DIY HOMEMADE DUAL BAND VHF & UHF (2 Meter & 70 Centimeter) TUNEABLE ANTENNA

[Sheepdog777]

Hello Fellow Hams and Radio Enthusiasts,

Hope everyone is doing well and enjoying the approaching Spring. Hopefully, this will be one of the last cold days for Missouri this year… Let’s See What Happens.

I know there is eleventy thousand Prefabricated Dual Band VHF/UHF Antennas out there, but if you want to make your own with 100% tunable capability for both bands on the cheap then this post is for you.

Bit of an Antenna freak, even as a new Ham, and wasn’t satisfied with many of the responses I’d come across the internets of, “you cannot make a dual band VHF/UHF antenna worth anything yourself, go buy some Chinese product” and/or a version consisting of less than 5-Steps. Basically, a simple elegant solution, is what I’d come across with a direct coax transmission line feed w/ NO BALUN. I paid $8 for a 6-foot 3/8” stainless steel rod from Ace Hardware with the rest of the materials from already acquired items.

The credit for these two versions of the same basic vertically polarized dipole antenna goes to Dave, KG0ZZ for the first video and Paul Faulkie (Faulkner), M0PCF for the second.

Dave, KG0ZZ ZED ZED’s Version (For the this and the portable version’s mounts, get creative!)

PARTS LIST

All stainless-steel element mounting hardware. Use larger size hardware if flat washers do not extend across both sides of the antenna element.

• 2 each 1/8" Stainless steel rod, 3' (.9 m) long.
• Acrylic Plexiglass, 18" x 2-1/2" x 1/4" (45.7 cm x 6.4 cm x 7 mm).
• 2 each #6 x 32 x 1" (25 mm) Machine screws.
• 2 each #6 x 32 Wing nuts.
• 4 each #6 Large flat washers.
• 2 each #6 Split lock washers.
• 2 each #6 External tooth lock washers.
• 2 each #6 Crimp-on ring connectors.
• Mast mount clamp.
• Plastic cable tie or small U-bolt.

NOTE: The MOST CRITICAL part of making this antenna is the exact measurements of the U-Shaped Dipole Elements. Pictures Embeded/Attached.




MEASUREMENTS:

3/8 Inch Diameter Stainless Steel Rod – 6 Foot Length or 2x 3 Foot Lengths

2M – VHF Element Length (From Outermost Edge of Bend)
18 5/8 In / 47.3 Cm

70 CM – UHF Element Length (From Outermost Edge of Bend)
6 1/4 In / 15.9 Cm

Original Version // Dave KG0ZZ

A Simple 2m/70cm Vertical Dipole Antenna

Portable Version // Paul M0PCF

73’s
Ryan, AE0TO
o7

 

[dave3825]

You should add that to the Homebrew antenna section in the Wiki. Can you link the calculator you used to obtain the measurements? Might be fun to make one for different bands.

Scanner Antennas - The RadioReference Wiki

wiki.radioreference.com

 

[nd5y]

Those work ok on 2 m but on 70 cm the radiation pattern is terrible.
The YT clowns have probably never heard of antenna modeling.

A better design is to make a 2 m dipole with one (or two) closely spaced (about 1 inch) 70 cm 1/2 wave parasitic element (also called coupled resonator).

https://www.qsl.net/dk7zb/Duoband/open-sleeve.htm

 

[Sheepdog777]

You should add that to the Homebrew antenna section in the Wiki. Can you link the calculator you used to obtain the measurements? Might be fun to make one for different bands.

Scanner Antennas - The RadioReference Wiki

wiki.radioreference.com

I didn't know that I could edit the Wiki Page. I'm a newer member so figured I'm under the probationary period. I didn't use a calculator for these. The measurements work and confirmed mine with a NanoVNA. Works great on both bands.

