I realize I am somewhat putting carts before horses (they can still push them, right?), but I have a question on Yagi antennas. I am, if I have the time today, getting my 6dBi omni antenna up into my attic to test placement. Just a quick test from my bathroom roughly below where I am planning to place the antenna I am able to hit the repeater I am looking to use. No way to test Tx/Rx from my brother-in-law's house which is vaguely in the same direction (more below). The Rx back from the repeater was weak and moving the antenna around in the bathroom a little changed from weak to nothing, to slightly better weak. I'd imagine getting an extra 5-7' of height by having it up in the attic should help a fair amount. Also not having a low E window, or tile, with concrete backer, insulation and then finally the plywood and siding will help even more.
But I am letting my anxiety leak out that I'll be able to hit the repeater, but it'll still be too weak to be very usable and just plotting and scheme ways to improve my situation. I assume since it is over the horizon, by a lot, I've got a 100ft high ridge, about 1.5 miles from my house between me and the repeater, then about another 14-17 miles to the tower, which is sitting at probably only 50-80ft higher altitude at the top of the tower than the ridge line near my house is, that the more altitude I can get on my antenna the better. So if attic placement doesn't help, getting it mounted to the peak of the roof on a 3-4' j-pole mount, getting another 5-6' above how high I can get it in the attic should help even more (plus no losses from the attic structure, but it is just plywood sheathing and vinyl siding it has to go through since the repeater is out a gable wall).
Now, that said, I'd like to avoid roof mounting if I can. My wife won't be thrilled and its frankly a lot more work then needing to deal with grounding, proper mounting/securing, etc.
So my thoughts turned to install a yagi and using an antenna switcher. That seems reasonable enough.
However, I am also trying to hit my brother-in-laws. He is over that same ridge, but a total of about 4 miles away. Not on the same path. Doing some quick and dirty math his location and the repeater appear to form a scalene triangle with the angle between the repeater and him at my location being somewhere between 37-41 degrees. That seems like a fairly wide angle to get good gain on both locations from a Yagi. At least to get more gain than the supposed 6dBi I am getting on the omni antenna I am installing now. Is that too much horizontal dispersion? It seems like the higher the gain, the narrower the horizontal beam width would be on a Yagi and from what little I can dig up in poking, I'd see something like a 3dBi horizontal beam width with a 7dBi 3 element Yagi. So I'd likely see even lower gain for those two points if I pointed it directly between them, than I would be with a 6dBi ombi. And a 5 or 7 element Yagi wouldn't really help that, as it would just narrow the beam width further.
I'd of course prefer not to be in a situation where I've got a Yagi pointed at each spot PLUS the omni and needing to switch between all 3 depending on what I want to be doing (if I do, I do, just of course trying to avoid that). I might be borrowing trouble for another day, but just trying to get a better understanding of Yagi radiation pattern. Is it that as the gain goes up, the beam pattern narrows? or is it reducing radiation pattern of the direction it is pointed, so the lobs are reduced and that is where the gain is coming from? For example, could an 11dBi yagi actually produce 7 or 8dBi of gain on a couple points ~40 degrees spread? Or am I tilting at windmills on this on trying to get a Yagi to hit two points, too broadly spread?
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lazarus1024
I realize I am somewhat putting carts before horses (they can still push them, right?), but I have a question on Yagi antennas. I am, if I have the time today, getting my 6dBi omni antenna up into my attic to test placement. Just a quick test from my bathroom roughly below where I am planning to place the antenna I am able to hit the repeater I am looking to use. No way to test Tx/Rx from my brother-in-law's house which is vaguely in the same direction (more below). The Rx back from the repeater was weak and moving the antenna around in the bathroom a little changed from weak to nothing, to slightly better weak. I'd imagine getting an extra 5-7' of height by having it up in the attic should help a fair amount. Also not having a low E window, or tile, with concrete backer, insulation and then finally the plywood and siding will help even more.
But I am letting my anxiety leak out that I'll be able to hit the repeater, but it'll still be too weak to be very usable and just plotting and scheme ways to improve my situation. I assume since it is over the horizon, by a lot, I've got a 100ft high ridge, about 1.5 miles from my house between me and the repeater, then about another 14-17 miles to the tower, which is sitting at probably only 50-80ft higher altitude at the top of the tower than the ridge line near my house is, that the more altitude I can get on my antenna the better. So if attic placement doesn't help, getting it mounted to the peak of the roof on a 3-4' j-pole mount, getting another 5-6' above how high I can get it in the attic should help even more (plus no losses from the attic structure, but it is just plywood sheathing and vinyl siding it has to go through since the repeater is out a gable wall).
Now, that said, I'd like to avoid roof mounting if I can. My wife won't be thrilled and its frankly a lot more work then needing to deal with grounding, proper mounting/securing, etc.
So my thoughts turned to install a yagi and using an antenna switcher. That seems reasonable enough.
However, I am also trying to hit my brother-in-laws. He is over that same ridge, but a total of about 4 miles away. Not on the same path. Doing some quick and dirty math his location and the repeater appear to form a scalene triangle with the angle between the repeater and him at my location being somewhere between 37-41 degrees. That seems like a fairly wide angle to get good gain on both locations from a Yagi. At least to get more gain than the supposed 6dBi I am getting on the omni antenna I am installing now. Is that too much horizontal dispersion? It seems like the higher the gain, the narrower the horizontal beam width would be on a Yagi and from what little I can dig up in poking, I'd see something like a 3dBi horizontal beam width with a 7dBi 3 element Yagi. So I'd likely see even lower gain for those two points if I pointed it directly between them, than I would be with a 6dBi ombi. And a 5 or 7 element Yagi wouldn't really help that, as it would just narrow the beam width further.
I'd of course prefer not to be in a situation where I've got a Yagi pointed at each spot PLUS the omni and needing to switch between all 3 depending on what I want to be doing (if I do, I do, just of course trying to avoid that). I might be borrowing trouble for another day, but just trying to get a better understanding of Yagi radiation pattern. Is it that as the gain goes up, the beam pattern narrows? or is it reducing radiation pattern of the direction it is pointed, so the lobs are reduced and that is where the gain is coming from? For example, could an 11dBi yagi actually produce 7 or 8dBi of gain on a couple points ~40 degrees spread? Or am I tilting at windmills on this on trying to get a Yagi to hit two points, too broadly spread?
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