Mastering Stability and Reliability of RF/MW Cable Technologies

Guests Dan Birch and Ron Souders | Uploaded : 28/05/2024

The EEcosystem Podcast

Mastering Stability and Reliability of RF/MW Cable Technologies

In this week’s episode, RF/Microwave Cable technology veterans, Dan Birch and Ron Souders discuss the challenges of maintaining the stability and reliability of these crucial interconnects. They unpack which applications drive tighter performance specs, increasing channel complexities, and why stability is a critical concern for design & development engineers.

Episode Links

Nitrowave Cable

Samtec IMS 2024 Page


Sponsor Resources
  • πŸ“˜ Visit The EEcosystem Website For a Free Download to: Samtec’s white paper: Wideband
    launches: Much more than Footprints on PCBs. and receive a free 90-day subscription to all of
    Eric Bogatin’s training at The Signal Integrity Academy

    πŸ‘¨πŸ½β€πŸ’» For free Technical Resources and to Learn more about Keysight Pathwave EDA Software
    Solutions visit the homepage now.

    πŸ”— For all of your high-speed and RF connectors visit the Samtec website and access excellent
    engineering resources while you are there.

    ⛰️ Visit Summit Interconnect for all your complex PCB manufacturing needs.

    πŸ”— Visit Isola Group global for High performance laminates and prepreg materials for PCB
    manufacturing, as well as new IC packaging interposer

    πŸ’½ For high complexity EDA solutions visit SIEMENS EDA Website

    πŸ’‘ For a free subscription Signal Integrity Journal and articles about SI/PI/EMI, news and
    technical resources follow the link above.

    πŸ“¨ Subscribe to Analog io a grass-roots weekly Newsletter written by hardware engineers, for
    hardware engineers!

    πŸ“‘ For Custom RF and MW PCBs visit the Transline Technology Website to learn more. Visit

    πŸ”Œ Picotest specializes in high fidelity testing and measurement tools, primarily for power-relate
    applications. Visit their website for more product information and excellent training materials from
    expert Steve Sandler


								 Judy Warner (00:00.89)
Hi Dan, hi Ron, thanks so much for joining us today. We're delighted to have you on the podcast. I know that you're both pretty new to Samtech, so why don't you first give us a little backstory of how you ended up at Samtech and more specifically your focus is on RF and microwave. So tell us the story behind you joining Samtech.

Dan Birch (00:21.861)
Okay, let me start with that one because Ron and I actually have what I think is a pretty interesting background. He and I both started our careers at the same small company, this place called Microcoax, back in the mid 1980s. So he had just been hired as a new engineering graduate and I was hired as an engineering co -op at right about the same time. And ever since then to this day, Ron and I have been...

working on microwave interconnects. Uh, so, you know, you can imagine our age here. I was joking to myself that, you know, this is, I think our first podcast together and hopefully it's not our last. But anyway, yeah, I'm sorry. Fast forwarding. Um, I joined Sam tech about five years ago and you know, I was brought here to grow the size of their RF interconnect business.

Judy Warner (01:03.13)
Well, like yeah, go ahead.

Dan Birch (01:18.789)
You know, and for RF interconnects, you know, you basically got connectors, adapters and cable assemblies and Samtech does pretty well with all those. But if you really want to get a lot of growth, cable assemblies is extremely important. There's a lot of value added to the customer there. So, you know, I was charged with growing, growing the business. I wanted to grow it with cable assemblies, but you know, we needed something special. What we needed was world -class cable.

And when we were thinking about that, I'm thinking, I know who we should call. And that's when Ron comes in.

Ron Souders (01:54.344)
Yeah, I didn't actually know that much about Samtech when Dan called, and he went there and a couple other colleagues and they had a good reputation in the industry. Dan invited me to dinner with the CTO, Brian Vecic, and if you ever met Brian, he's a really, really, really good salesman and passionate about Samtech. And he talked to me about the philosophy, how they grow the business organically, and his vision for Nitrowave, and as they say, the rest was history. I...

I was on board hook, line, and sinker.

Judy Warner (02:28.322)
Drink in the Kool -Aid, gentlemen. That's a fun story. So I guess what I'm curious about, what I think our audience would be curious about is what's driving specifically that interest and growth at Semtech. Like I'm sure there's a market driver that pushed you both and the company in this direction. What is it that you're noticing?

Ron Souders (02:29.544)
Drinking, yeah, absolutely.

Dan Birch (02:30.157)
I'm to go.

Dan Birch (02:55.941)
You want me to go on that first one? Yes. So, um, you know, Sam tech, a lot of Sam tech business and a lot of Sam tech success in the past has been with high speed digital, uh, interconnects, you know, we're, we're a clear world leader in that and you know, high speed digital, you're talking about passing signals around and differential pairs on a printed circuit board, um, or in twin ax cable.

Judy Warner (02:57.242)
Go for it. Sure.

Ron Souders (02:57.64)

Dan Birch (03:24.165)
And with the Twin Axe in particular is where, you know, Samtech's already enjoyed a lot of success. They figured out decades ago that the performance of the actual raw Twin Axe cable could be a key differentiator, uh, and helping customers with their performance needs. So, you know, they set up a whole cable plan. That one's in Oregon that just focused on designing and fabricating, uh, the best.

high performance Twin X in the world. And that business model was a success. So, you know, part of this was like, look, can we just recreate what was done here in the coaxial world? And once again, that comes down to that world class cable. If we can have the world class cable, then, you know, that's going to make a difference to the customers and they're going to buy our cable assemblies. That's, you know, it's really not rocket science.

Judy Warner (04:02.938)

Judy Warner (04:20.602)
You have any more thoughts on that Ron?