 

[dave3825]

If you know how to edit a wiki, have at it. Anyone can. Just choose preview before making any changes

 

[prcguy]

Those work ok on 2 m but on 70 cm the radiation pattern is terrible.
The YT clowns have probably never heard of antenna modeling.

A better design is to make a 2 m dipole with one (or two) closely spaced (about 1 inch) 70 cm 1/2 wave parasitic element (also called coupled resonator).

https://www.qsl.net/dk7zb/Duoband/open-sleeve.htm

I sort of agree with this post. A 2m dipole by itself will also be resonant at 70cm with a good match but the radiation pattern will be wonky putting much of the energy above and below the horizon. Some designers think they can add a resonant 70cm element to fix it but what really happens is you now have two resonant elements on 70cm, both low impedance and they load the feedpoint down below 50 ohms and RF currents simply divide between the two elements.

The end result probably fills in at the horizon some on 70cm but it’s not the best way to make a dual band antenna unless the two bands are not odd harmonic related.

 

[Sheepdog777]

Those work ok on 2 m but on 70 cm the radiation pattern is terrible.
The YT clowns have probably never heard of antenna modeling.

A better design is to make a 2 m dipole with a closely spaced (about 1 inch) 70 cm 1/2 wave parasitic element.

Huh... YT Clowns... Perhaps. Both gentlemen I witnessed were 100% genuine and forthright. I believe the first one, Dave, may now be a Silent Key, since this video is from 11 years ago, 2012, and someone with a different name has the same one issued in 2013. Perhaps just a pen name...

Regardless, this seems to work for me with 1.02 & 1.04 SWR w/ 80ish db logmag on both bands... Works better than ANY prefabricated antenna I have used in my short Ham career, which is why I shared it.

Didn't use any antenna modelling software for this, because, although I do have MMANA installed on this here computer, being a dumb Arkansas Hillbilly, I don't quite have it figured out yet... lol.

I've also read on the internets that Underground Antennas don't work, yet we use them in the Military Everyday. Sometimes the Jingle Keys are for show....


I learned long ago, that there's Expectation, then there's Reality. When those two meet, it's often awkward. Like Guglielmo Marconi claiming to have invented Radio and accepting the Nobel Prize in 1909, when it was "Light Work" for Tesla in 1892 kinda awkward...

To my recollection Tesla refused the Nobel Prize and $20,000 for his electricity achievements. When he died, Uncle John Trump a physicist working on advanced electronics, radar, etc down near Roswell, NM was the "Top Man" the U.S. Government sent to "Review" his papers.

Fun Fact:
Schriever SFB, CO is located on original site of Tesla's Wireless Electricity experiment. (1899-1900)

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[Sheepdog777]

I sort of agree with this post. A 2m dipole by itself will also be resonant at 70cm with a good match but the radiation pattern will be wonky putting much of the energy above and below the horizon. Some designers think they can add a resonant 70cm element to fix it but what really happens is you now have two resonant elements on 70cm, both low impedance and they load the feedpoint down below 50 ohms and RF currents simply divide between the two elements.

The end result probably fills in at the horizon some on 70cm but it’s not the best way to make a dual band antenna unless the two bands are not odd harmonic related.

I'm no Physics Janitor, but at 45 ft AGL, with a direct feed coax, NO BALUN... I get 1.02 VHF & 1.04 UHF, 80db logmag, and 50-60 Ohms on my NanoVNA. Otherwise it's hitting repeaters from 50+ miles in my attic. I do need to move it to hit my favorite repeaters, however. Just my experience with the one I built, but then I didn't use Antenna Modelling software for this either. I was looking for simple and elegant. Kinda like I don't need to know how build an All Band HF Radio to use or enjoy it. I guess it's way too simple to work. I must go buy some Chinese copper! Lol.

View attachment 138395

 

[prcguy]

“Works better than ANY prefabricated antenna I have used in my short Ham career, which is why I share it“. A simple dipole is a standard for comparing other antennas for gain. All your statement means is that you never had an antenna with more than 0dBd gain. And using a picture of Greta (that poor disturbed child) to make a point will only distance you from the crowd.

