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Antenna Simulation Project - RF Cafe Forums

RF Cafe Forums closed its virtual doors in 2010 mainly due to other social media platforms dominating public commenting venues. RF Cafe Forums began sometime around August of 2003 and was quite well-attended for many years. By 2010, Facebook and Twitter were overwhelmingly dominating online personal interaction, and RF Cafe Forums activity dropped off precipitously. Regardless, there are still lots of great posts in the archive that ware worth looking at. Below are the old forum threads, including responses to the original posts.

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htgr2001
 Post subject: Antenna Simulation Project
Posted: Sun Apr 12, 2009 2:27 pm 
 
Lieutenant

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:

Image

Very simplistic model of a 5 element Yagi Antenna (no boom)

Image Image

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.


 
   
 
nubbage
 Post subject: Re: Antenna Simulation Project
Posted: Mon Apr 27, 2009 7:42 am 
 
General
User avatar

Joined: Fri Feb 17, 2006 12:07 pm

Posts: 236

Location: London UK

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

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nubbage
 Post subject: Re: Antenna Simulation Project
Posted: Mon Apr 27, 2009 7:46 am 
 
General
User avatar

Joined: Fri Feb 17, 2006 12:07 pm

Posts: 236

Location: London UK

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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