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End Fed Antennas End Fed Long Wires. Presented at Ham Com 2013. Stealth Applications. Portable Operations. Antenna Types. Antennas come in two basic types – Resonant and Non-Resonant

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End fed antennas end fed long wires

End Fed AntennasEnd Fed Long Wires



Stealth Applications

Portable Operations


Antenna types
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
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 d1
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 d2
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 d3
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
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
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.




End fed long wire antennas
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
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
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.



Connecting the toroid
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
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
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.




Selecting long wire
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.


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
Operating the End Fed Antenna practical. I use a 33’ fiberglass pole and a quad-pod. I can erect the antenna in about 5 minutes.

  • 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) practical. I use a 33’ fiberglass pole and a quad-pod. I can erect the antenna in about 5 minutes.

Testing Matching network with a 33’ wire

Test SWR with 70’ RG-213 and

MFJ – 259B



W5WF using MFJ-1910 33’ Pole

W5WF permanent installation 33’ Pole


Related information
Related Information

Videos on End Fed Antennas

http://www.youtube.com/watch?v=uWkpQ785Pjo&feature=related Video on using End Fed Antenna with MFJ 1910 33’ fiberglass pole

http://www.youtube.com/watch?v=yrgU5IMXlQY&feature=related 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
Material List

1 1 ½” PVC Cap (different enclosure)

1 1 ½” Slip Plug (different enclosure)

1 powdered iron toroid T106-2, T130-2 (FT140-43)

3 24” pieces of 22/20 gauge solid insulated copper wire in orange, green, and black

4 6-32 x 3/8” machine screws

4 #6 nut (for SO-239 connector)

1 SO-239 panel mount connector (4 hole)

1 10-24 x ¾” machine screw and nut


Material list cont d
Material List cont’d

2 #10 flat washers

1 #10 lock washer

1 #10-24 wing nut

2 #10 wire lugs

1 #6 wire lug

30’ #14 AWG (16, or 18 gauge will also work) insulated stranded wire antenna


Modification
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.


End fed half wave
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
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
Web Site

  • You can get the presentation and the hand out at:

    www.WB5CXC.com/HamCom13


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