Grounding a Counterpoise on End-Fed Half Wave Antenna ( 

I've been using an EFHW fron NI4L for a little over a year, due to limited space and an HOA. It has been very noisy and difficult to to get reasonable SWR. Thanks to your videos I have made adjustments that have greatly improved SWR and transmission pattern. Added a 0.05 wavelength counterpoise, charted SWR across desired bands and adjusted wire length. Added ferite chokes on both ends of coax. Making DX contacts to Asia and Europe now on

Dave I hv a My antennas 40-10, extended to an 80-10. A ground rod was placed beneath the box. From the ground rod, I used an alligator clip and 14 gauge wire, which I ran on the grass, parallel to the antenna wire(134 feet). The difference, especially on 160 and 80, is an s unit or two. I am always being told what a nice signal n audio is coming from the antenna and my 7300. This reflector wire or counterpoise wire, seems to do the trick. I hope others try this on the already, fantastic‘My antennas’ antenna😁. The kicker is: Along with my trustee Mfj-939 tuner and the counterpoise, I work 160 nightly, with good results throughout the northeast from my location in so Connecticut. Just thought u wld like to know. Billy

Thanks!

Hi Dave, love your presentations but I would like to make a few points of clarification regarding this video. 1) In a auto transformer configuration the primary and secondary share the same winding, and the common is the very bottom of the winding and this would be where the counterpoise connects. 2) In a auto transformer design the number of turns on the secondary includes the number of turns on the primary (consider the primary just a tap on the secondary coil in this case), so the total amount of turns for a 49:1 transformer using 14 turns on the secondary would be 14 total turns with the tap for the primary being at turn 2. Note: I suspect most of the EFHW transformers sold are not auto transformers but rather separate primary and secondary windings which are tied together on their low side (probably wound bifilar or twisted). In that case for a 49:1 transformer with a secondary that has 14 turns you would indeed find a totally separate 2 turn winding for the primary. 3) The compensation coil that you mentioned is not there for 80 meters, its real purpose is to add more and more inductive reactance when operating on the harmonically operated bands to help shift the frequency of resonance down on the higher bands (the harmonically operated bands). If you don't shift the frequency of resonance down on the harmonic bands their frequency of resonance is typically higher than desired. You can easily see this via modeling that the harmonically operated bands have their resonant frequency higher than you would expect. As an example a 40 meter EFHW antenna resonant at 7.0 MHz would harmonically be resonant at 28.0 MHz if you just multiply 7.0 MHz by 4, but in reality the antenna is resonant closer to 29.0 MHz and therefore the compensation coil is used to add more inductive reactance on 10 meters which helps lower the resonant frequency by a greater amount than it would on the lower bands as an example. 4) For consistency I use a choke on the coax feedline approximately 0.05 wavelengths down from the EFHW transformer so that the counterpoise is just the first 0.05 wavelengths of the outside of the shield on the coax on the lowest band of operation and this is based on work done by AA5TB which I have confirmed via 4NEC2 modeling, and this offers many benefits. I just wind 14 turns of the feedline onto a FT240-31 toroid core to form the choke and this choke is based on work done by K9YC. You can still ground the shield of the coax (that's beyond the choke) where it enters the shack for static discharge purposes if desired, but this will have no effect on the actual performance of the antenna. The choke makes the EFHW antenna a very robust design as the coax beyond the choke does not alter the performance of the antenna (length of coax is no longer a unknown variable) and the choke eliminates the need for a separate counterpoise as you have already defined a very specific counterpoise using the outside of the coax that comes before the choke, and it helps prevent common mode noise that's induced on the outside of the long run of the coax shield that's beyond the choke from making its way to the feedpoint which helps reduce noise on receive. Just FYI, Don (wd8dsb)

Nice job Dave. Love the topic as I have purchased a MyAntenna EFHW, not yet installed as I am still 'designing' the supports. Plan is to mount it horizontally at 25'. Wanted to model the antenna but don't have the experience with EZNEC or MMANA to get the parts all connected together correctly. Still working it. Thanks for sharing all the info. I have saved the video to watch again.

Many EFHW antennas (with the UnUn) come with a somewhat longer antenna wire. One has to tune the antenna wire in the position the antenna is placed. That is because not everyone puts the antenna at the same spot, hight or manner. In my case (HyEndFed) I had to trim the wire about 1.3 ft (40 cm) to get an overall 1.2 SWR. I did not need an extra counterpoise; the UnUn is about 8 ft (2.5 mtr) up. Greetings from the Netherlands, keep up the fine videos, 73, PD0PSX.

This setup is great! In my scenario, what worked best is having the box close to the ground (around 12” plus or minus) with the wire sloping upward. Wire was 133ft long to work 80-10. Wire was about 20ft high. Wire wasn’t ideally straight nor horizontally parallel to the ground as I had to navigate an L shaped backyard. When I connected ground lug to earth ground, it produced more noise so I left it disconnected. RG8X feed with 31 core at 17ft and a 43 and 31 core at the rig. Total coax run was around 75ft . First 17ft from box was rg8x and the rest was lmr400. This setup worked wonders for me! LOL Dave @ 6:25 !!!

