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Old 19-Jan-2012, 6:16 AM   #19
GroundUrMast
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Join Date: Oct 2010
Location: Greater Seattle Area
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Comparison of 1/4 vs 5/8 radiation patterns

Here is a 3D model view of the radiation patterns of the common 1/4 wave whip compared to the theoretical radiation pattern of a 5/8 wavelength base loaded whip.

Both are simulated over perfect ground... which your fender will is not.

Here is the 4NEC2 code for the 5/8 WL model:

CM Base loaded 5/8 wave vertical whip antenna over a perfect ground plane
CE
SY WR=#14
SY DEL=1.868521 'Element Section Length in Meters
SY COIL=6.125e-7 'Load Inductance, Henrys
GW 1 30 0 0 0 0 0 DEL WR
GE 1
LD 5 0 0 0 1390000 'Stainless Steel
LD 0 1 2 2 0 COIL
GN 1
EK
EX 0 1 1 0 1 0 0
FR 0 0 0 0 100 0
RP 0 285 73 1510 90 0 5 5 0 0
EN


Here is the 4NEC2 code for the 1/4 WL model:

CM Simple quarter wave vertical whip antenna over a perfect ground plane
CE
SY WR=#14
SY DEL=0.755 'Element length in Meters
GW 1 17 0 0 0 0 0 DEL WR
GE 1
LD 5 0 0 0 1390000 'Stainless Steel
GN 1
EK
EX 0 1 1 0 1 0 0
FR 0 0 0 0 100 0
RP 0 285 73 1510 90 0 5 5 0 0
EN
Attached Files
File Type: pdf FM Whip qrtr vs five eigths patterns.pdf (363.9 KB, 1923 views)
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