Topband: 160M/80M Vertical - Using a capacity hat below a trap

[George]

Rich,

The short answer should be Yes.

Our "Battle Creek Special" Vertical antenna, available as a loaner antenna, 
does that.  Usable on 40, 80 & 160 m, the vertical/inverted L antenna is 
trapped for 40 m, then at 48' for 80 m.  We simply added a wire for 
capacitive top loading wire as part of the guy just below the 80 m trap to 
resonate it on 3.5 mhz.  Works FB.

To finish the BCS, a horizontal wire is added above the 80 m trap to 
complete an "Inverted L" on 160 m.

Our BCS loaners have been in use for over 30 years and put out a respectable 
signal on the low bands.

73  George  W8UVZ

-----Original Message----- 
From: rich kennedy via Topband
Sent: Wednesday, October 01, 2014 8:15 AM
To: topband at contesting.com
Subject: Topband: 160M/80M Vertical - Using a capacity hat below a trap

I’m finalizing design for my 160M/80M shortened wire tree-mounted
vertical.  An Unadilla 80M trap will be
placed approx. 65’ feet above the feedpoint; above the trap is another 20 
feet
with a small cap hat.  An autotuner
handles the Z matching for the anticipated 500 watts on both bands.

QUESTION: Can one install a capacitive hat directly below
the 80M trap to help shorten the length of the 80M section?  For example, 
shortening the 80M radiator to
60’ (from 65’) and making up ‘the difference’ with a capacity hat?  Any 
downside?

NOTE: Please omit suggestions about using a larger hat on
160M (sloping wires, etc.) – I know that it is much more desirable, but that 
is
just not feasible here at K3VAT.

Thanks, 73, Rich, K3VAT
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