My End Fed Stealth Antenna
Tom Sowden, W6KAN
If you have a tall tree and lots of foliage nearby an end fed antenna can be nearly invisible – especially since there are no tell-tale feed lines. I have been intrigued by end fed antennas for some time. When I have worked stations that use them their signals almost always sound strong. One of my ham friends who lives in the Bay area recently took a trip to Placerville California to visit a distant relative. On the trip he took a portable rig and an end fed ½WL 40 meter end fed antenna. Once he got it set up with the end in a tree his signal was amazingly strong running barefoot. He did not have a counter poise and experienced no RF feedback. Listening to his signal just got my juices flowing faster – I had to have an end fed antenna.
Trying to understand the dynamics prompted me to read up on the net anything I could find about how these antennas work. The old Zep antennas floating behind dirigibles of yesteryear were some of the best examples of end fed antennas. Simple matching transformers made it possible to load up the long wires used for communication.
Note the short counterpoise wire dangling off of the secondary of the transformer. Everything I read suggested that some length of wire off of the ground side of the transformer would keep RF from traveling down the shield of the coax. I wondered about this since my friend on his trip to the old mining town in California did not have a counter poise and had no issue with RF on his coax. Possibly the ground itself under the antenna served this purpose. I also read that a capacitor across the primary probably helped with the reactance of the match and made it possible for multiband operation without a tuner. Another revelation was that common mode chokes tend to detune the transformer and raise the feedline impedance so better to not use them. A transformer with a 2:14 (calculates “rf” to 1:49) ratio seemed to be the default model to match the high impedance of the end fed load letting high currents enter the wire and terminating with high voltages at the end. Antennas radiate well with accelerating currents across the wire media and it would appear the high oscillating currents feeding the end fed wire allows for excellent results.
Since I wanted an antenna on 80 meters (and 40 meters) I decided the wire length should be 40 meters long, or half a wavelength on 80 meters – around 135 feet. I modeled my design to see how it would perform. My 4NEC2 manual noted that modeling end fed antennas might be redundant as most of the algorithms in the software were designed to work like dipoles. Just the same I tried it out and the results seem to be more in line with the antenna’s performance. I have a very tall nearby pine tree that would serve as the high point for the end of the wire. I used 75 feet as on the “Z” axis and got the following results on 40M and 80M.


While not entirely representative because of the manual warning the two printouts looked reasonably accurate. The gain indicates approximately 3.4 dbi for both 40 and 80 meters (40 meter printout is on the left) and the patterns indicate good radiation outputs. With the potential of a good performing antenna for 80 and 40 meters I decided to go forward with the project. The key element was the transformer. I found a informative video on YouTube that detailed the assembly of a transformer that could handle a lot of power ( https://www.youtube.com/watch?v=4ceZNjM-7g4). Steve Ellington’s very well documented description is very thorough and easy to follow.
Following directions on the video I used three ferrite toroids as recommended for higher power inputs. I purchased them from Digi-Key (part no. 1934-1592-ND) for a total of about $19 and change. These were made with 43 material – Steve’s recommendation. He later published a note indicating 53 material would work better. I glued the three toroids together and wound the transformer following his directions with 14 gauge magnet wire I had in my parts bin going with the 2:14 ratio. I used a combination of 10kv capacitors in parallel that combined to net out at 100 pf, and placed them across the feed line to ground. If you plan on using the antenna on the higher bands – 20 meters and up – taking off a turn on the secondary will likely lower the SWR. My first effort had to be rewired as I failed to count the bifilar windings as part of the 14 turn secondary. Once I got it put together I used electrical tape to secure the windings tighter around the cores. I purchased a plastic box at Home Depot electrical section to use for the waterproof enclosure.

The lugs on the right are fed to the antenna and ground – the left to the coax (PL259) and ground.
The box had no outlet for allowing air to cool the core so I drilled a 1/2” hole in the side and covered with a porous cloth material. The next step was to cut 134 feet of antenna wire. I had a 500 foot spool of insulated number 16 copper wire I had purchased from Home Depot. I remembered that their electrical section has a re-winder with a footage counter attached. I drove over and asked the “electrical” area manager if he would wind off 136 feet – which he did. I now had everything I needed for the antenna.
