[TowerTalk] 40m ground plane on 15m-pattern

[Marshall Stewart]

Mike,
With EZNEC+ v.5.0.59 I modeled a 40M ground plane:
Wire #1 starts at 0,0,10 (ft) and runs to 0,0,43 (33 ft long)
Wire #2 starts at 0,0,10 (ft) and runs to 0,33,7 about 33 long and slopes
down from 10' to 7'
Wire #3 starts at 0,0,10 (ft) and runs to 0,-33,7 about 33 long and slopes
down from 10' to 7'

On 7.1 MHz EZNEC shows a clean pattern with a deep overhead null and a 25
deg take-off angle (over Real/High Accuracy earth)

On 21.1 MHz EZNEC shows an ugly pattern with an overhead null and a 45 deg
take-off angle (over Real/High Accuracy earth)

Looks like the take-off angle is much higher on 15M than on 40M.

73,
Marsh, KA5M



  

-----Original Message-----
From: TowerTalk [mailto:towertalk-bounces at contesting.com] On Behalf Of Mike
& Coreen Smith VE9AA
Sent: Sunday, May 26, 2013 6:23 AM
To: towertalk at contesting.com
Subject: [TowerTalk] 40m ground plane on 15m-pattern

Has anyone ever modeled a 40m ground plane’s pattern on 15m?

This weekend of very poor condx on 15m during CQWW WPX CW has given me extra
time to mull over what I am using on 15m.

Currently I am using a wire ground plane cut for the 40m band, base up about
10’. Antenna is wire, with 2 elevated radials, sloping down somewhat (15º
maybe). Directly fed with coax.  SWR is FB on 40 and 15m.  Hung off the top
of a Maple tree.

It works really well on 40m, but I am wondering if the pattern is distorted
or very elevated on 15m? (high angle?)

Reason I ask, is I was accidentally listening on my 160m(multiband) dipole
that is only up 10’ last night and many station were the same strength ! ! !

There’s more to it than that, but the gist of my msg is I wish to know the
elevation plot of a 15m signal on a 40m ground plane please.

Cheers/TNX, 

Mike VE9AA

Mike, Coreen & Corey
Keswick Ridge, NB

 

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