20 Meter Ground Plane Vertical Antenna 
Input impedance is 50 ohms!! 
Here is the one I built 
 
This is a ground plane antenna for 20 meters. Radiating element is 217.5 inches long. Bottom of the transmitting element is 60 inches off the ground. There are 8 ground radials each 145.7 inches long are all tied together 54 inches above the ground. The radiator is 1 inch aluminum pipe using 12 ga wire as the ground plane.
 
 
Here are the Far field plots for this antenna 
Great for DX
 
 
 
 
SWR plot for 800 kHz bandwidth 14.0 - 14.4 MHz 
SWR is less than 1.2 for the entire 20 Meter band
 
 
Current Field for 20 Meter Vertical Antenna
 
 
20 Meter Vertical Z plot form 14.0 through 14.4 MHz 
Antenna is matched for 50 ohm feed line.
 
 
 
Click on link below to download the antenna model file. 
Vertical20Meter8GndsRaised.maa 
 
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Marshall County Alabama Repeater Systems 
MCARS