Part 4: Vertical Polarization

Mismatched polarization can yield a 30 db signal loss (per the Getting Started column on antenna polarization, by W1ZR, in the July 2010 issue of QST). Since this antenna may be used to communicate with mobile radios that typically use vertical antennas, we need to find out how it behaves when oriented vertically.

By changing one number on the GM card we can rotate the antenna 90 degrees around the Y-axis:
GM  0  0  0.000E+00 9.000E+01 0.00E+00 0.000E+00 0.000E+00 %fE+00 0.000E+00

The results are very similar :  (click images to enlarge)

 Horizontal
yagi4elem_2m_v3.nec
 Vertical
yagi4elem_2m_v4.nec
 
 
 
 

Most of the differences are minor and probably due to the precision of the calculations, however the vertical polarization has  a significant gain loss of almost 4db vs horizontal polarization. Still, compared to a mismatch in polarization, 4db is minor.

Max Vertical Gain vs Max Horizontal Gain
(click image to enlarge)


Antenna Height

Here are the results of running the vertical model at different heights above ground: (click image to enlarge)

 
 
 Theta vs Height in Wave Lengths  Theta vs Height in Meters

The variation in theta is less than when the antenna was horizontal, but the pattern is the same.


Previous - Part 3: Answers, Horizontal polarization
End of Exercise
2m Yagi Antenna Analysis
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yagi4elem_2m_v3.nec
(1k)
JERRY DUNMIRE,
Apr 20, 2012, 9:11 PM
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yagi4elem_2m_v4.nec
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JERRY DUNMIRE,
Apr 20, 2012, 9:11 PM
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