Just looking for anyones thought on how high a cb base antenna really needs to be or is height really might?I talked to a tech at maco back when they were maco and was told 40 ft is plenty high enough for a antenna, so what do you all think, Thanks
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Antenna height
- Thread starter albino128
- Start date
http://signalengineering.com/ultimate/angle_of_radiation.html
Explains about height and how it will affect your signal.
Explains about height and how it will affect your signal.
Albino128
my pine trees are about 65 to 70 feet in the air.My antron99 sits only 5 to 7 ft lower
everybody in my neiborhood says I bleed on them,whats that telling you (higher is better).I use to live up in the coner of the buck 10 my, brothers maco was atleast 100 ft off the ground ,just alone we talked to cleveland from andover ohio barefoot
my pine trees are about 65 to 70 feet in the air.My antron99 sits only 5 to 7 ft lower
everybody in my neiborhood says I bleed on them,whats that telling you (higher is better).I use to live up in the coner of the buck 10 my, brothers maco was atleast 100 ft off the ground ,just alone we talked to cleveland from andover ohio barefoot
i would at least try to get into the second wavelength, which is like 36' high. any antenna at 40' will usually get the job done.
There are sort of two parts to that question. One part is that the height above ground affects the amount of reactance between the antenna and ground. That means that tuning the antenna can change if raised or lowered an appreciable amount.
Another part is that height affects the radiation pattern. The horizon gets further away the higher the antenna is, so it can 'see' further in a straight line, before any 'skip', sort of. Not too important at HF really, but it is important at VHF/UHF. So, the higher the better to some ridiculous point.
So, how low can an antenna be? The lowest for most vertical or groundplane, or non-horizontal and directional antennas (beams) is -at- ground level, does no good at all below ground level. Those directional antennas have sort of a catch, cuz they could be 'vertical arrays' such as broadcast stations have. Ground level and directional, sort of harder to turn though.
Best all around height for a typical vertical groundplane type thingy is as high as you can get it.
The only kind of interference that height can 'cure' is 'over-load', since it's further away from the affected device(s). Won't 'cure' spurious or harmonic type interference since antennas don't 'produce' any signal, they just radiate what's fed to them. They can attenuate or increase the signal, just can't make any of their own.
- 'Doc
Another part is that height affects the radiation pattern. The horizon gets further away the higher the antenna is, so it can 'see' further in a straight line, before any 'skip', sort of. Not too important at HF really, but it is important at VHF/UHF. So, the higher the better to some ridiculous point.
So, how low can an antenna be? The lowest for most vertical or groundplane, or non-horizontal and directional antennas (beams) is -at- ground level, does no good at all below ground level. Those directional antennas have sort of a catch, cuz they could be 'vertical arrays' such as broadcast stations have. Ground level and directional, sort of harder to turn though.
Best all around height for a typical vertical groundplane type thingy is as high as you can get it.
The only kind of interference that height can 'cure' is 'over-load', since it's further away from the affected device(s). Won't 'cure' spurious or harmonic type interference since antennas don't 'produce' any signal, they just radiate what's fed to them. They can attenuate or increase the signal, just can't make any of their own.
- 'Doc
it depends on your local topography / ground conductivity and where you want to talk to,
in my area i had the best results from antennas mounted in a field at 73ft or about 2 wavelengths to the feedpoint, if i could have gone higher i would have,
some antennas work well even when mounted low and some don't,
for local talk the higher you get the antenna above its surroundings and ground the further you can talk in my experience,
for talkin skip the best height is the height that gives the takeoff angle that allows you to skip to where you want to talk,
the best height constantly changes with the conditions of the ionosphere.
in my area i had the best results from antennas mounted in a field at 73ft or about 2 wavelengths to the feedpoint, if i could have gone higher i would have,
some antennas work well even when mounted low and some don't,
for local talk the higher you get the antenna above its surroundings and ground the further you can talk in my experience,
for talkin skip the best height is the height that gives the takeoff angle that allows you to skip to where you want to talk,
the best height constantly changes with the conditions of the ionosphere.
