Introduction to Waveguides using the LiteVNA, Part1, Homemade Waveguides
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- Опубліковано 8 січ 2023
- This video shows my attempts to construct some homemade waveguides and experimenting with them using the LiteVNA.
EEVBLOG thread, Experimenting with waveguides using the LiteVNA
www.eevblog.com/forum/rf-micr...
I’ve been teaching microwave polarisation wrong! - A Level Physics
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You mentioned you are not a ham, then proceeded to do more radio experimentation than most hams I know ever do. I encourage you to join us in the hobby. You'd be an amazing resource for a local club and might enjoy working uWave with others. 10 and 24gHz are popular for hams.
I have mentioned that I had a license when I was younger and had a lot of fun with it. To this day I consider it a stepping stone in my education.
Hi Bob, the biggest barrier to that cadre of hams is not the technical proficiency but the economic ones. I was a Navy Fire control tech. I learned many field expeditious techniques to operate, including the art of simple dimple tuning wave guide. With a $60k VNA. Should the cost of gear ever come down to earth the popularity might increase.
Many years ago, I would tune dented waveguides by putting opposing dents at specific distance from the original dent. This was done in a combat/battle situation to keep the gear operational. Had to do many hacks to keep the equipment running. Active/passive equipment operating from 3mhz to 18ghz!
I read something similar about tuning them. This was posted on Microwaves101: "Once you find a spot that improves performance, mark it with an "X", then you can either drill and tap it and insert a tuning screw, or it's "hammer time" and you can use the concept of "dent tuning." This was contributed by Bob Luly, thanks!"
From someone who knows nothing about wave guides, I found this video fascinating. Well done! 😊
You and me both. It's a learning process and I'm just starting out. So much to learn....
Thanks very much Joe! Cool DIY lesson about extending the frequency range of the NanoVNA, which I love.
Glad you enjoyed it. I demonstrated an extender back in 2019 to push the NanaVNA above 1GHz. I believe I posted about it on EEVBLOG. The first time I tried was with my 1970's HP8754 where I pushed it beyond 6GHz. Back then I was far too ignorant to pull it off. Or, let's say too ignorant to know I was chasing my tail.
Amazing video Joe, thank you for your contribution.
I am an ECE student. The last few months I have been studying antennas in my spare time. Currently going through Dr. Balanis' book.
Your videos are one of the things that drew me into the field.
I wish you the best from Greece!
Good luck with your schooling and career path.
Thank you for this video Joe. It's as clear and detailed as usual for your presentations. They are all excellent work. I'm interested in your LiteVNA mods. I'll double check your previous videos to see if you did a video on them. I'll also go check for anything further on the EEVblog. If there is nothing already published, your mods might make an interesting and useful video. Again, thanks for your work.
For the LiteVNA, I was looking for some low hanging fruit but never found any. Gains I have made were very small. After all of the changes I have made, I'm actually surprised it still works.
Thanks a lot, for sharing this very interesting experiments. This is why I loveYT and prefer the "smaller" channels of real experts to the journalistic "million" channels.
Dr Southworth would be an expert, I'm more the tissue he would have used to blow his nose on. It takes time for me to learn and you get to watch it first hand.
@@joesmith-je3tq Of course, I also respect Dr. Southworth and many, many other pioneers in science and technology. I als respect and like your modesty. But there is no reason for you, to hide your light under a bushel. Kudos and thanks for your great contributions!
@@klassichd10 WWW, World Wide Web. Making videos for the entire world to watch hardly seems like hiding my light under a bushel. I have started to work on Part 2, so stay tuned.
Most. Excellent. Video. Sir!
I was highly skeptical that any VNA under $200 could be worth a damn... you have put me at ease.
Well, its going to depend on what consider to be worth a damn. All of the low cost ones I have looked at are very good learning tools for those just getting started. If you want to make narrow band measurements and experiment below 300MHz, the $50 unit I have is a good choice. Above 300MHz, I like the LiteVNA. Combined will set you back about $200 USD.
This is an excellent video. I learned quite a bit watching this! Thank you.
