W2UP recently queried the reflector about the result of pointing
stacked tribanders in exactly opposite directions (180 deg). My modeling
results of this configuration were as follows:
Modeling Software: NEC-2
Ground Model: Sommerfeld-Norton
Ground Dielectric Const: 13
Ground Conductivity: 5 mS/m
Taper: W6QHS Method
Segs/Halfwave: 50
Antenna: Force 12 C3
Mast Position: Center of boom
Frequency: 14.2 MHz
Stacking Heights: 72/105 feet
Lower Ant Upper Ant
Azimuth Azimuth Gain
-------------------------------------------------------------------------
0 deg 0 deg 14.65 dBi @ 11 deg elev Both in phase
0 deg 0 deg 11.01 dBi @ 14 deg elev Lower only
0 deg 0 deg 11.26 dBi @ 9 deg elev Upper only
None 0 deg 12.01 dBi @ 9 deg elev One C3 @ 105 ft
0 deg None 11.84 dBi @ 13 deg elev One C3 @ 72 ft
180 deg 0 deg 9.34 dBi @ 10 deg (up) 9.08 dBi @ 11.5 deg (low)
Stacking Heights: 52/105 feet
Lower Ant Upper Ant
Azimuth Azimuth Gain
-------------------------------------------------------------------------
0 deg 0 deg 14.29 dBi @ 11 deg elev Both in phase
0 deg 0 deg 12.17 dBi @ 14.5 deg elev Lower only
0 deg 0 deg 13.19 dBi @ 10 deg elev Upper only
None 0 deg 12.01 dBi @ 9 deg elev One C3 @ 105 ft
0 deg None 11.43 dBi @ 18 deg elev One C3 @ 52 ft
180 deg 0 deg 10.53 dBi @ 10 deg (up) 9.29 dBi @ 14 deg (low)
Actually, these results show several effects worth thinking about.
73 de Bruce, WA7BNM (bhorn@netcom.com)
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