"the best height constantly changes with the conditions of the ionosphere."
in direct correlation to the height and ionization levels of the F1 & F2 layers
which can range typically anywhere from 90 - 250 miles above the earth.
See: The Ionosphere, F1 & F2.
http://www.firecommunications.com/propflash.htm
in direct correlation to the height and ionization levels of the F1 & F2 layers
which can range typically anywhere from 90 - 250 miles above the earth.
See: The Ionosphere, F1 & F2.
http://www.firecommunications.com/propflash.htm
Basically Higher is Better
But
There comes a point we can not keep it up high safely
or antenna height restrictions in your area come into play
Mine are at 52 or 54 ft at the base of my 11 meter antenna
and it works great
Location has a lot to do with it
get your antenna high enough at least so it gets a clear shot to transmit
is best to get it a full wave length or higher
But
There comes a point we can not keep it up high safely
or antenna height restrictions in your area come into play
Mine are at 52 or 54 ft at the base of my 11 meter antenna
and it works great
Location has a lot to do with it
get your antenna high enough at least so it gets a clear shot to transmit
is best to get it a full wave length or higher
Hight is good for the groundwave, after 1 wavelength above ground the radiation pattern will be good for DX, depending your surroundings, houses etc wich might be higher.
My vertical is 11 meters above ground, flat terrain, and working the world on 15 - 10 meters with it.
It's an Imax 2000 with ground plane, added ground plane wires for 15 and 12.
For the groundwave, gaining 1 S point needs an doubling of your antenna height.
For DX, selext an vertical that has the lowest angle of radiation.
Worked the USA 100 watts with the imax on 10 meters yesterday
Cor
My vertical is 11 meters above ground, flat terrain, and working the world on 15 - 10 meters with it.
It's an Imax 2000 with ground plane, added ground plane wires for 15 and 12.
For the groundwave, gaining 1 S point needs an doubling of your antenna height.
For DX, selext an vertical that has the lowest angle of radiation.
Worked the USA 100 watts with the imax on 10 meters yesterday
Cor
Glad you could Robert
Location , Do you live on a hill top with clearance for miles and miles ?
darn shit pipes will work then How low can you go ? Well , have a buddy who has a antenna farm , all his antenna's are low (maybe 20 ft push ups and shit pipes) I can here this dude 40 miles away on a old Salute or Alpha.
LOCATION LOCATION LOCATION........I've always shot for the stars myself , only to lose a few good ground planes over the years. (Damn I loved to look at those babies from a distance
) Albino ? Hows that radio of yours tuned ? What kind of feedline are you using. 99s are known for there bleed but can help to use the best feedline you can get your hands on , a good clean tuned radio would be a plus as well , good ground , because you sound like your plenty high enough.
Nowadays (again depending on location) I like 40 ft with good feedline and ground if at all possible. (clean tuned radio helps too
) 
A good rule of thumb for antenna height is that the base of the antenna should be at least one full wavelength above ground. For CB frequencies that would be 11 meters or approx 36 feet. for longer skip jumps 80 feet is a good choice.
- 399
- 399
Something else to remember is that there is no definitive, absolute, never 'bad', and if you can't get it "don't bother" antenna height. There are particular characteristics about some antenna heights that are 'generally' good. Those deal with how an antenna behaves at a particular height, how it 'relates' to the dirt under it. After something like 1/4 wave above ground, things sort of 'even out' sort of, some variables aren't as variable anymore. That doesn't mean anything about what the thing 'hears', just how it 'behaves' electrically.
Almost anything is better than nothing, and there ain't no such thing as a free lunch. That's about as 'general' as you can get...
- 'Doc
Almost anything is better than nothing, and there ain't no such thing as a free lunch. That's about as 'general' as you can get...
- 'Doc
Almost anything is better than nothing, and there ain't no such thing as a free lunch. That's about as 'general' as you can get...
- 'Doc
Doc Rocks !!
- 'Doc
Doc Rocks !!