Angle of Radiation using a quad whats the best height for 27MHz? 1 wavelenght or better? comments???
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Best height for a Quad?
- Thread starter gunsmoke241
- Start date
It all depends on where you want to talk to and the height of the ionosphere that particular moment. What works at 24 feet today may not work tomorrow. Your height above ground changes your take-off angle of your signal. This angle combined with the height of the ionosphere will determine where your signal will land. Since the ionosphere's height is always changing, and your take-off angle can change based on the height of your antenna above the ground, you can beam your signal almost anywhere you want!
Those who are serious into DX will have, as a minimum, a crank-up tower in order to change the height of their antenna to meet their communications needs. Others will have stacks of antennas or a motorized tower.
For a fixed height, somewhere between 18' and 36' and you get what you get. Today may be awesome, and tomorrow your signal lands in the middle of the Atlantic.
http://www.qsl.net/ki0eg/propagation/propprimer.html
Those who are serious into DX will have, as a minimum, a crank-up tower in order to change the height of their antenna to meet their communications needs. Others will have stacks of antennas or a motorized tower.
For a fixed height, somewhere between 18' and 36' and you get what you get. Today may be awesome, and tomorrow your signal lands in the middle of the Atlantic.
http://www.qsl.net/ki0eg/propagation/propprimer.html
There is no particular "best" height as such. There is a sort of minimum height, that being high enough that you don't 'clothes-line' yourself or get many bumps from hitting the thing. (There's also a maximum height ,60 feet, but I won't mention that. Sshhh!)
To paraphrase 'M.C.' a little, the 'best' height is variable with propagation and changes fairly often. So, in general, the 'best' height it the highest you can get. It really isn't ~that~ critical. If you really want too, motorize the tower so that you can remotely change height and look for that 'best' height. (Please take pictures!)
- 'Doc
To paraphrase 'M.C.' a little, the 'best' height is variable with propagation and changes fairly often. So, in general, the 'best' height it the highest you can get. It really isn't ~that~ critical. If you really want too, motorize the tower so that you can remotely change height and look for that 'best' height. (Please take pictures!)
- 'Doc
W5LZ
so this a max height of 60 feet ..I see ...so 90 feet or more would be to much then? I understand that I need to be least at 36-40 feet min. for 27 Mhz...no more than 60 ft? I have seen guys put their antennas at 100 feet or more and we are talking about beams.
so this a max height of 60 feet ..I see ...so 90 feet or more would be to much then? I understand that I need to be least at 36-40 feet min. for 27 Mhz...no more than 60 ft? I have seen guys put their antennas at 100 feet or more and we are talking about beams.
My PDL-2 instructions say to put it at least 36ft to boom with higher better if leagal and it is a quad.
Roger
Roger
For local communications, the higher the better. Its just like standing on top of a high hill or tall building, the higher you are, the farther you see......all the way to the horizon.
These rules change when you skip your signals beyond the horizon. Then height above ground and the height of the appropriate ionosphere layer come into play.
A minimum of a 1/2 wave is where you start. Most manufacturers will say to get your antenna one wave length above the ground.
The FCC rules state that CB antennas can be no higher than 60' from the ground or 20' above a structure. I've always read the "structure" rule as being 20' over a 'x' story building. Lets say the local police department is in a 4-story building that is already at 60' from the ground. The rules state you can be no more than 20' over the building. Some people say that you can't be any higher than ANY building. This is not how I interpret the rules......YMMV. Ham radio dudes get to go to 200'!
So, if you want to be legal, land somewhere between 18' and 60'. Just remember, when it comes to skip, the highest elevation is not always the best elevation!
These rules change when you skip your signals beyond the horizon. Then height above ground and the height of the appropriate ionosphere layer come into play.
A minimum of a 1/2 wave is where you start. Most manufacturers will say to get your antenna one wave length above the ground.
The FCC rules state that CB antennas can be no higher than 60' from the ground or 20' above a structure. I've always read the "structure" rule as being 20' over a 'x' story building. Lets say the local police department is in a 4-story building that is already at 60' from the ground. The rules state you can be no more than 20' over the building. Some people say that you can't be any higher than ANY building. This is not how I interpret the rules......YMMV. Ham radio dudes get to go to 200'!
So, if you want to be legal, land somewhere between 18' and 60'. Just remember, when it comes to skip, the highest elevation is not always the best elevation!
all good comments and food for thought ....my primary is to talk skip ...
Master Chief said "when it comes to skip, the highest elevation is not always the best elevation!"
Thanks
Master Chief said "when it comes to skip, the highest elevation is not always the best elevation!"
Thanks
As a general rule the higher the better. If you have the ability to change that height then it becomes a matter of figuring out the exact height versus take off angle etc but for those of us who must mount our beams at a fixed height you cannot go wrong with the higher the better way of thinking.
What does this mean? Define "simple operations".Marconi said:
Many years ago I stopped by a ham's house who had a few towers on his site. I looked on in awe as he showed them to me. I questioned him as to why he had "motorized towers". He taught me about "take-off angles".
I was only 16 so the "theory" didn't make any sense so we went inside for a hands on lesson. First he raised the tower all the way up to 72'. Then he pointed the beams east. He said to listen as he flipped the switch to slowly bring the tower down. All of a sudden we could hear stations in Europe and Russia. As the antennas continued to come down, those signals faded away. Then we heard the east coast come in......then fade away. He then told me it was like bouncing balls off a pool table bumper.....change the angle and you change where the ball goes. As the antennas came down, the take-off angle changed and so did the signals we were receiving.
I'd say this about kills the notion that this is "theory" only.
Is it "simple" to flip a switch and use your ears to find the stations you are looking for? YES......but expensive! Is it "simple" to run outside and crank your tower up and down manually? NO.
I like a full wave from the ground when a variable height is not possible. You can be too high!
Master Chief said:
agrees and get the bottom of the elements 36 feet or higher. not just the boom. on beem bellow that and you are loosing gain.
That's why you see some big gun DX'ers with multiple beams for the same band on the same tower but at differant heights. They can run them phased or separately to take advantage of the differant take off angle offered by the differant heights. It can often make the differance between working a station or not.