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Topband: EZNEC prediction help

To: <Topband@contesting.com>
Subject: Topband: EZNEC prediction help
From: "Rick Darwicki" <n6pe@pacbell.net>
Date: Tue, 8 Feb 2005 12:52:37 -0800
List-post: <mailto:topband@contesting.com>
Can anyone familiar with EZNEC please give me a hand? The program is very 
accurate, at least when I modeled my Create 40/80 vertical the predicted 
results were right on the money with actual readings.

The problem I'm having is understanding the various readings, mainly the 3d Max 
Gain and the average gain. 

A full size 1/4 wave 160 vertical shows a 1.41 db max 3D gain and an average 
gain of -3.63. Used Mininec/medium ground.

All of the bent, twisted and short stuff that will fit on my lot calcs at a 
higher 3D max gain and less negative Average gain.  Would the gain difference 
be due to the radiation pattern? IE might one of my bent bananas be 3 db better 
than a full size antenna in some direction?  I'd take the full size any day. 

One very interesting calc was adding a top wire to the 40/80 Create ground 
plane with radials on the roof and fence. Then rerunning with as much of the 
radials as possible laying on the ground (.1 ft). The Z shot way up.

Typically I used the same ground configuration for all runs and added some 
50-200 XL to get as close to J = 0 as possible with the wires that fit on the 
lot.

Below are the various results........So, what do it all mean ???? Thanks in 
advance

Rick N6PE

      Antenna 3D Max Gain Average Gain Z ohms  Base coil 
          
      Full size 1/4 1.41 .433 = -3.64 36.65 + j2.973 0 
                
      Inverted L 33 up 85 out Elevated radials 6-14 ft hi 3.26 .583 = - 2.34 
5.676 - j3.262 136 ohms 
         
      Inverted L 33 up 80 out Elevated radials 6-14 ft high with 50% of length 
on ground 4.4 0.588 = -2.31 20.58 =+j0.23 0 
         
      Inverted L 50 up 85 out, ground mounted 2.52 0.539 = -2.68 10.34 -j.02288 
42 
         
      Inverted L 33 up 80 out, ground mounted 2.77 0.555 = -2.56 6.621 -j1.025 
180 
         
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