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[Towertalk] Older 4 el Cushcraft's (20-4CD,15-4CD) optimized ?

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Subject: [Towertalk] Older 4 el Cushcraft's (20-4CD,15-4CD) optimized ?
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Date: Fri, 19 Jul 2002 06:19:04 -0600
On Fri, 19 Jul 2002 06:29:32 -0400 "john naberezny" <>
> Hi Folks,
>     I would like to know if anyone has come up with a better set of 
> dimensions for these old workhorses? I am putting up all three very 
> soon. Thanks, 73, John WE2F

ALL designs are a compromise of various tradeoffs.  The CC Skywalker 
series antennas are typically around 8.5 dBi free space gain with
moderate F/B.  

Generally, GAIN and F/B do NOT peak at the same frequency / tuning.
Gain curves are rather broad and F/B patterns tend to be rather narrow.
Typically, gain at the peak F/B frequency is 1 dB below peak gain.
Exceptions are with boom lengths of 1/4 WL and 3/4 WL where 
peak gain and peak F/B come pretty close.  See Chapter 2 in the
W2PV Antenna Design Book for curves which characterize 3, 4, 
and 6L Yagi's vs. boom length.

The CC Skywalker series of 4L Yagi's are characterized by a 
noticably shorter second director.  Lengthing this director can
produce another 1 dB of gain, with *reduced* F/B.  This change
will most like require RETUNING of the Gamma Match.

The SIMPLE solution is to install the antenna as designed.
I've been VERY pleased with the performance of my CC 4L15.

Tom  N4KG

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