You have also convinced me to buy a lite vna 64. I have many filters, splitters, amplifiers, and isolators that are above the 1.5 GHz limit of my Siglent SVA1015x that I would like to characterize.
Do you have a sheet metal bender or did you bend the sheets in a vice?
I tried using a bender but the vice with a ball peen hammer provided much sharper edges. I have been looking better parts for these experiments but haven't had a lot of luck.
Amazing work! Was really fascinated by the handmade waveguides, filters and horns, you made it seem all so simple so I'm keen to try making some myself. I have access to a resin 3D printer, so if I did this I would try printing cavities using that and then spray coating a conductive layer. I know the signal path had a go but he used a filament printer thus had some issues with dimensional accuracy. Anyway, thanks for the inspiring video!
I'm happy to hear that the video made things clear enough to get you interested in experimenting. I have seen some waveguide parts that were 3D printed. At these lower frequencies, I would think it's possible. Problem may be in how to handle more shapes. Maybe they could be split like what I am doing, spray coated, then bolted together.
@@joesmith-je3tq Wouldn't the 3D-printed surface be somewhat rough for such short wavelengths and absorb some of the wave energy?
I have been experimenting with 3d printed waveguides and coating the interior with gallium because of it’s low melting point and high conductivity.
Really cool demos. I wonder what the influence is of closing the seams on the box, or aligning the panels closely vs loosely. Possibly a lower Q with some leakage around the box, but I can't imagine having a huge effect at these frequencies.
You could kind of see how poor the response was until it was closed up.
Thanks for the hint, I could kind of see that, but the box was hanging in mid-air. Was just wondering if there is a big difference between just tacking the sides vs smoothly joining them.
@@ligius3 If you own a of these low cost VNAs, I recommend you try it for yourself. As I have shown, you don't need to spend a lot of cash to play. That's really the best way for you to get a feel of how things behave.
I mentioned in another comment about starting with rubber bands to hold them together just to see if things were even remotely doing anything. The first filter I constructed was the long brass one. I had left it unsoldered and used some copper foil to hold it together. The performance was very poor. After playing for a while, I soldered it up and it started working. Still, I would imagine, better materials, better bends, better clamps, you may get good enough performance to meet your needs. Very subjective. The seams I show are also poorly located. I made this choice to ease construction. Outside of my home experimenting, we wouldn't make a waveguide like this.
This was fascinating, and I think I'm hooked on wanting to know more about your extender and the topic as a whole. I do have a question, that might seem basic, but for which I've never seemed to have come across a proper answer - What impact does the thickness of the material used for your waveguides and filters have? Is it purely structural, or does it influence the conductivity of the guide?
Edit - Your next instalment has literally just dropped - 58 mins ago, so basically the watch time for this and composing this comment ago. I hope to find an answer there.
As the frequency increases, skin depth decreases. At the frequencies I am working at, the thickness of the material will be availability, how difficult it is to work with and how stable it is. The plan is to start testing some 3D printed parts. The thickness of the conductive layer is much thinner.....
@@joesmith-je3tq Excellent, thank you for your reply, I've also wondered if using expanded polystyrene used as a buck/former (I understand it has a permittivity very close to that of air) and then applying thin copper or aluminium foil to make up a resonant cavity would work. The idea came to me while exploring whether to make a slotted waveguide for an extended WiFi link. It just seemed like it might be an inexpensive way of experimenting.
@@squelchstuff I believe that will greatly depend on how you define "work" and your skill level. No reason you couldn't try it. That's all I'm doing. Just playing around experimenting.
Plumber's copper tubing might give a fine wave guide
Witchcraft!
I wonder if al/cu copper tape would seal your guides ok?
Happy new year Joe.
The very first test I ran, off camera, I used rubber bands to clamp it together. Not the best performance I've seen but worked well enough to give me some idea that things were moving in the right direction.
Thanks for sharing the amazing video! What is the tiny metal tube in the Extender Board? Is it a coaxial cable or waveguide tubing?
How about a timestamp? I thought I went over every component but maybe I missed something.
