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Wonder why seems to
be a habit use a series coil to tune out the capacitance of the
136kHz aerial, instead of more normal sort of matching - using T- or
L-network
Below is shown some impedance for a thought antenna (had to enter some
radial length for the program to work) using ENDFEED.exe provided by G4FGQ
H. Height, metres
.. 10.0
N. Number of buried radial wires .
2
L. Length, metres .. 150.0 R. Length of
radials, metres ..... 50.0
W. Wire dia, mm
.... 2.00
D. Diameter of radial wires, mm ..
1.0
F. Frequency Kilo-Hz 136 S. Strap length to
radials, metres 3.0
G. Ground
characteristics:- Average soil: R = 100, K =
12
H+L+S = 0.074
wavelengths.
R ohms jX ohms Tune out jX
with
FEEDPOINT INPUT
IMPEDANCE:
18.9 -1096.1 1282.7
micro-Henrys
-------------------------------------------------------------------------------
<-- Transcvr Shunt
L Antenna -->
T-NETWORK L & C
values: 142
pF 3666.6 uH 295
pF
-------------------------------------------------------------------------------
<-- Transcvr Series X
Antenna -->
L-NETWORK L & C
values:
2086.4 uH 3328.4 uH
Alternative L & C
values:
656 pF 794.7
uH
-------------------------------------------------------------------------------
LOSS
in T-match coil 25.4 % of Tx Pwr
GROUND ELECTRODE SYSTEM, INPUT Z
in antenna conductor
3.3 % .. ..
.. DC
Resistance 2.9 ohms
in soil in
vicinity 42.6 % .. ..
.. RF
Resistance 7.2 ..
in system of
radials 28.6 % .. ..
.. RF
Reactance 7.0
..
-------------------------------------------------------------------------------
Overall
power radiating efficiency .. 0.05 percent
Overall
loss relative to ideal system 33.1 decibels or 5.5
'S-points'
Select H,L,W,F,N,R,D,S,G to
change data, B(egin again) or Q(uit program)
you find the program on the link below
>========================
>Free Radio Design
Software
>Go to http://www.g4fgq.com
>========================
73,
Jan_Martin
LA8AK (in JO38XC
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