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K8KB's 20m Yagi
     
     
L1000632sm.jpg (38501 bytes) L1000619sm.jpg (39162 bytes) L1000627sm.jpg (33002 bytes)
Tower / Beam Fixture Element / Beam Fixture (3) Gamma Match
     
L1000766sm.jpg (99273 bytes)  
Over a period of time Karen designed and computer modeled her 20m long
boom yagi concept; running a number of radiation pattern plots until she
achieved a suitable DX antenna. She not only designed the antenna but also
machined all the aluminum parts and assembled the structure, including
mounting the antenna to the tower.
 
Yagi @ 42'    
     
20mspc.jpg (101627 bytes) 20mdata.jpg (74870 bytes) 20mpp.jpg (142975 bytes)
SWR Graph Element / Boom Dimensions Radiation Pattern Plot
     
After installation SWR was below 1.4:1, actual antenna SWR should be much lower
with specific attention to the telescopic element lengths and the gamma match.
 
Project Facts: 3 Element 20m Long Boom Yagi
   
  22' Beam with 3 - 32' Telescopic Elements
     
  Feed Line Coupled via Gamma Match
     
  42' Elevation on Tower
     
     

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