whip antenna calculations
I am looking for a .xls spreadsheet (or something that works under LINUX),
to calculate the equations for matching common maritime mobile HF whip
antennas:
8 ft
10 ft
15 ft
23 ft
40 ft (backstay, approx 5/8 on 20 Meters)
I want to calculate the matching parameters including voltages generated
in the tuner for the 1.8 3.5 7 10.1 14 21 28 MHz ham bands and the 2 4 6 8
12 16 and 22 MHz marine bands.
The ARRL ANTENNA HANDBOOK, 18th edition, chapter 18, has some equations
and a table of calculated values for a 8 ft whip on ham bands. I wish to
duplicate the calculations and figure out the voltage maximums for
component values for, say, 100 W key down power.
Take for example the 1st row of the table:
BASE LOADED 8ft whip
F=1.8 MHz
Loading L = 345 uH
Rc Q=50 = 77 ohms
Rc Q=300 = 13 ohms
Rr =0.1 ohms
Feed R = 23 ohms
Matching L = 3 uH
Now at 1.8 MHz
XL of 345 uH = +j3902 ohms
Do I calculate the current from P=I*I*R so for
Rr = 0.1 ohms, I = sqrt(100/Rr) = 31.6 A
so V XL is I*R = 31.6*3902 = over 123 KV? (seems excessive)
or do I use the R values of 77, 13, or 23 ohms? (4.4 KV, 57 KV, 8.1 KV )?
Do I multiple all RMS voltages by sqrt(2) to convert RMS to PEAK?
Greg
VE0ACR
gblair _at_ sympatico _dot_ ca
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