Explaining End Fed Half Wave Antennas & Experimentation
Вставка
- Опубліковано 6 лип 2024
- This presentation explaining the basics of End Fed Half Wave (EFHW) antennas was done at the REAST DATV experimenters night hosted by Justin VK7TW and Hayden VK7HH. Topics covered were the basics of EFHW antennas by Steve Yates AA5TB including lengths, design and installation of the antenna. Voltage and current distribution and the issues this presents, the minimum counterpoise, impedances and turns ratios of end fed impedance transformers.
Hayden VK7HH then took the audience through a great presentation on his experiments with his EFHW. Hayden covered the modification based on the VK4YE design, the testing, and the additional 80m loading coil, the coax counterpoise, and the common mode toroids. This allows a antenna for smaller spaces.
Toroids 👉 geni.us/zl6H
FT-240-31 👉 geni.us/tLvfMqw (Amazon)
FT140-31 👉 geni.us/ps6to (Amazon)
Some links are affiliate and I may receive a small commission on sales
► $15 OFF at Radioddity: radioddity.refr.cc/haydenvk7hh
References:
Steve Yates - AA5TB
www.aa5tb.com/efha.html
www.aa5tb.com/efha_wrk.html
www.aa5tb.com/coupler.html
Ben - VK7BEN
www.vk7ben.id.au/2017/01/09/e...
VK4YE
sarc.org.au/wp-content/uploads...
Steve Dick - K1RF (The End Fed Half Wave Antenna)
gnarc.org/wp-content/uploads/T...
reast.asn.au/
⏱️TIMESTAMPS⏱️
0:00 End Fed Half Wave Fundementals
0:43 Voltage and Current Distributions
2:32 What are End Fed Half Wave Antennas?
4:01 Counterpoise or no Counterpoise
7:06 Son of Counterpoise
8:24 How to Make a EFHW Work - Tuning
10:36 Coupler Learnings - Counterpoise and SWR
12:19 AA5TB Musings
13:22 Extending this to other Antennas
15:30 VK7HH Introduction - 5 Band End Fed Design by VK4YE
17:55 EFHW Layout
18:49 49 to 1 Impedance Transformer build
20:22 80 Meter Loading coil construction
21:59 Installation of the Antenna
22:50 Common Mode Current Choke
29:01 SWR Results
33:07 How many toroids should you use?
35:23 A Full Size 80m EFHW is actually a multiband antenna!
36:29 Adding 160m capability
🎥 Watch more recent videos here: / hamradiodx
Support Ham Radio DX:
► Patreon: / hamradiodx
► UA-cam Memberships: / @hamradiodx
► PayPal Tip Jar: www.paypal.com/donate?hosted_...
► Merch: hamradiodx.net/merch
► Buy Ham Radio products on Amazon & eBay: geni.us/HamRadioDX
► Gear I Recommend: www.amazon.com/shop/hamradiodx (Affiliate)
Items in My Shack:
► www.hamradiodx.net/vk7hh-shack
Follow Me:
► Website: hamradiodx.net
► Facebook: / vk7hh
► Instagram: / hamradiodx
► Twitter: / hamradiodx
► Discord: / discord
► Ham Mail: Hayden Honeywood - P.O Box 5071, Sandy Bay Tasmania 7005 Australia
#HamRadio #EFHW #EndFedHalfWaveAntenna
Music:
Bensound: www.bensound.com/royalty-free...
Epidemic Sound: www.epidemicsound.com/ - Наука та технологія
This is the BEST explanations of how an EFHW antenna system works. Thanks!
Glad it was helpful!
I've watched alot of EFHW antenna videos trying to figure out the magic, but have always come up frustrated.. This piece of work has answered all my questions, and then some! Great work and thank you!
Thanks Captain! I appreciate the comments
I loved this video -- great format, nice patient discussion, and good material. I recognized every one of the references, as I've been collecting info about these things. I'm glad I found your channel, and am subscribing now.
I run an 80m home built EFHW for the better part of this year, and have worked the world with it from Florida in the USA. Both digital and SSB, it's a fantastic antenna and a great compromise if you can't have a full blown antenna farm.
Looking forward to the show! I ❤️ EFHW antennas.
Thanks Adam!
I'm glad the whole "you don't need a counterpoise with an EFHW" nonsense has been dealt a death blow by Steve Yates. Thanks for highlighting his work.
Excellent video. So much information. Thank you.
