6' High 40m EFHW Real World SHTF Antenna - Concept & Intro

I felt like I never gave the ‘low 40m EFHW’ antenna concept a fair chance.
Here's an example of a recent QSO using a 20m 6' high dipole: • Working Texas with a 6...
Wire element: ~55' long? I'll measure it after testing
Height AGL: 6 feet
UNUN: Multi-tap
Tap used: 81:1
SWR: 1.0:1
Power: ~5.5 watts RMS
Yes, I worked a few DX contacts with it - including to the Czech Republic. Hey, I must brag while I can! The performance of a wire two feet above the ground is miserable of course. I wasn’t seriously thinking of using it for anything other than screwing around. Same thing with the ‘Variant 9’ version. And my ‘deck antenna’? That is serious boredom in action. Just doin’ my job, man… just doin’ my job (screwing around).
But today I thought to myself “No - the testing isn’t complete or even fair. I must see what a real world SHTF antenna might look like.. what it might act like.. who it can talk to RELIABLY...”
Let’s find out.
First contact to follow (I hope!)
73

[@jeff-73]

This is great. You always go against the grain it seems and get amazing results. More than that, your videos demonstrate the true spirit of ham radio where you're not trying to push products to buy. Your multi tap transformer hurts my brain trying to figure out how to wind my own but I'm going to try, thanks to you. Please keep making videos like these. 73

[@consciousness1237]

Something else to try, I used a 40m full wave loop at. 7 ft on plastic fence post. I fed it directly with 100 ft of RG8X no balun or anything cut for 7.0 and it was 1.1 to 1.6 on 10- 20- 40 and 6 meters. It was a horizontal lay out but gives you vertical polarization like an omni. 700 qso's in 3 months world wide in 2018 . I will allways have one now. Give it a try it's very easy and you have room. :)

[@n8nkqrp595]

That is awesome what you built with that low loop. Thank you for sharing! Believe me, it will be my next test antenna. If I show it to anyone I'll be sure to mention who gave me the idea. Sounds like fun. Take care OM

[@twohandsandaradio]

Something I want to try for a real covert SHTF antenna... Drop the 40m wire from 6 foot to right on the ground. My guess is it won't work good but it would work. I had this configuration at my apartment. About 6 or 7 foot in the air, straight out because you only have a couple of minutes notice that the landlord was coming by and it had to disappear. Fun stuff.

[@rufus4779]

looking good I live in a HOA restrictive zone. I've been running a EFHW on my 6' wooden fence covering 80-10 meters with barefoot 10-100 watts. SWR runs between 3-5 on 80m and 1.4 - 2.1 on 40 - 10 meters. I've hit most of CONUS, most of South America, some of Europe & occasional Korea and Japan. 49:1 unun and ~67' of 14 awg electrical wire. all home brewed.

[@oncydium]

I love videos like this - it's real amateur radio to me. Thank you for sharing! 73 DE KC9MAQ

[@n8nkqrp595]

Thank you! It's given me something fun to do while adjusting.. or trying to adjust to retirement. I have a million interests and hobbies but never foresaw that my entire family would be at the peak of their own family's life and their kids.. that kind of thing. Plus with the added crazy stuff happening.. it's kept me from going nuts. lol. 73 OM

[@mortimersnerd801]

... the height above ground determines if it's a cloud warming NVIS or more of a DX antenna with a lower radiation angle... you can make a choice here. The emergency preparedness angle kinda dictates NVIS be preferred with signals out maybe 350 miles, what 80 and 40 NVIS do best at. With low antennas capacitive coupling to ground increases dropping your resonate point a tad but the basic characteristics of an EFHW remain. There are some magic heights.. for 40M 16' comes to mind.... and if you really want NVIS performance, a piece of wire 1/2 wavelength and a bit long, laying on the ground directly under the antenna really soups things up...What you'll have made is a sort of end fed 2 element beam for 40 pointing straight up. Those clouds will glow with your RF..... Richard VA7AA

[@KX4UL]

Excellent experiment! My curiosity is very high when it comes to antenna length, height, UnUn applications and resulting SWR and impedance on various frequencies. Thanks SO much for posting your findings. I could watch this stuff all day!

