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Antenna Simulation Project - RF Cafe Forums
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htgr2001
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Post subject: Antenna Simulation Project
Posted: Sun Apr 12, 2009 2:27 pm
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Joined: Sun Apr 12, 2009
2:25 pm Posts: 1 |
Hello guys, I am not quite sure how to start
this thread; I am involved in this little project
to simulate (using a software package called FEKO)
the radiation pattern of a few antenna types under
a variety of realistic conditions. Most of
all I will be creating 3d models on the package
of a few types of antennas. To get your
curiosity going I will post a few pictures:
Very simplistic model of a 5 element Yagi Antenna
(no boom)
Radiation Patterns at 100MHz (left) and 95MHz (right)
I have used a few dimension formulas I found
online to optimize the antenna for frequencies of
95.5 MHz. Still it seems to operate better at higher
frequencies as you can see. So at the moment
where I would really appreciate your help is if
you could provide or point me towards a reliable
source of antenna dimensions.
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nubbage |
Post subject: Re: Antenna Simulation Project
Posted: Mon Apr 27, 2009 7:42 am
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General |
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Joined: Fri Feb 17, 2006
12:07 pm Posts: 236 Location: London UK
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Hi You can find full design graphs and details
in Amateur Radio publications, and be confident
they have been well-tried and tested. This is about
the only source of information in the public domain,
since manufacturers protect their designs by secrecy.
I spoofed around this when checking my own designs
and checking the Mini-NEC software. I shamelessly
did this by photo-copying a side-on photograph of
designs by a well-known European manufacturer, taking
the usual dimension for the radiator as 0.5*wavelength
minus 4%, and then scaling all dimensions. Thus
I was able to arrive at spacings and lengths of
all elements. It worked very well.
_________________ At bottom, life is all
about Sucking in and blowing out.
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nubbage |
Post subject: Re: Antenna Simulation Project
Posted: Mon Apr 27, 2009 7:46 am
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General |
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Joined: Fri Feb 17, 2006
12:07 pm Posts: 236 Location: London UK
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On another point you raised: the bandwidth of a
simple yagi, with no broad-banding of the radiator,
is only about 6%. The first parameter to suffer
degradation outside this bandwidth will be the front-to-back
ratio. Another point worth mentioning is that
you might design a yagi with a good set of radiation
pattern envelope (RPE) parameters, but the impedance
match could be awful: like a VSWR of 6:1, not good.
_________________ At bottom, life is all
about Sucking in and blowing out.
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Posted 11/12/2012
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