Fun fact: I’ve toured the inside of Schriever SFB (originally Falcon AFB), the areas where you need a high security clearance and must go through the little booth that checks your weight and does a retina scan that must match your badge.



Oh what I would pay just to be able to give Greta one good hard smack!

 

[Sheepdog777]

If you know how to edit a wiki, have at it. Anyone can. Just choose preview before making any changes

I personally, don't touch Wiki with a Vaccinated Crowbar, but then I also don't go to Snopes and say, "My Research is Complete"....

I appreciate the information, however!

View attachment 138397

 

[Sheepdog777]

“Works better than ANY prefabricated antenna I have used in my short Ham career, which is why I share it“. A simple dipole is a standard for comparing other antennas for gain. All your statement means is that you never had an antenna with more than 0dBd gain. And using a picture of Greta (that poor disturbed child) to make a point will only distance you from the crowd.












Oh what I would pay just to be able to give Greta one good hard smack!

#METOO on the Greta Smack. As an Antiterrorism Professional for several decades, I've learned that being away from the "Crowd" isn't always a bad thing. I've done my share of Reconnaissance, so usually on the next hill or grid square anyways....



As an Amateur Extra passing all three tests on my first attempt, I know that I am really just Extra Amateur...

But for the purposes of this post and my first attempt at a homemade antenna of this type, I could care less about the Nth Degree speculation of it's radiation pattern, I was looking for simple and practical. Isn't everything a compromise in radio and life anyways?

Does it work for me? Yes! Did I need a Harvard or MIT Degree to make it? No! Lol.

 

[nd5y]

I sort of agree with this post. A 2m dipole by itself will also be resonant at 70cm with a good match but the radiation pattern will be wonky putting much of the energy above and below the horizon. Some designers think they can add a resonant 70cm element to fix it but what really happens is you now have two resonant elements on 70cm, both low impedance and they load the feedpoint down below 50 ohms and RF currents simply divide between the two elements.

The end result probably fills in at the horizon some on 70cm but it’s not the best way to make a dual band antenna unless the two bands are not odd harmonic related.

I built a couple of these out of 12 ga. wire with two 70 cm resonators and one out of 1" tape measure with one resonator. It appeared to me that adjusting the spacing can get the imedance on 70 cm real close to 50 ohms. I have no way to measure the radiation pattern. All I can do is model with MMANA-GAL and that doesn't take into account the coax and not having a balun or choke.

I made a smaller one for 800 MHz. It seemed to receive at least as well as a center fed EDZ.

 

[nd5y]

Both gentlemen I witnessed were 100% genuine and forthright.

You mean like Greta? Be careful with trying to learn about radio from YouTube. The majority of those people don't know very much.

 

[Sheepdog777]

I built a couple of these out of 12 ga. wire with two 70 cm resonators and one out of 1" tape measure with one resonator. It appeared to me that adjusting the spacing can get the imedance on 70 cm real close to 50 ohms. I have no way to measure the radiation pattern. All I can do is model with MMANA-GAL and that doesn't take into account the coax and not having a balun or choke.

I made a smaller one for 800 MHz. It seemed to receive at least as well as a center fed EDZ.

Ok, that makes sense to me with the 12ga wire... I originally used 15-20 ft of 75 Ohm Video coax (what I had), and got the above stats. I got curious about a speaker wire feed, 16 ga, and it all went off the rails. The direct feed, center conductor to one element and braid to the other is what works the best... that I've found thus far. Ohms are about 50-60 depending on where I'm standing while reading the VNA, not touching it. I also have Public Safety tower transmitting near 2M less than a block away which likes to wig out my readings when they're TXing. But as a baseline it works fine for my purposes.

I love the MMANA software but I really need to pony up a learn it properly... I load the prebuilt antennas and slightly alter them. Again, with that level of antenna building I'm an aspiring Padawan...

