Dipole Antenna Showdown: Comparing Flat-Top and Inverted-V Designs
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- Опубліковано 10 жов 2024
- Dipoles for Ham Radio are the basis of almost all antennas. But what is the difference between a flat-top and an inverted V dipole? Is an Inverted V more omni-directional..? Let's take a look. Callum, M0MCX.
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Here's the video on the Vertical vs DIpole: ua-cam.com/video/ZZWzyypqqjM/v-deo.html
Great content. Maybe as possible antenna to test on software or in real life use, is an antenna originally sold by PAL Electronics in the 1960's and later by Wilson Antennas. It is right triangle loop. Its perimeter is the same as other one wave length loop antennas. It is set up in the vertical plane. The right angle is at the bottom, along with one side horizontal across the bottom. The other side to right angle is vertical with the hypotenuse at 45 degrees. PAL sold this antennas as bein vertically polarized. Wilson sold it was being both vertically and horizontally polarized when fed at the right angle. I think both were wrong and the polarization is more along 45 degrees. It worked great for DX, with signals bouncing around at all angles, but locally it seemed poor for vertical and horizontal stations. Wilson, unlike PAL, included instructions to make the antenna just horizontally polarized, by rotating it 45 degrees, with the hypotenuse horizontal and the right angle feed point at the bottom center. Users claim this orientation has better signal to noise ratio and better gain. The original had the two right angle arms of aluminum tubing and the hypotenuse of wire, but the whole thing can be constructed of wire. For the corners, I use 6 inches of antenna wire wrapped around either side of the corner insulators and solder the twists. This fixes the pull points properly. To determine the side lengths I use a right triangle calculator that only requires inputting the perimeter and one 45 degree angle. This tells me the sides I can measure from the right angle feed point and the hypotenuse is what is left of the wire. calculator here. www.calculator.net/right-triangle-calculator.html
I’m mentally challenged and thank you for making videos that I can follow, it really helps 😊
First three words of your comment.. I am same!
I didn't realize there was a big difference in the two. Have no tree in the middle of my yard to top out an Inverted V, but maybe a 30 foot pole may work. Thanks for the videos. 7️⃣3️⃣
With the center pole,You could use 5 meter fiberglass fishing rods to carry your wire dipole elements. Not much sagging! Not thicker than 14 gauge stranded thnn/thwn 2. Also will possibly allow you to rotate when needed.😮😅😊
I had an inverted V 40m with loading coils to get 80m with the center at 20ft and the ends about 4ft off the ground (had to fit the available space) for a long time. Worked great but I took it down to support the 80m end of my new Classic on the 20ft pole. Thanks for the video. Jack K5FIT
Nice
good evening Cal, we ran an inverted V back in the 70s and it worked very, it was hard for the buzy to see it.
used it for a couple of years until my parents got brave and them went up the PDL2
dave
PDL2.. Nice :)
I did a little experiment about 3 weeks ago using FT8 on 20 Meters , i found as a flat top i found i was heard in the UK , and Europe (PSK Reporter ) . When i set it as an inverted V , the FT8 went a much greater distance , Asia , USA , Africa , and Australia . This was done in 2 one hour consecutive sesions .
Interesting. PSK Reporter is a fun tool. Of course propagation can change over a couple hours depending on day/sun etc.
Thanks Cal! This answered a ton of questions I had about Dipoles
Thanks, I learned some stuff that I have always wondered about.
Glad to hear it!
Great video Callum nice work.. Inverted vee is the way for me as I will do HF portable with a mast.
Motters
M7TRS 73 👍🏻
I like the idea of short to the point vids on one subject. Get to the point and get out. Ideal for training
Balun or no balun where the legs come together, at the coax connect point? Sir, your videos are ALWAYS WORTH WATCHING, thank you.
Yes, correct.. Inside goes one-way.. the outside goes the other way.
Thankyou for the video Cal!
Inverted V all the way, less real estate required, one support needed and a better match to coax IMHO.
Oh Callum you didn't pick it up this morning but I was hearing you on 15m backscatter when your were out portable last weekend.
Surprised you heard me on 80 with my 3.5w this morning. Oh it was on an inverted V fed at 12ft agl. De MI5JYK.
Peter, your 3.5W was pretty good!! And OK on the back-scatter. Not a lot of people are aware of that.
Always learn something interesting. Thanks Callum.
Hey thanks!
Calum I've been using I verted V for 40 years what I was trying to convey is that your elements are in a straight line ie North South what I was wondering if you could model the legs being at an angle of 90degs to each other ie South, East or East South not in a straight line!
I see.. It doesn't matter. It would hardly skew the pattern at all..
Always good stuff Callum here’s from across the pond W9US
Thanks for the honest physics of RF going into Antennas. I enjoy watching your camera work for its candid frankness and not the shameful shilling for a product to make a sponsor happy and grow your wallet. A perfect example is the ongoing promotion of M&P Coaxial cable. It could be the most perfect coax in the world but the hardsell delivery from some UA-camrs is so patndtic6 it's off putting and causes so much doubt about their integrity to create much doubt over any review they've done before or after their M&P "infomercial" style presentation.
