2019-12-10   06:54:06

 My  End-Fed  Very Long-Wire  Antenna 


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I have used an End-Fed Long-Wire antenna for many years.
I have used it on 80M, 40M, 20M with 1:1 SWR, 
measured via a SWR/AntTuner at base of Coax.

... I did NOT try for the shortest End-Fed Long-Wire possible.
... I DID USE  a very Long length, 177 ft,   not in a straight line.   
... I DID USE a  lengh = 5.3 odd quarters on 40M, and 11 odd quarters on 20M,  aprox.  

It is 177 feet long, up 17 ft,   
layed out in the shape of a letter "Z" , with aprox. 60' on each leg of the "Z",
via a 1:1 Current Balun ( Balanced to UnBalanced ) , 
fed via 52 Ohm Coax, 32 ft long, 
and controlled by a Antenna Tuner.

It is a copy of the BASIC SIMPLE LONG WIRE ANTENNA found at w8ji website for antennas

and http://www.w8ji.com/long_wire_antenna.htm


Design Info based on this   W8JI article.  

His information is available on his website,  and is extensive and easy to read.
my system is build from his  Long-Wire  "Basic Simple System"   on this page  .
and a very informative analysis of counter-poise on this page 

...  and  there is  much, much more on his web-site. 

Documentation for W8JI Long Wire Antenna  (click for PDF version of this page )

Note: Quarter-Wave above Ground for 20M is 17'.
Note: Quarter-Wave above Ground for 40M is 32'.
We find that 1000 mile 20M contacts to New England are common
... because the Radiation Angle is low .
We find that 500 mile 40M contacts are common
... because the Radiation Angle is medium.
Radiation Angle is greatly affected by the height above ground.

My   W8JI LongWire    has been 177 to 225 ft long, up at 17 ft,
running in the shape of "Z", 

now trimmed  to aprox. 177 ft, 
and connected to the coax via a Current Balun to match Balance-to-Coax. 
Current BalUn 1:1 is connected to 52 Ohm (coax is 21' long). 

The very long-wire maintains odd-quarter wave-lengths for target bands 

therefore No impedance changing Balun is required.  

Antenna length is trimmed to bring a 50 Ohm node near the Coax.

It has aprox. 5.3 quarter-wavelengths on 40M 

and aprox. 11 quarter-wavelengths on 20M. 

The Antenna Tuner is a simple HeathKit HFT-9 QRP ( cap-coil-cap double-"L" )

     which is the Standard Antenna Tuner design used by everybody. 

The Long-Wire  zig-zags across the house and back yard 
   with angles tighter than 90 degrees,
   with last 15 ft hanging  on a wooden fence. 

To Adjust for Lowest SWR  on 40M and 20M,
I roll up the far end of the antenna about 6' at a time, into a simple hand-loop,
wrap that with black rubber tape and leave it hanging. 

Then I go into the shack ... and vary the antenna-tunner,
until lowest SWR is obtained on each desired band (40M, 20M). 

Certain antenna lengths give 10Mhz, 14Mhz, 18Mhz,
( but 40M , 20M SWR goes up to 1.5. )

The standard adjusted length (177 ft) gives 3.5Mhz, 7Mhz, 10Mhz, 14Mhz
at near  1:1 at the SWR/Antenna-Tuner.   
... 80M tunes narrowly   
... 40M  tunes broadly
... 20M tunes very broadly 
...  all to 1:1 . 

I run 1 W QRPp/CW into the Long-Wire,
and have worked all states, and half of Europe, and Hawaii three times, but not Alaska
with my HW-8  1977  tranceiver.  
It Seems to be efficient enough for my  ONE WATT  20M  system.   

Below, the diagram shows an "L" antenna ,   but  mine is all horizontal. 


The Counterpoise wire runs down from the 17' pole,
then along the brick side of the house, 
and attaches to the back fence ,  ungrounded.
Never Ground this Counter-Poise ( SWR will go way up )
My counter-poise is about 20' long, and Not Grounded at the antenna. 
My counter-poise slopes down from the 17' metal pole to 8' at a wooden fence,
and is about  17' long ( 10% of antenna length ).

The Counterpoise is not grounded to the earth 
and only  grounded to the transceiver system.  
Check with the  W8JI  site for this exact specification.

Only the Coax Shield is grounded,  
and only  in the shack, at the Antenna-Tuner,
along with the normal shack equipment grounds,
and has a very close ground rod. 
This Long-Wire is grounded only at the connection
of the coax to the antenna tuner,
grounded ONLY inside the shack, right at the tuner. 


The Counterpoise is positioned off the feed-end of the "Z" shaped LongWire,
and there is about 60' on each leg of the "Z".


The  1:1 Current Balun has been placed outside, at 17'  
where the Long-Wire and the counter-poise are attached.  
RF in shack is minimal.    
Closely matches this diagram from  W8JI