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psloan
Ludicrouse Speed

join:2002-07-29
Renton, WA
reply to boomerbubba

Re: These Ducks Quack !!!

don't know much about netstubler. I just downloaded it today from www.netstumbler.com. I think it's primary use is to scan for existing wireless access points, but it was useful for me to gage my signal strength.

I used an cheap aluminum cookie sheet from safeway for my reflector. Would I gain anything from getting something thicker?

--pat


bbarrera
Premium,MVM
join:2000-10-23
Sacramento, CA
kudos:1
said by psloan:
I used an cheap aluminum cookie sheet from safeway for my reflector. Would I gain anything from getting something thicker?
No, I don't think so. The "skin effect" of microwave radiation keeps the radio waves at the surface of the metal. I remember in my college microwaves class we made a waveguide using the metal coated wrapper from a stick of Juicy Fruit gum!

I couldn't find my old electromagnetics or microwaves textbooks so a quick Googling turned this up:

The microwave currents flow in a thin surface layer of thickness about a "skin depth" from the surface. This is because electric fields cannot penetrate perfect conductors, and only penetrate real lossy conductors a little way. See the text by Kraus on Electromagnetics for a treatment if you like.

source: »www.ee.surrey.ac.uk/Personal/D.J···ves.html


bbarrera
Premium,MVM
join:2000-10-23
Sacramento, CA
kudos:1

Theory behind this antenna design

Want to understand the equations on M. Erskine's website? Mathematically inclined?

With reference to the hand drawn template on »osiris.urbanna.net/antenna_desig···emplate/ you can find the gain calculation on page 22 and the k=0.65 on page 25 in this paper:
»www.ece.mcmaster.ca/faculty/geor···_L14.pdf

I'm still searching for the half power beam width equation.

Interesting to note from the pdf of Prof Georgieva's class notes that the first reflector system was made by Hertz in 1888 (cylindrical reflector fed by a dipole). Sounds like the antenna design in this thread.
[text was edited by author 2003-02-06 15:06:36]


ikarus1
Premium
join:2002-10-23
Urbanna, VA
bbarrera;

Exceptionally nice link! Thank you very much. I downloaded her whole site and am now digging thru the math. The lady is very bright and writes a mean .pdf file.

Thanks for that nugget.

-m-
--
»osiris.urbanna.net