Ask Michael, KB9VBR: Does my end-fed half wave (EFHW) antenna need a counterpoise?

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Published 2023-08-06
A viewer asks: Is it correct to say that a counterpoise is not needed for an End Fed Half Wave (EFHW) antenna? Dave and I tackle this somewhat contentious subject and give the definitive answer to EFHW counterpoises.

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All Comments (21)
  • @HAMRADIODUDE
    Good video. There definitely is controversies regarding a counterpoise or not. I feel like Dave was very well spoken about this topic.
  • If you don't have one already, use this as an excuse to get some sort of antenna analyzer. NanoVNA, MFJ, Rigexpert, whatever you end up buying, they have one for just about every budget. In the end, I think just experimenting with different configurations to see what works and what works better is time well spent. Might be a good time to try out WSPR as well. Personally, I have an EFHW for 10m about a half wavelength off the ground, parallel to the ground and added a tuning stub to get a slightly better SWR. I've only relied on my radio's SWR meter and generally run QRP and occasionally up to maybe 20 watts. I've worked Asia, Canada, Mexico - South America, Western Europe and almost have all 50 states. I realize not everyone has room or trees that high to do that so I've also run it vertical or sloper from the top of a mast. All work pretty well. In the end, it's all about results. Make a contact and feel successful.
  • @ipduffy
    I was curious about why I was getting erratic results when I was doing FT8 on WSJT-X with my EFHW antenna. Receive worked just fine and I could hear / decode traffic from all over. As soon as I enabled transmit, everything got very garbled and messy on the waterfall. I figured I was getting RF on my rig somewhere but wasn't sure where / how. This explains it. Choke ordered from DXE and we'll see how FT8 works now! Thank you so much!
  • ABP - Always Be 'Poisen Great Explanation of why/why not to use a counterpoise!
  • @jefft2553
    Great topic. Thanks for the information.
  • To Dave's question about lower vs higher feed point height and how it works with regards to a counterpoise, I do not have a choke on my coax and do not have a counterpoise in place, the feed point is over 20' in the air with the far end about 30' up and it plays really really nice.
  • @CaptainLang
    Is an end feed antenna with a counterpoise really an off-center fed antenna? Or does the counterpoise function just to serve as a ground and not as a radiator?
  • @AlanElBee
    Great video, Michael, I'm glad I found this! 73, K7KS
  • @mattstosh6960
    My EFHW is from myantennas It is 6 feet off ground at feed point and 40 feet off ground at far end. My coax runs from feed point 6 feet towards ground and then the remaining coax runs along ground 60 feet (like Dave said). I've made over 500 Q's during 2023 already. 80m @1:1.5 and the remaining bands (40 - 30 - 20 - 17 - 15 - 10) are close to 1:1.2 except 17 which is 1:1.8. Greet antenna.
  • @martyh9309
    I run an EF that is 289' from end to choke on the coax and a common mode choke at the receiver. The wire is 203' long. Very quiet, tunes all bands from 120 to 6 end to end and SWR is less than 3:1 down to 1:1.. I've worked 99% of all stations I can hear on 100W. From APAC, SA, South Africa, Tasmania, Japan, eastern europe, russia,etc... It is a very tall Z shape when viewed from below and 45' down to 15'... I started with a 155' Palomar Bullet kit and modified it. Love this antenna. The choke was moved around to tune it and I don't have anything dropping down until after the choke into the shack. The transformer is 40' up in the air. And the choke is about 20' in the air about 25' from the shack.
  • @SkyCharter
    The answer is no. 1:47 Please test a small transmitter located at the transformer feed of the EFHW without coax or any additional wire. The EFHW dipole will radiate the same power as a center fed dipole less a bit of loss (~1 dB) caused by the transformer. I've done this test several times confirming no need for a counterpoise of any sort.
  • @robertmeyer4744
    From doing portable for many years going place to place .I can say the counterpoise can change. also the length of end fed half can change from location to location. wet ground vs dry ground vs snow on ground. how high up is the unun . all can change loading of a antenna . even the weather can . some times adding more counterpoise can broadband SWR more. so the answer is whatever works well for your location of you EFHW . same goes for the 9:1 . some have 49:1 and a 1:1 bult in. that will need a counterpoise. I use the off set center fed dipole. 40 to 6 meter. that has both transformers in it. the short element is the counterpoise. harder to set up in a park. EFHW is quite easy for quick set up. I had the 49:1 near or on ground and going straight up or sloper . just lean DX commander pole into a tree. done. any fiberglass pole. MFJ has a nice one. just bring a counterpoise wire . you may need it. and may vary on different bands. sometimes a counterpoise can bring down the noise and can increase it. try both ways whatever works better go with that. 73's
  • @BusDriverRFI
    The correct answer is that it needs to match the impedance of your impedance transformer. If you use a 49:1, you need enough on the opposing side of the long portion of your antenna to be long enough to match 2450 ohms. If you have a 64:1, you will need enough to match 3200 ohms. YMMV based on your specific situation.
  • @WG7D
    Good info. Thanks 😊 WG7D
  • @ggggg4030
    What would be helpful is showing us what it looks like when rf is coming back in the shack. Then demonstrate remedy options and the results
  • @tulenik71
    :D a friend of mine was surprised I use a coax shield as one of radials when using my center loaded vertical :D having "only" 8 5 m radials, adding another one is usually measurable (well, today, after a week of raining = good ground conductivity it is not visible). My idea originated from using coax braid as a counterpoise of EFHW antennas.
  • @503Nick
    20-25’ on a 40 m efhw. 40-50’ on a 80 m efhw. Then a common mode choke. Then any length to your radio. Palomar and PackTenna both support these measurements
  • @n0vty873
    I run a choke at both ends of the coax with a counterpoise
  • @Marty48034
    Could I use a 1:1 unun for an RF choke? I'm pretty new to this, so I'm really struggling with the choke idea. (I'm thinking something like the LDG RU 1:1.) Thanks!