I ran some analysis using AO and Nec Wires for the
simple pennant design. The AO/NW definition file is:
flag1 ant- pennant point fed
point fed pennant 1.83 MHz
3 copper wires, feet
bot = 6 ; bottom
top=14 ; top length
xl = 29 ; x of point
z1 = bot + top ; z of top
z2 = top/2 + bot ; z of point
x = xl ; x of point
1 x 0 z2 0 0 z1 #14
1 0 0 z1 0 0 bot #14
1 0 0 bot x 0 z2 #14
1 source
Wire 1, end1
1 load
Wire 2, center 900 ohms
Sweep results for 160 to 40m (Nec Wires)are:
1.800 MHz
Sommerfeld-Norton 1900.GND
Diel const 13, cond 5 mS/m
31ø elevation
15 segments, 15 unknowns
Fwd Gain -36.46 dBi
/B 45.65 dB
Impedance 1016 + j 21 ê
SWR 20.32
Losses 10.33 dB
3.600 MHz
fwd Gain -25.72 dBi
F/B 35.13 dB
Impedance 1063 - j 23 ê
SWR 21.28
Losses 9.69 dB
7.200 MHz
Fwd Gain -16.32 dBi
F/B 28.34 dB
Impedance 1075 - j 178 ê
SWR 22.09
Losses 8.77 dB
THese are very broadband and a matching transformer
will have almost 1:1 Swr on all 3 bands.
I found that almost any shape wire works just fine and
that the dimensions are not critical. The larger
shapes result in lower losses.
Pat W0OPW
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