Getting the end to the top of the pine tree was a challenge – at least 80+ feet up. One of my friends sent me an article on a PVC launcher that appeared in a back issue of QST. After reading it I headed over to Home Depot and found a willing attendant that helped me put together the pieces I would need. The four units consisted of a reservoir for compressed air, a ball valve to act as the trigger, a barrel to guide the projectile, and the latter. The result was a somewhat gangling device. Together the pieces cost about $12. I used the larger diameter piece for the reservoir coupled to the ball valve and a reducer to the barrel. The projectile shown on the left of the picture below fits into the barrel in such a manner to slide easily up and down. I placed a bolt in the top of the projectile to hold the fishing line. I assembled it using PVC glue and “plumbers thread seal tape”. At the end of the reservoir I inserted a bicycle valve using a “Schrader” stem. The cap ends of the projectile had to be ground down so they would fit in the barrel and would move up and down easily. I filled the projectile with sand (partially) so it would have enough weight to fall down on the back side. It was ready to test so I pressured it up to 60 lbs. and fired the projectile to see how it would work. It performed okay so I tied on the fishing line (20lb) and laid out about 80 feet on the ground. When I aimed it at the top of the pine tree and fired it off to witness it falling short. I then increased the pressure to 100 lbs. (probably the maximum safe level). This time the projectile flew over the top of the tree and fell down the other side. When I hooked up the end of the antenna to the fishing line it broke when I tried to haul it up. I started all over but with stranded 100 lb. test line. This time I was able to get the end of the antenna up to the top of the tree (75-80 foot level) and hauled it up.
If you go to Home Depot or Lowes when traffic is minimal the PVC section manager can help you with the pieces needed.
Lowes’ dimensions are based on inside diameters while Home Depots’ are outside dimensions.
I used 1 ½ inch pvc for the reservoir capped with threads to connect with the ball valve, and 1 inch material for the barrel. The projectile was made with ¾ inch pvc. The bicycle valve was installed on the end (secured with grommets to hold the pressure). The caps on the projectile needed to be ground down to fit into the barrel allowing the projectile to slide easily.
The air reservoir doesn’t need to be as long as the one I used. Pressure is the main propellant and will work on a smaller length of PVC.
Hooking up the antenna at the feed point was routine, and it ended up about 130 feet from the shack. With my antenna analyzer I was able to cut the wire to resonance at about 7.200 Mhz. Fortunately I had laid out about 140 feet of LMR400 five years ago to feed a 20 meter vertical (no longer used and later sold). The coax was still in the ground near the feed point. I checked it for continuity and loss and it measured –0.7db, not bad for this length. I hooked it up to the transformer and tested for SWR in the shack – everything looked good.
I was still concerned about the need for a counterpoise to avoid the coax shield picking up RF. I decided on installing a grounding rod next to the feed point. I was able to drive one into the ground next to the transformer and wired it to the ground terminal. I connected the output lugs to the antenna and it was ready to go. A final SWR test indicated 1.3:1 on 40 and 1:1 on 80 – very acceptable! Back in the shack I hooked up the LMR 400 to my Kenwood 590SG and made my first connection on 75 meters – barefoot. My contact reported a strong 5/7 from a station near Salt Lake UT. Later I changed over to 40 meters with good results on a second short QSO. I fired up my Kenwood amplifier set to put out about one KW and it loaded perfectly. I use the antenna almost daily at this output – no tuner needed on either band allowing for a quick swap with minimal adjustments on the amp. The performance has been outstanding and seems to mirror the 4NEC2 readout. What fun to have a Zep excellent performing antenna. This might be a great solution for those living HOA restricted areas since the wire can be hidden from the naked eye.
Can you find “Waldo’s” Stealth Antenna?