I have an antenna up 60 feet supported at both ends by trees. I put screen door springs on both ends (mechanically connected not electrical), and it has stayed up with no problems for 15 years now. I've had many thunderstorms, microbursts, and possible mini-tornadoes go through. Can recommend using them.

Im betting into using end fed antennas. Thanks for this video Dave! 👍

Understood my doubt on counterpoise finally. Thank you Dave. VU2YUK

My EFHW is fairly straight and 75' above Earth. Homebrew w/ 49:1 2 core unun & 22' Counterpoise. All wire is 12Ga stranded. Grounding the Counterpoise noticeably reduced noise and helped flatten multiband SWR (MFJ Analyzer sweep). I can tune 80 no problem with ATU. Single 6' Ground-rod. I use a large RF choke to connect Earth to ATU in station. Fed with coax. Best antenna I ever had. N2EYE

Hi Dave. Thanks for the video. You mention in the video about putting a lightning arrestor on the coax before entering the shack. I'm setting up the Myantennas 8010 such that all but maybe a foot of the coax is inside. The UNUN will be outside under a covered porch about 10' up. Where would a lightning arrestor go, or do I even need one? Thanks

Dave, your videos are always helpful for me! It's what helped me get into amateur radio. Quick question: do you think adding a grounded counterpoise to my efhw transformer will prevent the GFCIs in my house from tripping?

I use the myantennas EFHW-4010. It does not work on 80m but also has the in-line inductor.

When building an EFHW matching unit, first tune the matching unit using a resonant length of wire. Measure the impedance. If it's < 50 ohms, remove some turns from the secondary coil. If it's over 50 ohms, add some turns. 7:1 turns ratio is usually pretty good for the middle bands. You may need a higher ratio for the lower bands. The little loading coil helps make the antenna resonant on the bands for which the wire is 1, 1.5, 2, etc wavelengths long. Without it, a resonant length on 40m will be resonant just about the 20, 15, and 10m bands.

I have watched your end fed antenna videos. Everything you have shown or said about them is really good and ideal in formation. My question for you is what is considered as a half-wave wire. My wire antenna is from MY ANTENNA and is 117 feet. And it was as mentioned in this video over 2.1. I have been told by other hams, that theirs are 60, 90, and 100 feet in length. So my questions are, #1. how do I figure out in formula, that length of this wire should be? #2. should I cut it to 100 feet? Thank you a reply or even a video about half-wave lengths of wire. 73 N6ZKI. Leonard Foard.

What are the implications is the feed coax is long (100 feet) but is buried?

Lmao off at forgetting your thought mid-sentence. It's a classic trap that gets me. Way to power through.

If one were to add a common mode choke in your recommended configuration, where would it go? My planned order is antenna transformer via coax to lightning arrestor, ground rod, and then on to the transceiver. Or do you think some ferrite beads would work as well?

Dave really like your videos, is there any place currently for AM boat anchors ( EF Johnson ranger) on ham ?.

Question, if a station is on a 2nd or a 3rd floor and a "normal ground" is not in the cards, can one use the round hole in a typical 110 volt oitlet? Use a "banana type" end and push it into the round hole on the plug? It is the ground for a building, wouldn't it work for a antenna type ground if thats all thats available?

Hello David!!! How do I unlock other frequency bands in radio TYT UV-8000D! The Radio comes in the 136-174 MHz and 400-520MHz ranges. I want to use the 128,000 MHz frequency. It's possible? Thanks for the videos!

Why not cut the connection between primary and secondary and run a counterpoise from the secondary? That would get rid of the problem of RF on the coax and eliminate the need for a choke.

What happens if I make the wire element a full wavelength? Or 2 wavelengths? I have property behind me but I live at the front.

I have the same antenna attached to the top of my tower (~50+ ft) slopping. I have the ground attached to the tower which is grounded to several grounds. The coax coming down the tower goes through a coax switch box and then a lightning arrestor (which goes to a ground round) before entering the shack. The coax enters through a window pass through which is grounded as well. Just curious. Is the coax acting as a counterpoise, the tower leg or both?

On your schematic, at the UNUN you have the shield and input incorrect! they are changed!

??? The small coil on mine Dave, affects the higher bands, and brings them into a dip in the portion I want.... ( Homebrew 66 ft, 40m to 10m endfed, with 49:1, and no counterpoise..) Cheers, 73 Fred G4ZWI

please put your camera up higher…. the low camera angle only focus on showing audiences up your nose

EFHW antennas are not really end fed. It's an off center fed antenna with one side at over 95% of length and the other end is .05 wave length or only a few percent of half wave. Trying to use a counterpoise or other modifications will screw up the antenna.

First get rid of blightey gibberish, lol