If the ideal lenght of an antenna is 1/4 Wave lenght then wayare the Car Cellular antennas are longer then this ?
harrogate2 wrote:
"Ralph Mowery" wrote in message
nk.net...
"tomerbr" wrote in message
groups.com...
this was a qustion from my instractor in college
As Dave said, there is no ideal length for an antenna.
The 1/4 wave antenna will have a radiation patern that sends much of
the
signal at high angles from it. Not usually good for cell phones
where they
are usually on short towers (if you call a couple of hundred feet
short).
The longer (in wavelengths) antennas tend to put the signal more to
the
horizon and not overhead. By modifying the radiation patern to
put it
more where it is needed instead of where it is not needed you get
gain in
that direction and hopefully longer range.
What an absolute load of blx.
The reason that car cellular antennae are longer than a 1/4 wavelength
is that almost all of them are centre loaded dual antennas or are 5/8
or 7/8 co-linears. The very short ones are often a little longer as
they are coupled through glass and have to be matched.
The wavelength of a signal and it's aerial have nothing to do with the
propagation pattern.
Wha? surely you jest!
73 de Mike KB3EIA -
|