PS I gave the launcher to a ham friend, N2GG – Gil, out of New Mexico. I asked Gil to “pay it forward” to other hams that would need it to launch. He promised to loan it out.
| W9YW | 2021-04-21 | |
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| My End Fed Stealth Antenna | ||
| Maple Leaf Studios supplied me with his EFHW 49:1 and over the years, I've modified it. I have a handy 85ft sycamore tree in one corner of my lot, and put the other end atop a Rohn 40' pole. The height, which slopes from roughly 80ft in the tree to the top of the Rohn steel push-up pole at 40ft, gives me an incredible signal-- even on 6M and horizontally polarized 2M! The length is now an inverted-L half-wave on 80M. Unlike others, I'm not using a 1:1 balun as I don't have problems with RF inside the "shack". There's a 100ft of low-loss counterpoise-acting coax and it all works like a charm. On this limited lot size, it's the best that can be done, which is pretty powerful! | ||
| W4VR | 2021-04-18 | |
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| My End Fed Stealth Antenna | ||
| good article Tom. Ron, W4VR | ||
| KT4EP | 2021-04-09 | |
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| Re: My End Fed Stealth Antenna | ||
| Close to mine - I have 160 feet of wire, fed with 6 feet of RG213 to an LDG 4:1 with several random length radials and a ground rod hooked up to the other side. Was looking at a commercial end fed but decided to purchase 500 feet of wire from DX Engineering to make simple run of wire and not have to splice anything. Also have a 6 loop coil of coax before the 4:1. Works great 160 to 6 meters. Reply to a comment by : K2JVI on 2021-04-06 Nice work-my current HF antenna is similar to that the difference is I use a DX engineering 4:1 current balun and added about 60 ground radials in all directions. I have two wires, one at 120' long and one at 60' long which I select with a relay. Basically I bought part of the dx engineering 43' all band antenna sans the 43' pole. I feed it with rg213 and run 600 watts to it with no problem, works well from 160-15 meters. | ||
| K2JVI | 2021-04-06 | |
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| My End Fed Stealth Antenna | ||
| Nice work-my current HF antenna is similar to that the difference is I use a DX engineering 4:1 current balun and added about 60 ground radials in all directions. I have two wires, one at 120' long and one at 60' long which I select with a relay. Basically I bought part of the dx engineering 43' all band antenna sans the 43' pole. I feed it with rg213 and run 600 watts to it with no problem, works well from 160-15 meters. | ||
| K6CRC | 2021-04-06 | |
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| My End Fed Stealth Antenna | ||
| Great article. I have played around whit EFs and such and found that a line isolator on the rig side of the feedline really helps. Otherwise, RFI tended to shut down rig and sometimes computer stuff. A few turns of coax around a toroid worked for me. | ||
| K7OFG | 2021-04-06 | |
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| My End Fed Stealth Antenna | ||
| Great article, thanks. I use an EFHW antenna for my portable use and find it a great antenna. I'm a slingshot guy for getting antennas into trees when portable and not carrying my push-up mast. But will look into your system when I'm out in my RV. As long as you have a good length of coax (I use 25ft) the RF dissipates on the shield. A short length of wire for a counterpoise/ground is recommended by Balun Designs for use with their ununs so not to have to use the coax shield. The EFHW antenna is a very good antenna and performs as well as a dipole and is multi-band without a tuner. P.S. I lived in Placerville, CA for almost 20 years. 73, Steve, k7ofg. | ||
| KJ4DGE | 2021-04-05 | |
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| My End Fed Stealth Antenna | ||
| Excellent article and details/photos. Just goes to show what enjoyment creating a working project is when you build something yourself. Good deal! I too would have reservations with a home brew line shooter, but I live right next to commercial properties and parking lots so don't want to draw a lot of attention. KJ4DGE | ||
| KT4EP | 2021-04-04 | |
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| My End Fed Stealth Antenna | ||
| Good job! and nice article. My end fed works 160 to 6 meters and is about 200 feet long. Usually as good if not better as my Hustler 4BTV on the same bands. | ||
| VE3CUI | 2021-04-04 | |
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| My End Fed Stealth Antenna | ||
| Neat article, Tom...! About the ONLY thing that might give ME reservations here is that launcher --- I'd be afraid that it might blow-up on me...! I use a ZEBCO-33 spin-cast fishing rod & reel to launch a 9-volt battery attached to a buzzer --- flies really well after a coupla tries, & the counterweight is easy to find in the brush afterward, thanks to the buzzer. To each his own, I guess... Anyway, surely an inspiring piece. Thanks for posting...! | ||