 

[Sheepdog777]

You mean like Greta? Be careful with trying to learn about radio from YouTube. The majority of those people don't know very much.

It's a Meme...

I learn from wherever I can. Then I test it. Then I make a judgement. Having trained tens of thousands of people in combat skills, it's the way to go. I let the self-licking ice-cream cones sit in their Ivory Towers of judgement.

View attachment 138405

 

[prcguy]

You also have to consider many online antenna projects are not what they are advertised to be. Here is one example that will waste your time, it’s not even considered an antenna of any useful kind but if you read the comments the author has duped a lot of people.

I’m also not saying the OP of this thread was duped but wild claims can mislead other readers into thinking something is better than it actually is.

 

[Sheepdog777]

You also have to consider many online antenna projects are not what they are advertised to be. Here is one example that will waste your time, it’s not even considered an antenna of any useful kind but if you read the comments the author has duped a lot of people.

I’m also not saying the OP of this thread was duped but wild claims can mislead other readers into thinking something is better than it actually is.

So... um... what you're saying is I am making wild claims? Gee... I must have stock via Blackrock and/or Vanguard in the stainless steel markets to dupe people out of $8 rods a piece from Ace Hardware...
View attachment 138432

All kidding aside... I gotcha on the video you posted! I watched that one waaaay back and laughed. The old micro–Yagi NSA Decryption Antenna sucks you in every time! WOO HOO! I also heard it unlocks Hulu, Netflix, Amazon Fire and Apple TV as well as refills your Turn Signal Bluid on your bicycle... I might be from the Hills of Arkansas, and after retiring from the U.S. Air Force feel reasonably intelligent enough to figure out the internet, still trying to figure out how to tie them thar shoes tho... Prolly a Shill DIY YooToob video for dat sum where...

You can literally try this with a metal coat hanger and scrap coax, but this might break the bank for some folks. After the sheer negative responses saying, "IT WON'T WORK!!!", when most clearly didn't read the original post, much less actually watch the videos, I am beginning to see why Ham Radio is slowly dying on the vine. Some new guy chimes in and it's off to the races! My personal Motto is A Posse Ad Esse, and spent many a 16-hour shift guarding things in hangars that were considered "Impossible".

Bottom Line, I tried it and it works amazingly well. Better than I thought. If you don't believe me, BUILD IT. One of the best things about this too simple to work design is it is very forgiving and allows you to tune it by simply adjusting the elements, by loosening the wingnuts. I followed the direction precisely, especially the lengths. I didn't have to fiddle with the adjustment part and got the aforementioned results.

I am also beginning to see why some Hams have entire rooms filled with radios, when I can match 100% of their overall capabilities with less than $2000. To each their own, but I don't see spending much more than that, ESPECIALLY if this is the type of folks on the other end of the wireless circuit!!! Seems they're sitting under the bridge, just waiting to Hijack someone.
View attachment 138437

I razz the negative responses a little bit, because I spent a career in a monolithic bureaucracy, filled with PhDs and huge brains giving a million reasons to not be able to do something, especially in Washington D.C. and the U.S. Air Force Academy. Then, to be proven wrong by some "New Guy" who cut through the Gordian Knot of crystallized dogma to prove them all wrong. Reminds me of the Archeologists who are dumbfounded by the ancients who created perfectly circular structures, when they didn't know about Pi π (3.14~) They never think about them using string and their fingers...

Much less, they clearly haven't read their Plato, which covers Advanced Cosmology, Spherical Earth, Celestial/Orbital Mechanics, and Quantum Bayesianism (QBism) to name a few 2,500 years ago. Intelligence isn't the capability to recall rote memorization of facts not acquisitioned personally, it's being presented with new information and solving problems or circumstances. PROTIP: The Key to Unlocking the Universe is Analogy.

