[MLB-WIRELESS] Omni antenna's

[Fulton, Darren J]

This is what I noticed:
---------
Drew, I'm not an expert but a quick comparison between their coax collinear
and the one it's based on by Mike Collis shows a few unexplained
differences:

1) The description of the 1/4 wave whip assembly gives the impression that
the whip should be the same length as the 1/4 wave coax segment below it.
The Collis design says that while the length of the 1/4 wave coax segment is
shortened by the velocity facter, the whip should be a true 1/4 wave (not
corrected) long.

2) Like the example above the decoupling sleeve in the Collis design is a
true 1/4 wave long, the G.net guys just label this 1/4 wavelength and lead
the reader to assume it's 1/4 wave velocity corrected.

3) The decoupling sleeve seems to be connected to the wrong spot on the
feedline. The Collis design (backed up by the ARRL Antenna book 17ed p.26-9)
joins the sleeve 1/4 wave down from the point at which the feedline joins
the 1st element. The G.net design joins it 1/4 wave up from the N connector
but then contradicts this in their diagram.

Darren
---------
> -----Original Message-----
> From: David Arnold [mailto:arnold at dstc.monash.edu.au]
> Sent: Wednesday, 3 April 2002 10:12 AM
> To: melbwireless at wireless.org.au
> Subject: Re: [MLB-WIRELESS] Omni antenna's 
> 
> 
> -->"Darren" == Fulton, Darren J 
> <Darren.Fulton at team.telstra.com> writes:
> 
>   Darren> There are a few errors with that design. Drew said he had
>   Darren> mentioned this to one of the designers a while back but they
>   Darren> still haven't corrected the web page yet.
> 
> Drew?  care to summarise the problems?  i'm keen to build an omni ...

To unsubscribe: send mail to majordomo at wireless.org.au
with "unsubscribe melbwireless" in the body of the message