I can’t remember if I read about it somewhere here in these forums or on a FB group post, but someone was mentioning about, for example, a 6db gain mobile antenna. The way that it accomplishes that gain is by shallowing down that take off angle into something more narrow of disc shaped and really concentrating that radiation to something like a degree or two. And that’s great for ERP increases, but a mound of solid dirt in front of you at the foot of an incline on the roadway is just going to absorb it if you’re running 5 watts or 50. And in this scenario, you’re just beaming that signal nearly horizontally right into it. So if there was a receiving vehicle a mile ahead and already on top of that increased elevation, he may not hear anything at all.
But now suppose you have a 3bd gain antenna which is a bit more Omni direction in the vertical axis, perhaps shooting as high as 10-15 degrees. It’s lower ERP, but would be casting signal into more useful directions in realistic terrain environments.
When you first get into mobile line of sight radio-ing, one of the first things that you become more keen on is how the terrain lays out ahead of you as you’re driving. You see those high points, and low dips and you just know when you’re optimal for shooting out a nice signal and when you’re likely to get into a dead spot down in a hole. So with that being said, is a high gain vertical actually counter productive in mobile applications?
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SvenMarbles
I can’t remember if I read about it somewhere here in these forums or on a FB group post, but someone was mentioning about, for example, a 6db gain mobile antenna. The way that it accomplishes that gain is by shallowing down that take off angle into something more narrow of disc shaped and really concentrating that radiation to something like a degree or two. And that’s great for ERP increases, but a mound of solid dirt in front of you at the foot of an incline on the roadway is just going to absorb it if you’re running 5 watts or 50. And in this scenario, you’re just beaming that signal nearly horizontally right into it. So if there was a receiving vehicle a mile ahead and already on top of that increased elevation, he may not hear anything at all.
But now suppose you have a 3bd gain antenna which is a bit more Omni direction in the vertical axis, perhaps shooting as high as 10-15 degrees. It’s lower ERP, but would be casting signal into more useful directions in realistic terrain environments.
When you first get into mobile line of sight radio-ing, one of the first things that you become more keen on is how the terrain lays out ahead of you as you’re driving. You see those high points, and low dips and you just know when you’re optimal for shooting out a nice signal and when you’re likely to get into a dead spot down in a hole. So with that being said, is a high gain vertical actually counter productive in mobile applications?
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