Re: [amsat-bb] Satellite Antenna Modeling

[Paul Yeager <w4ski@xxxxxxxx>]

Keith:

   Does ground conductivity matter to such an antenna, especially if it 
includes a reflector and is pointed at the sky?

  I use a helix for UHF uplink to AO-40 (at least, I used to, and hope to 
again).  I homebrewed mine based on one in the ARRL Antenna Book.   I never 
modeled it, but it seems to work just fine!

My helix has an almost 2 foot square reflector, which is actually a screen 
door protector from my local home improvement store.  It is expanded metal 
"grid" material with a extruded aluminum frame.

73,

Paul W4SKI

At 11:50 PM 2/2/04 +0000, Keith O'Brien wrote:
>Using the antenna modeling program EZNEC to model a 435 MHz RHCP Helix for 
>satellite use, I have a question someone might be able to help me with. 
>With in the program you are able to pick different grounds from which your 
>antenna will operate above. Searching the internet I was able to acquire 
>from the FCC site, that this portion of Florida has a ground conductivity 
>of 4 millimhos per meter. EZNEC is looking for the ground conductivity in 
>Siemens per meter. I have searched and can't seem to come up a answer to 
>my question.  How does millimhos relate to Siemens? Are they one in the 
>same? Is 4 millimhos the same as .004 Siemens? Anyone ?
>
>By the way, does anyone know of a site that might already have antenna 
>modeling files available?  I'm more interested in experimenting with 
>antenna designs then taking the time to build them up within the program. 
>Not really wanting to try to reinvent the wheel, if its already available.
>
>Thanks for your help.. Keith
>
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