tomerbr schrieb:

thank you for the quick answer, however this is not true that any
resonant of the 1/4 wave length will give the same performance like the
normal 1/4 wave length antenna because for longer antennas the current
that runs through the antenna will start from the 1/4 wavelength of the
antenna and will go up as well as down with an opposite phase thus
decreasing the total current of the antenna.

If you can think of another reason way they build such antennas I will
be happy to know

Thanks again
Tomer


You must not compare pure radiated power to performance/ gain.
A 1/4 wave allways needs some ground or radials to perform reasonably
good by going 80% of the radiated power to mars as of high angle
radiation. This is somewhat useful in areas with high buildings with the
repeaters on top surrounding your place but not in rural areas.
A 1/2 wave vertical is much less affected by surrounding things (at last
your own body) within a 1/4 wave distance of the antenna and a 3/4
antenna has much lower radiation angle than the others. So real
performance is a very complex thing.
Those theoretical antennas in outer space vacuum are not really
comparable to the different conditions a cell-phone antenna has to work.

But... If you are so well educated why do you ask such 'simple' things
in a cb-group?
Even most radio-amateurs could not answer your question.
You may buy that ARRL Antenna Handbook for further information on
antennas of all kind.
Also you may use an antenna simulation program like EZnec to see how
*real* antennas perform.

regards

A 1/4 wave has a high angle of radiation.

If you look closely at a cellular antenna, it's two 1/4 waves
with a phasing coil between them. As explained above, this
concentrates the power to a lower angle.

857 MHz is about 3.03 inches for a quarterwave.
I've built antennas for our local 800MHZ public service band.


Volker Tonn wrote:
tomerbr schrieb:

thank you for the quick answer, however this is not true that any
resonant of the 1/4 wave length will give the same performance like the
normal 1/4 wave length antenna because for longer antennas the current
that runs through the antenna will start from the 1/4 wavelength of the
antenna and will go up as well as down with an opposite phase thus
decreasing the total current of the antenna.

If you can think of another reason way they build such antennas I will
be happy to know

Thanks again
Tomer


You must not compare pure radiated power to performance/ gain.
A 1/4 wave allways needs some ground or radials to perform reasonably
good by going 80% of the radiated power to mars as of high angle
radiation. This is somewhat useful in areas with high buildings with the
repeaters on top surrounding your place but not in rural areas.
A 1/2 wave vertical is much less affected by surrounding things (at last
your own body) within a 1/4 wave distance of the antenna and a 3/4
antenna has much lower radiation angle than the others. So real
performance is a very complex thing.
Those theoretical antennas in outer space vacuum are not really
comparable to the different conditions a cell-phone antenna has to work.

But... If you are so well educated why do you ask such 'simple' things
in a cb-group?
Even most radio-amateurs could not answer your question.
You may buy that ARRL Antenna Handbook for further information on
antennas of all kind.
Also you may use an antenna simulation program like EZnec to see how
*real* antennas perform.

regards