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Old August 7th 07, 06:00 PM posted to rec.radio.amateur.antenna
Dave Platt Dave Platt is offline
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First recorded activity by RadioBanter: Jul 2006
Posts: 464
Default Question, Colinear design Error?

In article ,
amdx wrote:

According to that link, the loops are 10mm in diameter, or 10*pi mm
around.

Thanks, Dave
So 10mm*pi is equal to about 1/4 wavelength at 2.437Ghz. I have
spent
about twenty minutes with google and I don't find any info saying that is
the proper
length to phase the sections. What do you think?


There are no doubt multiple ways to construct such an antenna. A
simple approach would be to use halfwave-long vertical radiating
sections, and shorted quarter-wavelength stubs (sticking out to the
side, or curled into a near-circular shape) as phasing sections. This
would result in "stacked" half-wave radiators. The "Super J-pole"
uses this approach.

Another approach for collinears is to use 1/2-wave or 5/8-wave
radiating sections, and lumped inductors as phasing sections. An
example of this is the Hustler G7-144 (three stacked 5/8 radiators,
with lumped inductors between them).

I haven't gone over the design that you posted in detail, but it
wouldn't surprise me greatly if the main radiating sections were
around 5/8 wavelength, and the phasing loops have enough inductance to
create the appropriate phase relationships. Since the phasing
sections are inductive loops rather than shorted transmission lines,
one would not necessarily expect the "radiating section length, plus
total length of wire in the phasing section" to add up to precisely 1
wavelength.

--
Dave Platt AE6EO
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