A great video; You express it so clearly and give great information and examples. I use one of my end fed half wave antennas a bit differently. I also like to listen to other short wave bands, so Instead of using the 49:1 trans-match- and a wire cut to a specific half wave length for a specific frequency, and the harmonics that come with it, l use a base loading coil to electrically make my wire longer. I'm sure that You've made one too long and had to trim it, I make use of that length error instead. It's a 2 inch base loading coil with a value of 156 uH ( which it turns out, is at least twice too big for what I need), It's a home made coil built on a 2 "PVC pipe, and it can fit a regular 3/8th's fine threaded buddy pole type mount for a base loaded buddy pole type set up on a ham stick type mount that uses a whip. One end, connected at the trans-match, just has a jumper attached, and the other, coil end, is connected to the half wave length of wire. So I still get a 50 ohm impedance conversion from the half wave wire length as long as it is shorter than the wire length required to tune it to the new frequency I choose to receive. My 20 meter wire easily brings in the marine bands and the aero bands which are lower than 7 MHz now. And if I check it with my antenna analyzer, I find I can easily bring it close to a 1:1 SWR match for any of those frequencies too. But as a listener, I am not transmitting. It works so well, I am using my shop's rain gutter as a tunable shortwave antenna since the coil's location is so close to the end of my rain gutter. And it can also tune the ham bands as well for QRP work. And I only need to adjust the jumper.
Mine's a base loaded end fed half wave antenna now, still using the exact same 49:1 trans-match. and it can transmit well where ever I am legally allowed to transmit, or to listen clearly anywhere below that (and I can still make use of the harmonics of that new frequency as well, just like before for higher frequency coverage.) I live in an HOA controlled community, where no visible outside antennas are allowed. It works.
Great presentation, I really enjoyed it!
Thanks Harry!
Informative video. Where I am at is in my small garden I set up an inverted L antenna fed off an earth rid via a 9:1 UNUN added a choke and made a line isolator at the shack feed point. Working well on HF 80m to 10m. This week swapped the 9:1 UNUN for a 49:1. Similar low band performance Uk 10m in this set up is a great match. Keep it up guys. 73s M0 DDK.
That's something I have to say often.... "Remember what I told you? Forget it."
Great video! Thank you. I am using endfeds almost exclusively to a fair amount of ridicule but work great for me.
My sis lives in Hobart.
Dave
KI7DPP
Thanks Dave
I used a 240-31 toroid instead of a 43 mix for the 49:1 on my inverted L antenna. The coil was made to 113 micro Henries. The antenna is resonate 1:1 on 3.5, 7.0, 14.0, 21.0, 24.0 MHz. A little high on 28, but nothing the AT can’t handle. Counterpoise below ground, and antenna feed point mounted 1m above ground, and long section about 6m above ground. I’ve swapped out the 31 mix for 43 mix, SWR is much higher, and 80m >3. Put the 31 mix back and SWR was about 1:1 on all, except 10m. The moral of the story, you can use a 31 mix with good results.
great stuff! I learned a lot from this material! Thanks guys! :)
Good going here boys!
Very good video , thanks
Great presentation. TKS fer all information. I Home made fer 11 meters an end Feed 9:1 with an old ferrite From an old Tv, with 4,40 meters mounted in rod fish of 7 meters long. Works pretty well with low SWR along the band of 11 meters, driving 10 watts on it, the contacts was amazing all over the world and inside Portugal, with good signals, very low noise. That's it, TKS fer sharing all this information, keep going with your knowledge.
Thank you for the comment! Glad your antenna is working so well for you. 73!
@@HamRadioDX Yes works pretty well, I put 12 meters cable long, and tune in all bands except 11 and 16 meters, so I have to reduce to 4,40 and works very well from 26 to 30 MHz. 7351 and good contacts.
@Maverick Chester for Eleven meters I usually use 4,40 meters in rod fish of 7 meters. 7351. Attention not carbon fiber, only glass fiber.
@Maverick Chester good morning in feet is 14ft, you can put in a vertical works fine. You could see in my channel, many contacts I've made with end feed for 11 meters CB band. 7351 good contacts.
I built an EFHWA from a design in a RSGB book. The interesting part was the matching method. It used a shorted quarter wave section of coax connected to the antenna (10m of al tubing strapped to the toilet pipe over a flat steel roof). You used a needle to probe the coax to get an impedance match which you then made permanent with coax connectors. Worked a treat with DX all over on 20m. No multi-band but no matter. ex VKALR
This is very informative! Thank you!
