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[TowerTalk] Re: New + Ant Ramblings

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Subject: [TowerTalk] Re: New + Ant Ramblings
From: (David & Barbara Leeson)
Date: Mon, 19 May 1997 00:03:03 -0500 (EST)
An interesting antenna to compare the new Skyhawk and the existing C3's
to is the Hy-Gain 13-el log periodic on 26' boom.  This is a very 
conservative design, and doesn't have the F/B possible with spot-
frequency Yagi-based antennas, but it also has gain in the 7.0-7.5 dBi
range (as measured roughly by comparison to HG204BA and also pattern-
width measurements, no claims of accuracy but seemed to confirm HG
measurements).  I don't know about pricing comparisons, but I've used
one of the LP's here for several years, it survived 130+ mi/h winds that
broke the #60 drive chain on the Skyneedle it was on.  Just a thought...

On a separate subject, I've been working off and on to design a no-
comprimise duoband interlaced 5 el for 10-15 and 10-20, among other
possibilities.  I've gotten to the point that I can have the exact
same performance with the duobander model that I get with the
individual single band Yagis, but it requires traps in the last director.

The idea is to have two separate "drive cells" that are R-DR-D1, with
the higher band in front of the lower band or with the lower band D1
between the higher band R-DR.  Adding 2 more directors is the hard part,
but it can be done if at least the last one is trapped.  Since the current
in the last director isn't very large, the loss of the traps isn't a
big factor.  My goal is to have, for example, a 10-15 with full SWR\
bandwidth (21-21.45 and 28-28.8 is my band of interest) and 10 dBi gain.

My experience with stacking is that any reasonable stacking wipes out
the gain of the higher band antennas because of the reflector action of
the directors of the lower band antenna(s), so tribanders are often just
as effective, or maybe even more effective, on the higher bands of the
stack.  I'd be happy to share AO files (have been so busy last few years
haven't even had time to update to NEC-Wires and WA3FET software!) with
anyone interested and willing to pick it up from here.

Another suggestion for a useful antenna is an interlaced 40-20, with the
40 elements having 20 traps rather than just loading coils.  My grad
class at Stanford is buzzing away on their term microwave projects, so
I will have more time after the end of the school year.

Meanwhile, I add my admiration as expressed by Bruce Horn for the designers
of the new antenna, but also for those at F12 and HG, all of whom are 
dancing the line between what you'd like and what you're able to pay for!

Cheers de Dave, W6NL (ex-QHS)

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