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Antenna radiation pattern - RF Cafe Forums
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| Mr.Whatever
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Post subject: Antenna radiation pattern
Posted: Mon Aug 14, 2006 1:07 pm
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| Captain |
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Joined: Fri Apr 07, 2006
6:10 pm
Posts: 18 |
Hello folks, I was reading this website:
http://www.qsl.net/aa3rl/ant2.html. It got me
thinking. In general, does the term "above ground"
refer to the actual Earth ground or does it refer
to an antenna's ground plane (not necessarily Earth
ground)? I was looking at the radiation patterns,
and I got curious what would happen if we actually
have a dipole antenna that is attached to a bird
(for example). Will the radiation pattern change
as the bird's flying height changes? Or will the
flying antenna maintain the same radiation pattern
as a "normal" antenna that is mounted on a mast
at the same height?
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languer |
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Post subject:
Posted: Mon Aug 14, 2006 3:57 pm
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| Captain |
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Joined: Sun May 14, 2006
8:53 pm
Posts: 17
Location: Earth
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Cool question,
Can't say I've tried it (antenna-on-a-bird
that is), but as the distance from the bird (thus
the antenna) to the ground changes so will the radiation
(for the antenna example suggested in the link).
Response of course changes with antenna types. And
if somehow you could fit the bird with a counterpoise,
then this would act as the image plane and the effects
of earth ground proximity would be lessened.
Do you have some application in mind?
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Mr.Whatever |
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Post subject:
Posted: Tue Aug 15, 2006 9:49 am
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| Captain |
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Joined: Fri Apr 07, 2006
6:10 pm
Posts: 18 |
There are several application that can benefit
from a "levitated" antenna / transmitter setup.
Now, if we change the bird to a balloon, then many
applications come to mind. I guess the main thing
that I'm trying to picture is that how to go about
predicting a signal coverage. That is why I asked
about if it changes the radiation pattern.
This came to mind because from what I read many
antenna setups are limited by the laws governing
its area of installation. I don't think anyone wants
to see a 500ft mast on their backyard. Also, materials
would be expensive. Thanks!
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languer |
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Post subject:
Posted: Tue Aug 15, 2006 4:17 pm
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| Captain |
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Joined: Sun May 14, 2006
8:53 pm
Posts: 17
Location: Earth
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That's a pretty cool application. There's a small
company I know off that works with weather balloons
and communication devices. Pretty interesting use
of technology.
As far as the antennas, using
"groundless" (not technical term) antennas (such
as a dipole) will be ok if you maintain some reasonable
distance form the ground (far-field comes to mind).
The same applies to "grounded" antennas (e.g. monopoles,
patches, any "image" antenna), the antenna requires
a close ground so you keep the "real" ground away
not to disturb the patterns (again far-field comes
to mind).
This are the premises for antennas
used in aviation, maritime, and pretty much any
other elevated type. Good distances become much
more manageable with higher frequencies.
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Mr.Whatever |
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Post subject:
Posted: Wed Aug 16, 2006 10:58 pm
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| Captain |
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Joined: Fri Apr 07, 2006
6:10 pm
Posts: 18 |
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Speaking of balloon antennas, is the company you
have in mind named Floatograph? I've seen some of
their products before and it looked very interesting.
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sag |
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Post subject
Posted: Sun Nov 26, 2006 8:21 am
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Joined: Wed Apr 05, 2006
3:34 pm
Posts: 6 |
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accually, as long as the ground is outside the 3rd
order FRESNEL zone the pattern will not change...
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Posted 11/12/2012
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