Your videos mostly encourage experimenting and using impartial physics with personal results to achieve a common goal of having fun, getting signals way of into the wild blue yonder and best of all not spending an inheritance on a hobby.
You always seem to be the teacher first before the antenna maker CEO and that alone is a great marketing technique as well as making this hobby better for all! Thank you kindly for being you. 73 Craig
Craig. Yes, I think inspiration comes first! Thanks.
I’ve been installing a 40m Inverted Vee in a row of trees in my backyard. I cut the wires a bit longer than the antenna modeling apps suggest and started tuning. The wire I used is solid copper, 12 ga., with insulation. My best resonance (~1.5 SWR at 7.034) was achieved with each wire at 29’6”, much shorter than the estimated 33”.
I’ve been able to find information on the web about velocity factors of copper wire (about .95) and insulation (about .95 to .98) and Inverted V versus flat configuration (no value was provided).
If I consider those velocity factors and do a little math, I get this for a length (divided by 2 at the end to get a single leg length):
(486 x .95 x .95) / 7.075 / 2 = 31.17’
Consider some additional shortening due to the Inverted V configuration and these numbers start looking rather accurate and interesting.
I’d love to see a video on this phenomenon!
Great stuff; thanks for all your work and content. Very helpful to us new hams.
I have touched on this.. But it will be velocity factor and "end effect". I will try and find the video..
OK, best I can find is this one.. ua-cam.com/video/0UwaIc3GdSA/v-deo.html But it's the "End Effect" that is making it shorter. And height above ground.. That also affects length.
@@DXCommanderHQ Very interesting. And thanks. Too, and as you suggest, height above ground matters. I’ve played with that using EZNEC and you can see the SWR dip move as you raise or lower the antenna height while keeping all other things constant.
Damn fascinating stuff, antennas!
Hi Callum your model is with the 2 legs Inline I was wondering what the result my be if the legs came down at an angle of 90degs to each other instead of being Inline
90 degrees to each other... That's an inverted V..?
Thanks Callum. I have wondered about this. Would the effects remain the same with an EFHW? Flat top vs Inverted V. And of course even with the dipoles, I have seen them mounted as slopers.
Don, I think IN THE MAIN unless we go about half a wavelength above ground, we will be "bubbling"..!
Very interesting Cal, I would never of guessed the height made such a difference to the directional properties of the antenna. Question: Does refection from coax / feeder affect the performance of the inverted V antenna and if so can it be calculated?
1/2 wave dipoles at 1/4 wave height don't work very well, you really need to be closer to its halfwave length above ground. Critical for 80 and 160m
John, I wouldn't worry about the coax (for our simple experiments)..
Well said!!! Thank you!
Thanks for watching!
Calum have you modelled an inverted V with the legs at 45deg but coming down at an angle of 90degs as if the center was at the corner of a garden one leg running down the side the other along the back.
Eddie, you will have to explain that again slightly more detail because in my head that's what I have, I'm so sorry. PS - I probably won't see your comment (the system doesn't let me follow threads). So maybe make a new comment and I'll see that.
Callum, I've just started getting back into ham radio after a number of years. I used to use a 108ft trapped centre fed dipole which was ok because I had the room.
I now have smaller garden and am using an ex military centre fed dipole , each arm is around 40 meters long. I have raised the centre feed point to a height of around 21ft, but I've had to keep both arms of the dipole parallel, but spaced throughout its length using 6" spacers. The end of the arms are around 9 ft off the ground, so it looks like a sloping end fed but with two wires. How will it perform?
So many variables.. Depends on which frequency but at 20 feet, in the main it will be mostly omni-directional I think.
I love inverted V's....easy to work with
Yes they are!
@@DXCommanderHQ another good thing is even if you use top quality stuff you can still build a 40m EFHW for $125 USD using real antenna wire, insulators, UnUn and cable ties..
I'm just getting back into HF after about 10 years. I used traditional inverted v antennas on 80m and 40m. I'm wondering what happens to the directionality of the signal (horizontally) IF each end of the wires are the same height (say 30 feet) as the feed point height of 30 feet and the angle of the antenna / distances of the wires is changed. Does that give gain in a certain direction or signal cancellationin all directions as opposed to a trafitional inverted v? Thanks
At that height, you will only have a 3dB difference between off the edges and off the sides.
@@DXCommanderHQ Thank you for that information.
Flat top dipoles are very tricky to find the sweet spot but if you persevere you find an orientation and tune that suddenly opens up a band. My patience is normally too short for this but once once in a while I go for it and the signals flood in over the top of what is incessant background noise at my QTH. I have no idea why but it does. M7BLC.
I run a 40m 1/2 wave and an 80 1/2 wave, both almost flatop both 50ft high. Stick to the 468/F rule and you'll get resonance every time for the freq you cut it at.
