The G4ATA EFT antenna (pat pending!)

As briefly mentioned in the "Antenna" section of my "Current Setup" page I am severly restricted for antennas.  Apart from having a very small rear garden I have issues with neighbours that are far too complicated and boring to go into here.....suffice to say that one of them believes that she is in desperate need of a tin foil hat to protect her from my cancer causing and global warming radio transmissions!  The less said the better!!

My rear garden ("yard" for our American friends!) is only 11.5m x 6.5m or 37ft x 21ft in old money.  Pretty small even by UK standards.  The image below shows the layout of the antenna as of January 2026.

The vertical section is 50mm OD aluminium attached to (and insulated from) T & K brackets.  From the top of that pole and for the counterpoise I have used 4mm PVC coated Flexweave.  The total length of the antenna is approximately 75ft and the counterpoise 35ft.  The counterpoise is raised above ground approximately 1ft.

At the feed point I have a homebrew 9:1 balun that is preceeded by a homebrew bifilar wound common mode choke that is wound on 2 x 240-T31 ferrites.  The balun performs well and makes the required impedance transformation. 

The CMC also performs well at power levels up to 200 watts from my FTdx101MP.  However, the CMC isn't so happy if I strike up my Acom 1010 and raise the power levels.  It generates heat and after a short while the SWR rises.  With the exception of 80m where it quite happily copes with 500 watts of CW for hours.  I suspect this is because the choke's impedance becomes resistive at frequencies other than 3.5MHz'ish resulting in core heating.  At some point in the future I will investigate the use of a different choke for QRO and the higher frequencies....watch this space!!  There is loads of info available on the web regarding baluns and chokes.  One of my "go to" sites is http://www.karinya.net/g3txq/chokes/
In the meantime I restrict QRO activity to 80m.

Apart from the CMC issue the next item on my agenda for this antenna is to raise it's overall height over it's whole length to approximately 4.5m.  Again, watch this space!

Below is a plot of the SWR of the EFT in it's current iteration ...... the markers are set for the CW portion of the bands.  This plot was made using my FA-VA5 designed by DG5MK using the DG8SAQ Vector Network Analyser software for the DG8SAQ VNWA .....  see SDR-Kits - note the FA-VA5 is no longer available and has been superceeded by the FA-VA6.

I am currently in the process of modelling the EFT in EZNEC to compare the real world results with my best efforts of the model in the software.....watch this space!!

Today, 10th February 2026, I had the antenna down to do some more accurate measuring of the wire to try and get it a little higher in the hedge at the side of my property.  At the same time I tried adjusting the length of the wire longer and shorter up to a maximum of around 10ft.  The wire actually measures 67ft which actually works out pretty well if you take into account a velocity factor of 95% for insulated wire.  My "target length" was 72ft that is a popular length for this type of antenna.  The vertical section is a 50mm ally pole so I'm sure there would be some VF to take into account there.

I tried lengthening and shortening the antenna with very mixed results.  Some bands improved at the expense of others for each attempt.  It was similar for adjustments to the counterpoise too so I think I've been pretty lucky to hit a sweet spot.  I'm sure that there will be those that have better results with different lengths but due to the constraints of my plot and proximity to the house (bungalow actually) etc I feel that I'm getting the best out of this particular configuration.

I did manage to get the low section a little higher into the hedge that has resulted is slightly lower SWR on 80m & 40m and marginal difference on the other bands.

Hopefully I will be able to get the horizontal section of the antenna raised some time in the next few weeks......fingers crossed for further improvements!

EFT MkII - 02/03/2026

I managed to increase the height of the horizontal sections of the antenna.  The counterpoise remains unchanged but from the top of the vertical section it now rises to about 5m supported by a fibreglass pole, then turns 90 degrees for the rest of it's length it slopes down to approximately 3m.  Below is the plot of it's SWR in it's current form



Below is the comparison of SWR values between the original and MkII versions.  Remember they both use exactly the same counterpoise and wire......the only thing that changed was the height of the horizontal section.  As you can see, there is a marked improvement on 80m & 40m.  The only band that suffered was 60m but I can live with that!  My HC-2000 ATU still manages a match to keep the rig happy!  The HC-2000 even manages to make a match on top band in spite of the SWR being over 30:1!!!

All of my contacts are automatically uploaded to Club Log and the table below shows a summary of DXCC and bands that I have worked in 2026 since 1st February using this antenna.....all CW of course.  The vast majority of these contacts have been made using 200 watts or less.

This page last updated 03/03/2026 (dd/mm/yyyy).