Transcript Storm Water Permit Training

End Fed Antennas
End Fed Long Wires
Presented at Ham Com 2013
Portable Operations
Stealth Applications
Antenna Types
• Antennas come in two basic types –
Resonant and Non-Resonant
• Resonant types are dipole, yagi, etc. They
have a resonant frequency (usually on the
band they are designed for)
• Non-Resonant antennas are long wire,
G5RV, etc. They are not resonant on any
band and can work on multiple bands.
Antenna Types cont’d
• There are many different variations of
each of these types of antennas.
• Each type of antenna has advantages,
and disadvantages.
• Resonant antennas have resistance only
at resonant, all other frequencies will have
an impedance and resistance.
• If you model antennas it will give the SWR,
Resistance, and Impedance at the
different frequencies.
Antenna Types cont’d
• We modeled an 80M dipole 122’ long at a
height of 30’ (468/3.8Mhz = 122’).
• We used EZNEC – this is a popular
antenna modeling program that amateur
radio operators use.
• Resonance is defined as Capacitive
Reactance = Inductive Reactance (leaving
resistance)
80M Dipole – Resonant Freq. 3.875 MHz
Resonant Freq. ~ 3.875 MHz – R = 28.26, Impedance 2.24, SWR = 1.77
80M Dipole – Off Resonant Freq. Low 3.80 MHz
Resonant Freq. ~ 3.800 MHz – R = 41.74, Impedance 32.82, SWR = 3
80M Dipole – Off Resonant Freq. High 3.95 MHz
Resonant Freq. ~ 3.950 MHz – R = 41.74, Impedance 32.82, SWR = 2.77
Antenna Types cont’d
• Several things to notice. The resonant
frequency is at the dip. Here it is at ~ 3.875
MHz.
• The SWR is 1.77 with a resistance of 28.35
ohms and a reactance of 2.23 ohms so it is
very close to the resonant frequency.
• Why isn’t it 50 ohms? It is too close to the
ground – which changes the values.
• The characteristic impedance of a dipole is
72 ohms.
Antenna Types cont’d
• Most antennas will contain an impedance
that is not at 50 ohms.
• All antennas will have an reactive
component (when it is not at resonant
frequency).
• We usually use an antenna tuner to match
the transceiver to the antenna.
End Fed Antenna
•
•
•
•
Most antenna are fed in the middle.
Some antennas are fed off-center.
The End Fed antenna is fed at the End.
There basically two types End Fed
antennas: Resonant and Non-Resonant.
• On a Dipole the impedance is low in the
middle and high at the ends.
• End Fed antenna has a similar type of
impedance.
End Fed Antenna cont’d
• The impedance at the end will be high, so
you have to have a matching network to
bring the impedance down to a low
impedance for the coax.
• Half Wave antenna usually have a difference
impedance when they are close to the
resonant frequency.
• Half Wave and Long Wire End Fed antennas
usually use different matching networks.
Antenna Wire 30'
a
Orange
A
b
Black
SO-239
B
c
Green
C
End Fed Long Wire Matching Unit
SO-239
Antenna Wire
Half Wave
Matching Network for End Fed Half Wave
End Fed Long Wire Antennas
• The matching network is usually made
with a toroid core.
• Common cores that have been used are
T106-2, T130-2, FT-140-43. You can
probably use just about any toroid that can
operate on the frequencies you need.
• T-106-2 is an Iron Power toroid – 1.06”
diameter - # 2 mix
End Fed Long Wire Antennas
cont’d
• FT-140-43 is a ferrite toroid – 1.4”
diameter and type 43 mix
• T106-2 $1 – $1.50; T130-2 $1.60 - $2.00;
and a FT140-43 $2.50 – $3.50.
• Probably any toroid with a TXXX-2 or a
FTXXX-43 would probably work.
• The Mix is just a designation, this is used
to determine the frequency range etc.
Winding the toroid
• The toroid is wound using 9 turns of trifilar
winding.
• Trifilar means 3, so there are 3 wires
wound 9 turns on the toroid.
• This is a UN-UN type device (UNbalanced
to Unbalanced).
• Turns ratio is 3:1, impedance is Turns
Ratio Squared 32 = 9.
Antenna Wire 30'
a
Orange
A
b
Black
SO-239
B
c
c
Green
b a
A
C B
T106-2 toroid – 9 Trifilar turns
C
Connecting the toroid
• Pay attention to the Letters in the above
picture. You will have to connect them
properly to make the matching network
operate properly.
• Connect the left side Black (b) to the right
side Orange (A). Remove the insulation
and solder close to the core.
• Twist the Green wire left side (c) with the
Black right side (B) – this will solder to the
center of the SO-239.
Connecting the toroid cont’d
• On the Green wire right side (C) attach a
small lug. This will connect to the outside
of the SO-239.
• Solder a large lug to the Orange wire left
side (a). This will connect to the Antenna
terminal.
Finishing Matching Network
• The Matching Network should be installed
in a weather proof housing of some sort.
