is given that this graph is not useful above 2 meters, oh well.
--John
--- On Thu, 8/27/09, Burt Lang b...@gorum.ca wrote:
From: Burt Lang b...@gorum.ca
Subject: Re: Fw: Re: [Repeater-Builder] 2 meter folded dipoles for multi bay
design information needed
To: Repeater-Builder@yahoogroups.com
Date
The only possible problem with this design is feeding a balanced antenna (the
folded dipole) with unbalanced feed. This will lead to some amount of feedline
radiation; yes, it is using coax which is shielded but the unwanted RF current
in this situation flows on the _outside_ of the coax, on
Yes, it does depend on the antenna, to wit, diameter of the elements spacing
between the elements. Can be made lower or higher than 300 ohms. There's
nothing sacred about 300 ohm Z. It was a match for 300 ohm TV twinlead in
the older daze.
--John
--- On Thu, 8/27/09, Chuck Kelsey
Actually 300 ohms is special. It is the impedance of a folded dipole
with equal diameter elements, the end result of bending a single piece
of tubing into a U. And the impedance is not affected by the spacing
between the elements (according to the handbook theory).
Burt VE2BMQ
John Sehring
Anyone built this non-folded dipole array project? It uses 3/4 copper pipe,
PVC stand offs and 75 ohm coax for the phasing harness...
http://forums.radioreference.com/attachments/antennas-coax-forum/16043d1213582941-4-bay-vhf-dipole-array-project-low-cost-high-performance-vhf-dipole-array.pdf
John Sehring wrote:
The only possible problem with this design is feeding a balanced antenna
(the folded dipole) with unbalanced feed. This will lead to some amount
of feedline radiation; yes, it is using coax which is shielded but the
unwanted RF current in this situation flows on
Hi AJ,
I am thinking of building one element for a go kit antenna for temporary
deployment on a existing mast or a piece of conduit.
AJ aj.grant...@... wrote:
Anyone built this non-folded dipole array project? It uses 3/4 copper pipe,
PVC stand offs and 75 ohm coax for the phasing
One comment if I may, I noticed the UHF version shown had the dipoles spaced
around the mast instead of directly one above the other. Spacing around the
mast like that at this frequency gives very bad vertical and horizontal
patterns and much reduced gain. That's because the horizontal
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