What about the flat vs the inverted V in polarisation. As a flat dipole is horizontally polarised you will loose some DB making contacts with guy's running verticals.
Would the inverted V give you more gain with a vertical contact?
Not really.. The polarisation changes as soon as you hit the ionosphere and is then completely unpredictable.
@@DXCommanderHQso ideally we need a horizontal and a vertical on same band with a switch
Something you might find interesting is to reduce the angle between the legs of the inverted V,, the feed impedance does drop but the pattern is useful and the aerial will fit in a smaller space. 73
Good idea
HI Cal, Does the Inverted V have less noise than a vertical?
Depends on the environment. Some folks have noticed LESS. Remember, it's not the antenna that's noisy - but the crud that's making the noise :)
My horizon 40m dipole east west gives me about 3 db in a south direction, over my slightly higher 46feet high inverted v 204feet doublet .
So more or less in line with this conclusion.
Is it worth the 3db ? Normally I would say no , but living in NE Scotland and working mostly 300-1000km skip distance England and near Europe, that 3db just gives me that slight edge, so it stays up meantime.
AH OK.. Swings and Roundabouts :)
I have read somewhere that 22" was optimum angle for an inverted V.....true?
Sounds like utter myth and baloney from folks who read too many books and no experience :)
@@DXCommanderHQ thanks!
"Antenna Guru" you may well be... but I always think of you as the "Wigglies Wrangler". 😀👍
Wiggles Wrangler!! LOL
I see a lot on dipoles. Is there any interest in doing Off Center Fed Dipoles? Or am I "beating a dead horse"?
I have one that covers 10 to 80, and works well enough actually. Just make sure you get one, or build one with a proper 4:1 balun and a separate good quality choke.
OCF dipoles are an interesting subject. Not made a video about that but once you get it, possibly easier to multi-band (well.. SOME bands!)
What about a non-inverted "V" 4m up? Thx AC4OW
You mean a V.. Haha.. Problem then is that the high current is very low down.
I don't know wat that means. I was curious about directionality and take off angle. Thanks, AC4OW
I think you are well off on the patterns it's the side views that are important they are your take off angles not the top veiws. I've been using nec2 for a couple of decades to model antennas. Yes there are omni directional patterns with inverted but not quite how you are describing it a 3d pattern will make you see this more clearly.
That is the reason I love my inverted v , easy, simple and works always. also on a 5 mtr high pole. The angle that is the one thing that must be precise , 90 degrees or more
sir can you please show how to create a inverted v dipole in ansys hfss software which is in student version in google and it is free of cost
Here is a dipole using that software. .. You just need to change dimensions.. ua-cam.com/video/ifhj6kDVbWs/v-deo.html
I run a 20 meter speaker wire double inverted v on a 7 meter squid pole for SOTA. 1/2 wavelength feed line zip cord then split it for another 1/4 wl and tie an electricians knot at the split to stabilize the junction. Connect to radio with binding post. Would love to see it modeled vs conventional dipole. KG6HQD did a bunch of empirical work on it before he git sick and i followed his design tips. KC6ARY
It would be interesting for you to lose the "double" one day because I'll bet you probably won't notice UNLESS you have terrific height.
@@DXCommanderHQ sorry for the typo - "doublet"
Hi! Can I place a double bazooka antena for 11m at a different angle than 90^? Thanks!
Yes you can.. Patterns are weird things you will you will be stonger over "there" and less so over "there" (wherever "there" is : )
What software do you use for that?
It's called MMANA.. I have made some videos specifically about that.
Is this antenna better than a endfed
Well, TBH I'm not an end-fed man. It's a sort of "free lunch" and does everything and nothing (for me!). I think if you have the time and engineering, dipole would be "better".
sir can you please show how to create a inverted v dipole in ansys hfss software
Well, if you can get me a free license, I will try - but it's very expensive software.
it is student version where you can download free in google sir@@DXCommanderHQ
G’day Callum,
I have 2 questions.
1. Does the composition of a tower/pole effect the performance of a vertical antenna (or any antenna I suppose)? i.e. metal pole V fibreglass pole?
2. Is the effective output of a multi-band antenna less (ie is the power spread across all the antennas) than a mono-band antenna tuned to a single frequency (ie all power enters that single antenna)?
Really appreciate your videos!
Terry VK2SOT
1. Erm.. not really. Ignore it. As you would a boom of a yagi. 2. The RF has to "get out" somewhere. YOu can't really make an more or destroy the energy so if designed well, it shouldn't matter UNLESS it's full of traps. Say DX Commander Vertical has exactly same efficiency on all the bands when compared to mono.
Screw it. Just get a DX Commander and be done with the whole mess.
HAHAHA!
Why don't you write a book(s)
Time. I enjoy videos. I am half-way through a completely different book to ham radio.. One day..!
Do you measure the 90deg wire angle at the center insulator?
Not really.. About is good enough