Glad you enjoyed it!
@@HamRadioDX it has intrigued me enough to look into the End Fed antennas. I have a love for all antennas, j poles, dipoles, but I had not looked hard at the EFHW. I have made a CaHRTenna and had no clue how it worked until watching your video.
Thanks guys, very interesting
Thanks for watching
Steve Ellington has over several years found several ways to use the EFHW , one by adding a capacitor in the middle of the radiator drops the resonate point for the higher band. You should review his collection of videos from years of use and testing.
Yes I did, very interesting viewing
great Norton T-shirt!
Question: Chameleon Emcomm III shows the counterpoise length at 13 feet for the 40 meter band. So based on your initial remarks and explanation, should the counterpoise be .05 of the wavelength....which would result in the counterpoise being somewhere around 6.8'. Much shorter than they are recommending
This video is fantastic and very very helpfull. Thank you very much. 73
Glad it was helpful!
@@HamRadioDX 👍ON1JV
Good, interesting video. I`am using 1:49 unun in my LW.
does your EFHW work on 17m (18.110-18.168) in its current configuration? if not, I’m curious to know whether anyone has added a second element (fan efhw) for 17m?
Greetings, interesting call sign VK7HH, this call sign originally belonged to a friend of mine from England who lived in Tasmania, I guess the WIA re-issued it to you sometime after my friends death in 2013. I liked the presentation as am currently making the 49-1 transformer (G8AMG U.K)
Thank you. Yes I know who you are talking about. I was VK7HA up until about 2014/15 or so. Good luck with your build.
I just built my transformer. But I don’t have a way to tune it besides just adding the antenna and tuning that. Is there another method or would that be sufficient
I just got my General license and have an HF rig, a Kenwood TS-430S, and now i need an antenna. I was thinking about an end fed half wave antenna and I will have to buy an antenna tuner. 73 from K9POW(AG) in eastern Tennessee.
So, you decided that an external ground lug on the 49:1 unun was unnecessary?
I am going to be installing an 80-10 EFHW and I am struggling as to how I should run the wire. I am on the second story of my home and want to run the antenna from my roof to the 70ft apex of a tree next to my house and then down to a tree behind my backyard fence. Unfortunately this tree behind my fence is on the slope of a hill. The feed end would be East End and the tip would be West end of antenna. This hill is solid rock blocking much of my RF to the West...which is unfortunately over the Pacific even though I live close to the coast here in California. I might have to bend the tip in North direction to make it fit. This configuration gets me the most wire as high in the air as high as possible. It is possible I could run the coax and feed this thing from the tree on the slope of the hill if there was a big advantage....it would just require a much longer run of coax. Any thoughts?
do we need a common mode choke with an efhw?
Best educational video on You Tube about EFHW antenna. I live in HOA territory where I,m able to run from 40ft to 133 ft in my back yard around my house. Which balun would work the best for 80m-10m, 4:1, 9:1 or 49:1 ? Thanks, John KR6BJ
Do the primary and secondary windings on the EFHW transfomer need to be twisted together?
Yes, two turns secondary twisted with primary
Hello, great info. Having touble sourcing a 100pf high voltage capacitor, cant find at Jayco. Ebay only sell them in bulk? Cheers.
Why does only the current radiate? Because the E-Vector in the near field gets shielded or absorbed so quickly?
Well done! Subscribing plus like, thank you from 4X1PD, 73!
Greetings DE John VK4VT. Has anyone modelled what happens when the coupler is mounted on one corner of a large metal framed , steel sheeted shed and grounded to the shed frame?
Greetings could you tell me what gain have the EFHW antenna. Excellent your video
W4EDY
I notice in your schematic of the EFHW antenna a capacitor located on the secondary of the transformer, whereas almost every EFHW transformer design I now see has a compensation capacitor on the primary of the transformer and no capacitor on the secondary (I see at 19:18 in the video that the actual transformer build does have the compensation capacitor on the primary side which is typical). Just FYI, Don (wd8dsb)
What you SHOULD have done with this video, is started AT THE BEGINNING. What is an End Fed Half Wave? First example being, the ZEPP antenna. As an alternative to what you ended up doing, which was talking about the COUNTERPOISE.
It was like going to a posh banquet, and starting with desert or brandy and cigars. G7VFY
OKAY... thank YOU..
I've been trying to get one going with a 20 odd metres of antenna and 2m of wire counterpoise. Can get it to work on 40m, but so far unable to get multiband to work at all. I'm guessing I have to bite the bullet and go for coax counterpoise.