• We have used PVC pipe fitting - 1 ½” Cap
and 1 ½” slip plug.
• We have also used ¾” or 1” plastic LR
electrical fittings. This allows more room
and you can repair it, if needed.
Matching Network in a PVC Cap and Plug
Matching Network in an Electrical LR fitting
Selecting Long Wire
• You will need to attach a antenna wire.
• Select a size suitable for the bands you
are going to be operating and your specific
surroundings – as a general rule the
longer the better.
• Avoid a length that is ¼ wavelength or
multiple ¼ wavelength.
• Common lengths are shown on the next
slide.
28.5'
17'
30'
36'
20
6M
10M12M
6M
15M
44'
49'
53'
40
17M
6M
72'
88'
60
12M
15M
10M
17M
12M
98'
80
40M
20M
10M
59'
20M 15M
100
60M
17M
102'
30M
½ Wave Dipole
1 Wave Dipole
1 ½ Wave Dipole
Suggested Lengths
For portable operations the 17’ or the 30’ are the most practical. I use a 33’
fiberglass pole and a quad-pod. I can erect the antenna in about 5
minutes.
Operating the End Fed Antenna
• This antenna does not require ground
radials.
• It uses the coax as the ground. You
should use 30’+ of coax for the antenna to
work correctly.
• It may produce some RF back into the
shack, if it does – install a line isolator
before the coax enters the shack.
Home made Quad Pod with 33’
fiberglass Pole (MFJ 1910)
Testing Matching network with a 33’
wire
Test SWR with 70’ RG-213 and
MFJ – 259B
30M
SWR
R, Z
SWR
R, Z
SWR
R, Z
SWR
5.0
200
5.0
200
5.0
200
5.0
200
4.0
150
4.0
150
4.0
150
4.0
150
3.0
100
3.0
100
3.0
100
3.0
100
2.0
50
2.0
50
2.0
50
2.0
50
1.0
0
1.0
0
1.0
0
1.0
0
75, 80M
3.50
3.50
3.50
40M
7.0
7.15
7.30
10.1
14.0
R, Z
20M
14.175
14.35
17M
SWR
R, Z
SWR
R, Z
SWR
5.0
200
5.0
200
4.0
150
4.0
3.0
100
2.0
1.0
18.1
R, Z
SWR
5.0
200
5.0
200
150
4.0
150
4.0
150
3.0
100
3.0
100
3.0
100
50
2.0
50
2.0
50
2.0
50
0
1.0
0
1.0
0
1.0
0
15M
21.0
21.225
21.45
28.0
10M
28.5
29.0
50.0
Test SWR on 30’ wire with 70’ RG-213 using MFJ – 259B
(matching network using a T106-2 core)
R, Z
6M
50.4
51.0
W5WF using MFJ-1910 33’ Pole
W5WF permanent installation 33’ Pole
Related Information
Videos on End Fed Antennas
http://www.youtube.com/watch?v=uWkpQ785Pjo&feature=rela
ted Video on using End Fed Antenna with MFJ 1910 33’
fiberglass pole
http://www.youtube.com/watch?v=yrgU5IMXlQY&feature=relat
ed Video comparing a PAR end fed dipole antenna to other
antennas
These antennas work great using a fiberglass pole. You can
use an MFJ 1910 or get one off eBay. (Do a search on eBay
for fiberglass poles or look for fiberglass pole by Jackite.)
Material List
1
1
1
3
4
4
1
1
1 ½” PVC Cap (different enclosure)
1 ½” Slip Plug (different enclosure)
powdered iron toroid T106-2, T130-2 (FT140-43)
24” pieces of 22/20 gauge solid insulated copper
wire in orange, green, and black
6-32 x 3/8” machine screws
#6 nut (for SO-239 connector)
SO-239 panel mount connector (4 hole)
10-24 x ¾” machine screw and nut
Material List cont’d
2
1
1
2
1
30’
#10 flat washers
#10 lock washer
#10-24 wing nut
#10 wire lugs
#6 wire lug
#14 AWG (16, or 18 gauge will also work) insulated
stranded wire antenna
Modification
• We have added a Ground terminal to the
existing design.
• This will cut out using the coax as the
ground.
• Not sure at this time if this improves
antenna operation or not.
Antenna Wire 30'
a
Orange
A
b
Black
SO-239
B
c
Green
C
End Fed Half Wave
• Resonant on a particular band
• No Antenna Tuner is required
• Usually covers the whole band with less
than 2:1 SWR (except 10M)
• Good for 100 watts SSB/CW – only good
for about 50 watts on RTTY/PSK31
• Easy to put up
End Fed Half Wave cont’d
• The matching network is a toroid and a
capacitor (like a miniature antenna tuner)
• The capacitor is made from coax (RG-174)
• Similar to a PAR EndFedz half wave
antenna
Web Site
• You can get the presentation and the hand
out at:
www.WB5CXC.com/HamCom13