@@joesmith-je3tqyou are so kind, thank you so much! and sorry for the unclear question. The timestamp is 52:09, I am curious about what is the shinning metal tube in the middel of board route like 'S' shape, and the one on the left upper corner route like rounded curve and the one below the 'S' tube and route bended up to the bottom. Are they all the same kind of components? And what they are? Thanks 😀
It would be appreciated if you could make your videos available in 1080p. The screen captures are fairly blurry at 720p
Doubt it will happen any time soon as I have better things to spend my money on. Plenty of channels out there though if you need higher res.
I come to your channel for the excellent content. I don’t know it others that cover the same topics you do.
I’m not a UA-camr video person and don’t have a lot of expertise here, but I wasn’t anticipating that uploading higher res videos would cost any money. Your camera/video resolution is fine, it’s the screen captures… much of the text in your solver32 application is unreadable. I assume your monitor is 1080p or higher. If your camera is not it would be fine upscaled to 1080, uploaded at 1080.
I’ll watch your channel regardless, it was just a suggestion.
@@jonboro2000 Not being a professional UA-camr myself, I don't see it being worth the effort. I'm sure if I were attempting to grow the channel and draw any sort of income from it, I would look at things differently. Odd about you not being able to read much of the text from the screen capture. I don't have any problem. Is your connection throttling the resolution? You can force it in the YT settings.
I have a question about my fluke 789 and figure there's a lot of really smart electronics ninjas on here. Without any leads in the meter it reads about 5 mega ohms. Any body have any good ideas what would cause that. I'll probly send it to fluke but I'm curious 🤔
Respected Sir, Could you please explain the meaning of different standing wave modes e.g., π mode and 2π mode etc.
Let's assume you completely watched this video. Did you have a detailed question about when I went over it?
This was a really good presentation ! I'm surprised your not a "Ham" , our hobby would benefit greatly if you were. I got a chuckle out of that old article, There is a whole group of hams that play with 10ghz and greater these days. 👍
Not being a ham or CBer has never limited me when it comes to my hobby.
I would have to agree 100% by your knowledge and presentations.
Hi Joe! Great video. I'd like to reproduce your experiments, but I'm new to this, so I need to ask a new guy question. How did you make your wave guide antenna probes? I see you used an sma connector, but I'm not sure about the wire to make the antenna. Did you solder it to the center post of the male end of the connector or insert a wire into the female end with solder (if so, what gauge)? Why is it covered in dielectric?
Also I've seen diagrams in some books where they will bend that wire and touch the side of the rf cavity or wave guide. Any thoughts on the performance differences in that case. I'm assuming that creates a loop antenna. Does that create a TM10 mode?
Thanks,
Tom
I'm not sure what an antenna probe would be it sounds like you are asking about the coax to rectangular waveguide transitions. If so, I soldered wire or in some cases, brass tubing to the SMAs center post. In some cases, I just stripped the coax using the exposed center conductor. I suspect your question about dielectric was from that first large homemade waveguide with the red protective caps. These were there so I didn't snag the wire when working with it for the demo. They were removed when I was ready to solder things up.
At 9:37 I mentioned the shorted elbow. There are other types as well. www.rfwireless-world.com/Terminology/coaxial-line-to-waveguide-transition.html
@@joesmith-je3tq Yep, that's what I was referring to, in all cases. Thanks!
cavity filter .
resistor
You're too smart for me Joe, but I enjoy your content.
I know a little bit about a few subjects is all. Guessing there are areas you know, where I am clueless.
a couple of major flaws in this design. you should never cut the WG at the corner lines. That's where the transversal current on the walls is maximum so any small gap even hardly visible by eye will radiate quite easily. Instead the WG is always made from two halves that are cut in the center line and screwed together. That's where the transverse current on the walls is zero. The longitudinal current on the walls is maximum at the center line but since it is parallel to the gap (cut) it will not radiate.
The second isssue is that the distance of the coaxial pin must be quarter of "GUIDE WAVELENGTH" from the end wall. That is quite different than the free space wavelength that you used here so the input VSWR will be hard to adjust. The guide wavelength (wavelength of the guided wave in the tube) is LARGER than the free space wavelength at the same frequency. I cannot type the formula here
I take it you didn't actually watch the video and just felt the need to comment.