[aprssig] RFID bigger coil

[Wes Johnston, AI4PX]

Why not rectangular, say 4" x 30" to cover the threshold of a door?

Wes

On Thu, Feb 25, 2010 at 12:26, Robert Bruninga <bruninga at usna.edu> wrote:

> Biggest RFID Coil yet.
>
> Today,  I doubled the size again to a 23" square coil and it
> also
> works well.  Resonance was not as peaked, but its vertical
> detection range was
> still about 12" and the outside-the-coil range was about 5"
> giving an overall
> HotSpot of nearly 33" across.  THe advantage of this larger coil
> is that a moving
> tag is in the coil longer and therefore can be detected at a
> faster speed.
> Even throwing a card across the coil Frysbee style would always
> detect.
>
> Shucks, in two more doublings of the size, it will be big enough
> (3' by 7') that might surround a door!  I cannot imagine that it
> could possibly work because the field will be so weak... But who
> knows..
>
> Bob, WB4APR
>
>
> _______________________________________________
> aprssig mailing list
> aprssig at tapr.org
> https://www.tapr.org/cgi-bin/mailman/listinfo/aprssig
>



-- 
Wes
---
God help those who do not help themselves.
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://www.tapr.org/pipermail/aprssig/attachments/20100225/4ce5e47b/attachment.htm>