antenna. Squash the doughnut down with your foot and the mass extends outward further at the expense of mass closer in. In order to achieve gain in any antenna we have to take signal from where it's not needed and place it where it's desired. The vertical beam can increase signal both locally and in the distance since it takes energy from other directions to refocus it in one as opposed to the squashed doughnut affect.
Very interesting. What angles would you say work best for 5, 10 or 15 miles?
Thanks.
When it comes to line of sight contacts, having the angle of radiation close to 0 degrees is a benefit. This is true even if the other station is only a mile away. We would not want to change the angle from 0 degrees to increase a local signal unless there were extreme differences in elevation. Actually achieving 0 degrees over real earth on this frequency is about impossible but for this example let's assume it is possible.
The short 1/4 wave may have a beamwidth that is 30 degrees wide and aimed at the horizon. The Sigma may have a beamwidth 15 degrees wide aimed at the horizon. The closer two stations are together, the less important aiming the beamwidth becomes. Think of a beam of light emitting from one antenna to another. If we compress the light beam into a narrow 360 degree beam, it will reach out further in all directions.
At the same time it will only place a small bright spot of light on the antenna that is very close. If the beamwidth of light were many degrees wider, we could illuminate a larger section on the close antenna but there will not be any visible light in the distance. Lighting up a bigger section of the closer antenna is likely to show more total energy locally then one small bright spot.
This is a very rudimentary analogy and over simplifies several things including how ground reflections affect RF in terms of beamwidth and take off angle. RF at HF frequencies cannot be controlled or focused nearly as effectively as light either, but if you follow the concept you can see how it applies to targeting different locations with an antennas beamwidth and take off angle.
Targeting skywave DX requires different radiation angles then line of sight. At first one might think a high gain vertical with low angle radiation on the horizon would be poor in DX. The good news is most antennas of this type cannot avoid producing secondary lobes above the horizon that are very useful for skywave DX.
I wonder if Im scratching the same side of my head as you are. It sounded to me like he was saying both. that my low angel antenna won't hit a higher angel antenna as good close in but my low angel antenna will hit a high angel antenna real good further out but I don't see the diffrence. If his is a high angel antenna and mine is low then he isn't going to ever hear me as well as a high angel antenna at any distance? I still think the lowest angel antenna will do the best close in or far out if its up high enough to get over everything in the way because it concentrates the power more but if it isn't then a higher angel antenna is probably better when there low to the ground.
Let's not twist my words around. If you want it packaged up simply, antennas with low angle radiation have increased coverage that may come at the very slight expense of local signal strength. Since the loss in local signal is almost never noticed, I would go for the low angle antenna in almost every case.