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- Опубликовано: 17 сен 2022
- In this episode Shahriar discusses the engineering challenges associated with making good RF & mm-Wave cables. The significance of the connector, cable frequency range, loss, phase/amplitude stability & temperate are all examined from a theoretical & practical aspects.
The stability of Junkosha cables are demonstrated up to 50GHz through S11 & phase measurements. The Junkosha MWX7 series cables offer optimized PTFE dielectrics as well as some of the best phase/amplitude/temperature stable operation:
www.junkosha.com/en/products/...
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A characterization of common aliexpress SMA cables would be very nice. Many hobbyists uses them for RF assemblies.
what about F and BNC and other types for under 20GHz?. I would be interested in seeing that as well..
Meanwhile in ham radio world:
Nice review - I didn't know how good those Junkosha cables were - impressive.
Now I know high frequency measurements are impossible because they don’t like bending, moving and heating. While the technology evolves over time, we are still encountering the same problem
At 50GHz, every cable is a 3dB pad XD
Dear viewer, If you need to ask the price, this Frequency is greater than your bandwidth.
Nice video. I trick I do to test return loss stability is Data->mem then display Data-Mem, the cable will be flat across the band at the system noise floor. Then bend the cable and you see the true residual. You can also see the relaxation this way by bending and hitting data->mem again and watch S11-Mem move as the PTFE inside settles into it's new shape. In your video, you see the rise in S11 on the trace initially (which should be at the noise floor directly after cal) likely due to a slight cable movement/relaxation when you did the OSL cal, maybe due to moving slightly the cable after applying the load. Or just a bit of temperature drift. You can test the phase stability of a cable by putting a short on the cable, Data->Mem and Data/Mem and then you can see the two-way phase change. But, to quote myself: cables are like dogs, either they are bad, they've been bad or they are going to be bad, and if they are good, they only stay good with great care.
Here's me messing around with coax splitters and phasing harnesses at 500MHz and below, and you come out with a video showing off 100GHz. 🤣🤣
I've noticed this effect before, the shifting of S11 values as the cable moves. Thus far I've been working under the assumption of that the shielding is not perfect, and as the cable moves the shielding provided differed and thus affecting the amount leaking out of the cable, which, in terms of EMI, bothered me to no end. Nice to know that it could be due to phase difference... I wish I had cables can take such levels of abuse...
Shahriar, I always love the stuff that you produce but this episode in particular was worth it’s weight in gold for me. Thank you so much for doing it!
Excelent content. Very instructive.
This was a great walk-through! I went ahead and bought some Junkosha cables for my VNA setup after watching.
I can personally attest to Junkosha's quality as well. Fantastic product and superb customer service.
You have a truly great gift for explaining complex things with incredible clarity. Thanks for making this video--I'll probably never use a cable like this in my little hobby lab but it's cool to learn about it here.
Eye opening!!! Thank you, Shahriar!!
Excellent video, thank you! This kind of information is not common to stumble across, so thank you for the opportunity to learn some new things. Cables, connectors, switches, all that stuff has obscure but important characteristics.
Great video! Would definitely be worth sharing to coworkers .
I didn't think I would be interested in this topic, I got hooked. The cable testing was fascinating. Thanks!
Really nice demonstrations, that Junkosha cable is excellent. What you are measuring are the so called stability and recovery of the cable, both for magnitude and phase. For evaluating these parameters, I prefer connecting a short at the end of the cable under test.