Yagi Prototyping What have we learned?

I wanted to do a separate video explaining what I hare learned over the last 18 months. Hopefully I have answered any questions you may have. If not then please feel free to ask. Although it is fair to say I still have questions myself.
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[@andrewmcneil]

Please feel free to ask any questions that I have not answered. Although it is fair to say I still have questions myself but that is why I love this subject!

[@irschn1671]

wi-fi is not a problem - use repeaters and that's it! But to receive LTE signals, THAT'S THE PROBLEM. For example, the antennas on b1 b3

[@milesprower6641]

it looks like its just capacitive loading on the antenna, though the metal of the tube. the tube is conductive and thus increases the surface area for charge to accumulate, this increases the effective capacitance of the antenna elements, lowering the resonant frequency. (this is my theory at 4min 30sec)

[@HG-nv8fk]

Hey Andrew love your videos and have made a number of your ants. Also modified frequency for my needs. Great work. In relation to the shift in frequency with to additional length, if I remember my lessons on wave guid theory, some decades ago now. It may have something to do with the inner diameter and the mode of propagation with in a wave guide. I could be wrong but worth a thought for you and any one more learners than I. But I am very interested in you experiments. It keeping my brain very active. Great content and look forward to more. Richard.

[@k.o.0]

Excellent experiment! Andrew could you go back and compare your bifiliar antenna from 8 years ago against your biquad antenna from 5y ago? You never had a spectrum analyzer and I would like to see these 2 omnidirectional antennas pitted against each other !! Thank you!

[@andrewmcneil]

👍👍

[@k.o.0]

Andrew one more question since you are prototyping - can you compare copper reflector to aluminum reflector (from a coke or beer can)?? I would love to see if it makes little if any difference. Obviously the latter is free compared to copper plate! Thank you!!

[@highflowhighflow9896]

this remembers me years ago when i was setup a 5 element yagi for the HF spectrum on a flat roof; the distance above the roof did make a lot , indeed swifting the center freq for best SWR, i needed hours to get it right. My idea for the Cantenna is not cut down a working wifi antenna but change the diameter size of the tube....

[@aaltvandenham]

Very nice experiment. Neil, what you call capacitance, can also be internal wave resonance. It is over 50 years I got a few lessons on Technical University Eindhoven. But until 10 years ago it did not interest me so much. Go on please 🙂👏

[@andrewmcneil]

You could be correct I am saying capacitance because I know that will affect it in this way. But who would think a simple metal tube could be such a mystery!

[@gabrielsansar6187]

`scratching my head` count - 173

[@andrewmcneil]

Way more than that😁

[@pasixty6510]

These are very interesting insights. Thank You for making all your innovative experiments and videos. 1. I am not so much into microwave stuff, but I think in general most of my HAM experience in UHF applies here too. So I totally aggree, most of the frequency shift in the pipe must be caused by adding capacitance to the arrangement. We know that a so called capacity hat lengthens a wire antenna electrically, making its resonant frequency shift down. Should be the same here, I guess. 2. I think you needn‘t care too much when there are low return loss ‚spikes‘, as you call them, as long as your transmitted signal is ‚clean‘ enough to not hit these spots.

[@andrewmcneil]

Thanks for sharing your insights and knowledge

[@ve7hun]

Andrew, I love your videos. Have you considered a circular patch as the DE for the waveguide? That might decrease the capacitive coupling by not having corners so near the waveguide walls. I also have a feeling it might decrease the Q a bit and broaden the bandwidth.

[@andrewmcneil]

Tried it years ago but was not impressed maybe I should look again now I have the tools to debug it.

[@lainmonro9641]

Really enjoyed this many thanks

[@andrewmcneil]

Glad you enjoyed it

[@Dan-ze8lb]

Hi Andrew, thank you very much for all your superb videos! I watched a lot of them, but i am still unsure which antenna type is best to use as a wifi "sniper". Is it the Patch fed Yagi (cantenna?), Biquad Yagi (cantenna?) or else? The mk2 is too huge for me :D Thank you!

[@andrewmcneil]

The one I am building at the moment might interest you

[@Dan-ze8lb]

@@andrewmcneil Can i get more information at your patreon? :)

[@Seriouslydave]

I always have questions that i didnt before. Most of them are probably fundamental mistakes new people make. But i really want to know what you think about AI in somehow aiding design? Do you think it would hinder results or speed them up, maybe ai will see things we might not? I first encountered developmental design watching the americas cup as a kid. And the behind the scenes of team new zealand. It just interests me watching things improve.

[@tmpserg]

it is close to SWR DISCLOSURE type of video which some of your subscribers requested before (:

[@CornholioNan]

Not exactly...in swr disclosure Andrew could show few of his old known finished disigns with swr-measurment, not this kind of variations debuging

[@andrewmcneil]

This is more to do with capacitance and the change in frequency. Most of the time reflected return loss due to transmission line mismatch is easier to solve because you can always add some sort of balun or taper to match 50 ohm’s. But as for VSWR it will be the new year as I want to talk about measurement in general.

[@lainmonro9641]

@@CornholioNan Maybe he could remake some older videos but as new builds from what he has learned. As for return loss and SWR there are conversion tables on hp website it is not hard.

[@tmpserg]

@@andrewmcneil ,great! But will you make BIG video with swr of your old famous antennas from your old videos?

[@andrewmcneil]

I will revisit some in the new year, yes.

[@34snip]

Great video with nice explanations. The only question I have got is, why have you chosen the 2.4 wifi frequency ? Where on a typical wifi range for internet access (house + garden + shed...) It is rather simple to use cables and add AP. Is it more relevant to work on mobile internet access for mobilehomes or isolated homes ? I don't know 😁 you have probably good reasons 😁

[@Kangsteri]

Cool. Have you tried just forward angle parasitic reflection plates / rods on the sides to make it more directional? Or under and above it. Closed sylinder will have static charge around it. Anything over half a ball / tube will have positive charge on the surface and negative charge inside.

[@andrewmcneil]

Interesting I have seen this used on waveguide transmission lines but never thought of using it here.

[@GregAtlas]

Layman here: I get that the increased capacitance throwing off the frequency and that's bad, but are there any advantages to having a larger driven element?

[@paul_daniels]

Have you done any kind of software modelling of the cantenna style yagis? I'm interested to see if they have superior gain or f/b patterns compared to a standard yagi

[@andrewmcneil]

No but I have recently been gifted a licence code to some very expensive software from a subscriber that is capable of modelling various Yagi’s including this one. I will be playing with it over the holidays.

[@paul_daniels]

I can model standard yagis but I'm not sure how to model them inside of a can. For someone like me who hikes with HF radio gear a cantenna would be a far more durable antenna than a standard yagi on the 23cm band. I might have to start tinkering here, I'll be keeping a close watch to see where you go with this @@andrewmcneil

[@sarandeepsingh921]

Hi andrew i was working on making 698-6000mhz log periodic dipole antenna with 11+1dbi gain my calculation in the end is not accurate for as per the testing results last dip stuck around 3800mhz, Can you get around making this antenna ? and maybe your previous aluminum tube lpda antenna can be modified with some calculation to target max 6000 mhz a great 4g5g lpda antenna video can be done on this too !!

[@leozendo3500]

line the inside of tube with ceramic or some dielectric to decrease capacitance?

[@andrewmcneil]

Would make a nice experiment in regards to dielectric constants 👍

[@gigigigiotto1673]

Hey, could you or someone from the community point me towards your latest video about diy cantennas? I saw the one from 8 years ago, but not owning test equipment of my own i'm afraid to damage the wireless adapter if the antenna has an high SWR.< Thanks