[Towertalk] split feed antennas
Guy Olinger, K2AV
k2av@contesting.com
Sat, 19 Oct 2002 12:42:38 -0400
Unfortunately there is no kw level 96 ohm coax. What you need is the
alternate runs transformer formula, to match each incoming line to 100
ohms zero reactance. The formula gives you low z, run of hi z coax,
run of lo z coax, hi z to match a complex impedance to another. Two
100 ohm no X loads into a T is a match to 50 ohms. If you don't get
the two lines matched to 100 ohm no X, the power division becomes
uncertain.
Unfortunately 100 ohms target is the extreme high end of the device's
range using 75 ohm coax as hi coax.
Our experience with stuff like this at field day was that the dual fed
devices had a narrower SWR range than the antenna's by themselves.
Also, in case not already obvious, they are a single band frequency
dependent solution.
Transformer driven devices, like the commercially available
stackmatch, do better.
73, Guy.
----- Original Message -----
From: "S Johns" <petvet@adelphia.net>
To: "Towertalk" <towertalk@contesting.com>
Sent: Saturday, October 19, 2002 10:12 AM
Subject: [Towertalk] split feed antennas
> I am looking for experienced suggestions regarding the better
methods to
> transform a feedline's complex impedance in the shack (to keep the
Alpha
> 87A happy) when split feeding dissimilar antennas/feedlines for
crude
> power divide through a T connector (ie. simultaneously feeding a 3
> element 40 meter yagi and a 40 meter inverted V).
>
> E-mail directly petvet@velocity.net
>
> I'll create a summary for the list therafter.
>
> 73, Scott W3TX
>
>
> _______________________________________________
> AN Wireless Self Supporting Towers at discounted prices,
> See http://www.mscomputer.com
>
> Wireless Weather Stations now $349.95. Call Toll Free,
> 888-333-9041 for additional information.
> _______________________________________________
> Towertalk mailing list
> Towertalk@contesting.com
> http://lists.contesting.com/mailman/listinfo/towertalk
>