[Antennas] WiFi Antenna

[DavidE Benedict]

demetre@fastmail.ca writes:
>Hi All,
>
>I'm looking for construction plans for a 2.4 Ghz (WiFi) vertical (non 
>directive) antenna.
>I found easy antennas to construct on the net, but all of them are 
>dicectional.
>Anyone have any plans for a high gain (9db and over) vertical ??
>I remember seeing wire antenna sometime ago, it looked like several 
>vertical diamond loops one on top of the other, but can't remember 
>where I had seen it.
>I checked the 2002 ARRL antenna book with no luck.
>
>Any Ideas ????
>
>73
>Demetre - SV1ENS


I think what you need is a "colinear" vertical. This is like the one that
you saw with diamond segments stacked upon each other. Perhaps searching
for this word "colinear" will be of help.

I made a 2M colinear vertical of copper pipe. It had 3 segments, the
bottom one being a J-Pole configuration for impedence matching. The upper
sections were isolated each by a "shorting stub", which was a compact 1/4
wave loop. I will try to represent the top part of it with typed
characters....

!
!
!
!___
 -----!
!
!
!
!___
------!
!
!
!
!  
.....etc. 
...continue down with J-Pole for the base and coax connection. 
--The stubs were about 19 inches x2 of smaller diameter soft copper, and I
formed them into a compact circles of about 6 or 7 inches diameter.

 Perhaps I could give you better details if you responded with questions,
but I got the ideas from ARRL Handbook or Antenna Book.

I did no measurements but did have good propagation with it and it seemed
to have substantial "gain" compared to the 2M Hot Shot commercial-made
antenna that I used in place of my rubber duck.

David B.
w7dbh
Oregon, USA

David B.