[@n8nkqrp595]

Thank you for this comment. I really, REALLY needed it. One minute ago, I was called the problem with ham radio by Wheeler 79. He said this: " It’s people like you that are chasing off new Hams, Instead of complaining about what People are doing wrong try educating them as to the proper etiquette. Quite possibility they are doing this stuff because they are green and haven’t learned yet?" Thank you KX4UL.. take care and have a nice day Sir :)

[@Johnyrocket70]

You built a NVIS antennas. Great for talking to local people

[@procrusteus]

Would there be any point in using an antenna analyzer on an end-fed non resonant random wire to fine tune the length and select the best un-un ratio? I am using an 84.5 ft length with a 9-1 unun and then feeding that with a very short length of coax (with an RF choke located near the transceiver end) to the internal antenna tuner on my KX3. I can get a 1-1 match from 80 to 6 meters. Would the performance be any better (maybe less insertion loss with the best un-un ratio) if every aspect of the system was optimized using an antenna tuner, or would the improvements be so negligable that it wouldn't be worth the bother? The reason I am asking is that I am thinking about the purchase of a NanoVNA and was wondering if it would be worthwhile if all I will be using is various lengths of random wires in conjunction with an antenna tuner. Thank you!

[@n8nkqrp595]

Very VERY good questions. It's late but i did a screen cap on my phone so i wouldn't lose the comment and your great questions. I'll reply again tomorrow :]

[@mumi009]

Good NVIS

[@DK5ONV]

Merry Christmas and keep up good work, sir. I really like what I see there. Stay safe & hope to talk to you on the Bands. 73's de Uncle Günter

[@consciousness1237]

One other thing due to low height you do not need a 4 to 1 balun unless you have it up higher also all contacts were 10 to 15 watts. AA4CP Chuck Port Salerno , FL

[@n8nkqrp595]

I expected to have to use a strange tap on my UNUN, but found little difference in going from a normal height to something like 6 feet. I use a multi tap unun, and honestly can't remember what Z ratio tap I used on the 40m wire. It's laying on the grass right now. lol. But with my 20m efhw test wire that's up right now, I can use either the 49:1 tap or the 64:1 tap and get a nice near-unity match. 73

[@NitinVarmaManthena]

Hi N8NK QRP, How do you increase or decrease the wattage that antenna can handle? For example if I want to make an QRP antenna that works from 5 watt to 100 watt are the changes that I need to make? Basically what sets the wattage that can be used on an antenna.

[@MauriatOttolink]

It's NOT distributed inductance...It's LUMPED inductance. Distributed inductance is in the length off the wire. I haven't listened any further yet but can we rely on anything after this point!

[@n8nkqrp595]

I agree but I disagree. It is lumped inductance but you misunderstand me or I speak my thoughts poorly. The inductane is 'distributed around the core' in the sense that the more turns added (the higher the Z ratio tap used), the more L is introduced in series with the antenna wire. You are taking my use of the term in a different context than I am using it to describe my thoughts. Take this for what it is... the ramblings of a retired biomedical engineer, not an RF engineer.. just a bored hobbyist. 73

[@MauriatOttolink]

@@n8nkqrp595 Sorry for my hasty response and I must have misunderstood you. Please correct my own typo error of "OFF" for "OF".

[@robertlundstrom8061]

So what result did the 64:1 give?

[@n8nkqrp595]

Oh boy, I don't know. Let me look at the video again and I'll get back to you. If I have to, I'll put the wire up again and do some more testing on it, including contacts. 73 OM :)

[@Ei2iP]

Great job ..

[@n8nkqrp595]

Thanks! My little antenna experiments are getting strange. lol. Wait till I show what I've been finding.. just by simply running this wire antenna in parallel with my vertical. It does seem to show an intense directivity straigt to the SW from my home in Michigan. After I'm done posting the UNUN wind vids (there will be 2, the first most likely tonight) I'll get to work making contacts on these 6' high wires. I think that's a pretty good approimation of a super compromise antenna if need be. Take care OM