160-80-40-m-end-fed-antenna-g0csk-iss-1-31.pdf

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160–80–40m END FED ANTENNA - G0CSK
Insulator
80m
Trap
Insulator
40m
Trap
8.54m
6.55m
Mast
Height Not
Critical
Junction
Box
Ground
Spike
9.
9
m
Coax Cable
NOTES:-
NOTES:-
1.
1.
At
At the Junction Box
coax inner connects to the antenna wire (blue) and braid connects to
to the brown wire to
ground spike.
the Junction Box ,
, coax inner connect to the antenna wire (blue) and braid connected
the brown wire and
the ground
n
2.
spike.
section of the antenna is initially cut over size by 300mm, and trimmed to reduce the SWR on each band starting with
Each
40m band section
that
then
up
80m section, and finally
initially cut over size by 300mm, and cut to reduce the SWR.
2. The three wires
first ,
make
the
the end fed antenna are
the 160m section
3.
3.
If the ground is
is not very conductive add supplementary radial insulated wires on the ground to act as
counterpoise. ( 8 x 4m)
If the ground
not very conductive add supplementary radial insulated wires on the ground to act as a
a counterpoise. ( 8 x 4m)
4. To Tune the antenna Start with the 40m section, then adjust the 80m section, finally tune the 180m section.
Soldered
Antenna
wire
Coax Cable – RG58
Hole in
Drain Pipe
Coax Braid
2.5mm Dia
Copper wire
Fixing point
G8ODE
TRAP
DESIGN INFORMATION
TRAP
DESIGN INFORMATION
80m Trap 23 turns RG58
80m Trap 23 turns RG58
on 40mm Diameter plastic pipe
pipe 150mm long
on 40mm Diameter plastic
150mm long
40m Trap 11 turns RG58 on 40mm Diameter plastic pipe 80mm long
40m Trap 11 turns RG58 on 40mm Diameter plastic pipe 80mm long
G0CSK
EA5AVL
N.B.
A very useful tool for coax-traps is a program by Tony VE6YP called
"coaxtrap.exe". You can download the program from his website
www.qsl.net/ve6yp .
Graphics by G8ODE OCT 2008 iss 1.3
160–80–40m END FED ANTENNA - G0CSK
Soldered
Antenna
wire
Coax Cable – RG58
Hole in
Drain Pipe
80m Trap 23 Turns RG58
40m Trap 11 Turns RG58
On a 40mm Dia former
Coax Braid
2.5mm Dia
Copper wire
Fixing point
G8ODE
Here are the photographs two that were made using this form of construction. The
Coax has been taped over for additional protection, and the ends have been sealed by
first fitting cut plastic discs and sealing these in with silicone bath sealer
n
40 Metre Coaxial Trap
80 Metre Coaxial Trap
N.B.
A very useful tool for coax-traps is a program by Tony VE6YP called "coaxtrap.exe". You can
download the program from his website
www.qsl.net/ve6yp .
EA5AVL
G0CSK
Graphics by G8ODE OCT 2008 iss 1.3
160–80–40m END FED ANTENNA - G0CSK
Note: The
Red
&
Blue
colours
are
used simply to emphasise
the vertical & horizontal components of the antenna current.
The “X” marks the position of the traps.
1.91MHz Plots
Looking at the current distribution, it will be seen that the
1.92MHz Frequency does not cause either of the two traps to
become activated & the antenna behaves as a long wire.
3.55MHz Plots
n
Here the 3.55MHz frequency causes the 80m trap to operate
and electrically shorten the antenna. The current in the last
section of the antenna is significantly reduced
7.05 MHz Plots
EA5AVL
G0CSK
Here the 7.05 MHz frequency causes the 40m trap to operate
and further electrically shorten the antenna. The current in
the last two sections is thus significantly reduced
Graphics by G8ODE OCT 2008 iss 1.3
160–80–40m END FED ANTENNA - G0CSK
3-D Far Field Total Radiation Plot for 7.05 MHz.
The 3.55Mhz &1.92MHz plots are very similar. The “funnel” in the centre gradually disappears. In all three cases the
maximum radiation is at an angle of about 30 degrees to the ground.(see results below)
MMANA-GAL MODEL RESULTS
n
G0CSK
EA5AVL
The model only provides an indication of the expected performance of this antenna.
In practice better SWR results & hence improved efficiencies can be obtained.
Graphics by G8ODE OCT 2008 iss 1.3
160–80–40m END FED ANTENNA - G0CSK
The traps for this antenna can also be made using coils and capacitors. E A Rule G3FEW (RAOTA 1487) who is a
fellow member published this information as part of his trapped Multi-band antenna in the RAOTA journal issue OTN89
and also made the article available on the web as a PDF.
http://www.norfolkamateurradio.org/pdf/talks/G3FEW%20Multiband%20Antenna.pdf.
The table below provides details of how to make the coils. A 40mm diameter plastic tube is used for the former, and a
100pf high voltage capacitor to tune the trap for each of the HF bands.
He also suggests a way of making a capacitor from double sided glass fibre copper laminate board (PCB).. For high
powers in excess of 100 watts the high voltage capacitor should be used, because the epoxy resin used for the PCB
material may become over stressed and start to breakdown. If the capacitor’s value falls between 90pf to 110pf the
antenna Wires length will need altering..
G8ODE RSARS 1691 RAOTA 2004
Alternate Method for making Traps
1.2mm enamelled wire
see table below
Soldered antenna Wire
Hole in tube
40mm
Diam
Pipe
1mm glass fibre double sided Copper
Laminate (PCB material)
Important
1-2 mm border – no copper, to avoid
flash-over when transmitting
For 100pF Copper area 35x60mm
Table 1. LC Trap winding details. --
T ra p
10m
12m
15m
17m
20m
30m
40m
F re q M H z
28.4
24.94
21.225
18.118
14.2
10.15
7.1
T u rn s
2.5
3
3.5
4
5
8
10
E A Rule G3FEW (RAOTA 1487)
uH
0.312
0.407
0.562
0.771
1.256
2.458
5.024
C a p a cito r p F
100
100
100
100
100
100
100
Graphics by G8ODE OCT 2008 iss 1.3

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