So, for all the critique shrieking of "It doesn't work!" They don't do the one thing, which should be so clear, to confirm whether it works or not... Build it!
View attachment 138434

 

[AK9R]

Folks, if you are going to talk about environmental activists or political figures, then this thread will be locked. If you are going to talk about antennas for amateur radio, have at it.

 

[Sheepdog777]

To the Common Ham/Person,

Ever feel like your 100% Over Target, simply because you get immediately Hijacked by Group-Think?

If you’re like me, who feels the PTT button is the best confirmation of whether an antenna works or not, then feel free to try this concept 100% free with 2 metal coat hangers. If it works, then please provide your experiences here, if you like. What I find highly interesting is that the immediate negative responses pile up, when they clearly didn’t even read, nor watch the two videos on my original post.

Not one of them provide a solid reason or proof that this doesn’t work as well as I have personally experienced with this design. What they do is build a strawman totally unrelated to the original post then attack it as if it’s part of it, not providing any other solution than the status quo.

As a new Ham there’s all sorts of resources for building HF Antennas, and some single-band versions for either VHF and UHF. But I had to dig to find these two particular sources. So obscure in fact than when I directly searched for this concept, I couldn’t find it. I actually found these looking for something else and they showed up on the periphery.

Since most of the overall Ham bands were chosen specifically based of the principle of Harmonics, yet not immediately being able to find anything solid regarding a DIY VHF/UHF Dual Band Antenna, I internally thought, well this is B.S. There must be a simple way to make a Fan-Dipole equivalent for VHF/UHF. Once I found these two versions of the same design, they made 100% sense to my understanding of the principles behind radio. Perhaps it was tinctured with a little confirmation bias, because I was actively looking for this very thing.

As with everything in Ham Radio and life in general, it’s a compromise. Yet, with this simple design they both have great SWR, Logmag, Tx/Rx capability, coupled with extremely simple construction steps, all with the noted characteristics in my OP. No wild claims, no Ridiculous B.S., it simply works better than any of my prefabricated VHF/UHF antennas, be they ICOM, Diamond, HYS, Comet, Nagoya… I guess some folks don’t want you to experiment and find low-cost or no-cost solutions. For anyone taking Economics 101, the #1 Principle underlying the entire scheme is the Principle of Scarcity. Convince people they “Need” something, then convince them that you’re the only Seller of the item. Most of the entire Services Industry comprises services people can to do themselves, but the trick is to spin folks in enough circles so that they don’t do it themselves and pay someone else to do it. Reminds me of the Professional Weight Guesser on The Jerk...

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The most ridiculous part is the actual negative responses themselves, almost as if they own stock in some Dual Band Antenna Manufacturer at worst, and perhaps not wanting folks testing this Homebrewed Antenna on their Repeaters at best. Regardless, what they do accomplish is 100% distraction / detract from the Experimental Spirit of Radio.


The very first negative response comes from someone who snipes everyone of my posts on QRZ, again never responding to the content, just scattershot negativity. In this thread he provides an “alternative” that states at the very end of the article, “The diameter and distance of all elements is very critical, a little difference causes severe changes in the parameters!”

– Seems Almost like Sabotage – I'm sure it's not. As the Antenna Design, I posted is 100% Mechanically Tunable and Very Forgiving. I only stressed abiding by the exact measurements provided during the construction only because it’s smart to follow directions and abiding by said instructions… I didn’t even have to tune or adjust the antenna. Don't take my word for it. Test it for yourself free with available materials or below the fraction of the cost of a cheap Base Station VHF/UHF Dual Band Antenna. That's all I wanted to share or discuss.

 

[Sheepdog777]

Folks, if you are going to talk about environmental activists or political figures, then this thread will be locked. If you are going to talk about antennas for amateur radio, have at it.

Could care less about less than 1% of this thread peripherally referring to either of these topics. I'd rather talk constructively about the subject of my OP rather than myopic strawman arguments. Please and Thank You.

Ryan, AE0TO
o7