I stuck up a 40m HWEF at about 25ft inverted V. SWR according to my Nano VNA is great for 10, 15, 20 and 40. It is usable on 6, 12 and 17. 30 is no go. I have about 25ft coax going to a lightning arrestor then another 25ft ish to the shack. Did I get lucky or am I missing something?
19:14 Looks like only 13 turns (count the inside passes through center) which is actually only around 42:1. Should have 14 turns, so 14 secondary divided by 2 primary is 7, 7 squared would be 49 (49:1). Having only 13 turns is 13/2= 6.5, 6.5 squared is 42.25 so 42.25:1 ratio.
Inductors are additive in series, so you would use two in place of one, at half the induictane, would split the heat loss power?
I am glad to see EFHW explained and why instead of cut a wire this long, wind a torpid like this and solder a cap across here, and there you have it and use or don't use a counterpoise. Yes, these can work but are they efficient? AA5TB has an excellent sight for explaining what to do.
Thanks for the comments. It’s all about experimentation isn’t it!
If I start with a 40 mtr efhw and put on an 80 or 110 microhenry coil, how long do I make the short end section to get to 3.56 mhz? Is there a formula? My 40 mtr section is designed for 7.05 mhz. Thank you.
I think in the video I say how long mine was. I haven't seen a formula per se but most of what I've seen is just a few metres past the coil. You can easily measure and trim as required.
great video. however for DX there is a difference between 20 over and 40 over.
Somone was telling me that the efficiency on the harmonics goes down by 50% each time. Is this true? Every article I've read has not had any information on effective radiated power on the harmonics.
Sure sparked me, TNX!!!
73 N8AUM
What about shorty 40m antenna
For any current that flows in a radiating element, and equal current MUST flow in a counterpoise of some kind. If it has no counterpoise, it will create one...
Using 40m of wire gets you some large lobes with gain on the higher bands. If you used 80m of wire I think you can get some nice gain (over a ½wave dipole) on the 40m band.
I'm going to experiment
I plan on replacing my wire to get a 1/2 wave folded around the yard on 80m and see how it performs
@@HamRadioDX Did either of you follow up on this with 80m?
very instructive and good information 73's xe2ksl Mexico
How can something be “just a little bit more unique”?
Just tried winding a toroid and it was a mess. I had to order a roll of magnet wire to try it again.
Провод большей обмотки может состоять из двух разных проводов по диаметру. Первая половина из рекамендованного автором. А вторая половина из более тонкого. Ток в поводе меньше, напряжение больше. Нагрузка более высокоомная.
Nice video but makes the fonts big enough to read.
Superb! G1PGI
Thanks Colin!
One end fed halfsquare
Using this antenna on multiple bands is bad idea, since current distribution is good only at one band. If you want to use more power or directional arrays, you will need much better feedline decoupling. Common mode choke impedance has to be over 20 kohm. If you are using broadband chokes, you need at least 4 of them. You could use only two chokes separated by about 0.1 wavelengths. This ensures at least one choke is at point of low impedance for common mode current. I have published article on End Fed antennas in WIA - AR magazine, which tells you how to make EFHW high gain vertical arrays rated for 5 kW. You seem lo love quoting AA5TB, who most likely never worked DX with EFHW.
You might want to check out some of my other videos Tino... I've worked DX using my EFHW quite well actually. Glad you liked the video!
@@HamRadioDX Perhaps you should watch my video: ua-cam.com/video/gcW-PdvsmDM/v-deo.html .
You will see example of good EHFW antenna.
I run Eu pileup on 80M CW and my signal is S9 on S meter in Romania.
My antenna was EFHW 3 element vertical yagi.
I Can Use 40 Meters In My Yard In One Lick :D
Now Running Dipoles And Telescopic ANtennas In My Yard On Fishing Pole And In My Roof In 3 Level Of My House Tehre Is Long Wire ANtenna, 3 Meters Each Side
Drink every time you hear "yep" and you'll be utterly wasted in 5... 4... 3... 2... =P
And the problem is?
@@HamRadioDX *hiccup* no problem occifer ! ;)
A thing is either unique or not: it can't be "more unique".
"End fed half wave" is a misnomer if your using it as a multiband antenna.
Its called that because its half wave at the lowest frequency.
EFHW is easy to understand
And that is the only place it is half wave...
Norton? Another sad shadow from the past.