Ron Souders (04:24.232)
Well, you know.

I'm drawing a blank.

Judy Warner (04:28.6)
If you don't, that's fine. We'll just take that out. Okay. So, Dan, you just mentioned Nitrowave, which I believe is a brand name. So why don't I'll let you gentlemen choose who wants to tackle what that is and again, what the market drivers are.

Ron Souders (04:46.728)
Sure, sure. Nitrowave, it's really the newest microwave cable in the market right now. It's exclusively available from Samtech operating up to 110 gigahertz. It's unique. It doesn't follow the traditional rules that have been around probably for the past 50 years. I think it's truly going to raise the bar for the entire industry because the driving force behind Nitrowave was really to create the most electrically stable and reliable microwave cable assembly in the marketplace today.

Judy Warner (05:17.882)
So talk about that stability piece a little bit. That's not really in my wheelhouse. And what is the differentiator as far as stability or instability when it comes to a product like Nitroid?

Ron Souders (05:21.128)

Ron Souders (05:31.528)
Right, right. Well, yeah, I probably should start explaining what we mean by stability, right? Well, in general, there's four electrical properties that define the performance of a microwave cable. You know, insertion loss, VSWR or return loss, phase length, and RF shielding. You know, how these properties change with time, temperature, flexure, you know, can be extremely important in many of the applications when it comes to antenna gain, things of that sort. You know, ironically,

many engineers don't understand that these properties can even change, let alone specify any kind of stability requirements in our source control drawing. So electrical stability is really what separates, I'll say, the best from the rest. Because there's many companies out there that are building 50 -ohm coax. But as you move up the food chain into what we call low loss or phase stable arena, that list of good suppliers gets real short.

making a high performing stable microwave cable is much more than just putting a braid or a shield on a dodger core. It requires significant design know -how, more exotic materials, precision processes, and that all comes at a cost. If you drill a little bit deeper into that stability question, the three stability that are most concerning generally are phase versus temperature,

IL change versus flexure and then phase change, I'll say with tight bending because usually when these cables get installed in the system, they all get routed to some pretty tight areas and take a pretty good beating. And nitro wave addresses all three of those. For phase versus temperature, for example, the amount of changes, the combination of the thermal expansion of the conductors and the density change of the doctrine. The good news for everybody really is that...

Judy Warner (07:10.936)
Mm -hmm.

Ron Souders (07:27.56)
These two properties tend to move in opposite directions. So the combined change is really less than either one would be by itself. There's not much we can do about the physics of the conductors. They are what they are. But lowering the density of the dielectric is proven to be significant in proving the overall phase change. And also, when you introduce some air into the dielectric, and we're talking for the most part, PTFE, polytetrafluoroethylene, part of the Teflon family.

It also improves the mechanical thermal stability, and these cables often see pretty large temperature extremes. And that results in less stress in the cable over the long term, which improves the reliability. For ILS stability versus flexure, that's highly dependent on the contact resistance change between the shield layers. And if it's a stranded center conductor, it also depends on the contact resistance between the strands. So maintaining low and now say consistent contact resistance.

on the shields is really the key to making a stable, IL stable cable. But that's made difficult by the fact that you're again, you're dealing with different thermal coefficients of expansion between the conductors and the polymers, fluoropolymers. Because the dodger, because we introduced air into them to improve other characteristics, they tend to be a little bit softer, making, keeping the shields around them tight and maintaining that low contact resistance. So it's a delicate balance between the amount of tension you apply when you're putting the shielding on the...

coax against the amount of compression you want to put in dielectric. You compress it too much, you squeeze all the good properties out of the dielectric, so to speak. And of course, any dirt or oxide on these conductors are going to create problems. So to ensure the stability of each nitrowave cable lot gets tested for stability after being thermal shocked. And the thermal shock is pretty extreme, minus 65 to 125 degrees C.

And then shake, literally put on a shaker table while it's connected to the analyzer and we're checking the electricals and looking for change. And for example, on the IL, the intenuation, we hold ourselves to a 5 % maximum change during that, you know, during that pretty vigorous test. And the truth is, I mean, it's rare that you see more than 1 % change. You know, for face stability on that tight bending, yeah, it's mostly controlled just by the design itself and materials. And something I haven't mentioned, you know,

Ron Souders (09:53.064)
You don't have a cable assembly without connectors. And on the connector side, the center contact captivation is real important to maintaining stability. So the key is, of course, to optimize each of those without sacrificing mechanical robustness or other electrical properties. So prior to release of each nitrowave part number, we go through an extensive battery qualification testing. So part of which is all the other.

Judy Warner (09:56.57)

Ron Souders (10:20.584)
stability test we didn't talk about and that test report of course is available to our customers upon request. So I was going to stay on a little long window here but to sum it all up, being the best in class for electrical stability is really a combination of design, things like that extra layer that we put inside the, between the braid and the shield, the material selection, the process controls, and some pixie dust. Of course I'm kidding on the pixie dust but there are.

There are some proprietary things that we don't want to share just in case any of our customers are listening. I'm sorry, customers. Competitors are listening. Customers could listen.

Judy Warner (11:02.458)
So I know that when I hear you talking, I'm being thrown back to my days in RF PCB fab. It's like the same story. It's the Teflon, it's the materials. And we used to always say, it's not complex, but it's extremely difficult to get all those things to line up and play well together and not sacrifice one for the other. It sounds that.

That is even more true inside cables and the connectors. So you've got those two pieces. So, you know, high performance, low loss cables have been around for a while. So what, besides the stability piece, which sounds like the most significant piece, what's driving it? And then I'm really curious to know.

Is it Mel Aero? Is it space? Is it AI applications? What's driving it and what other things besides stability is sort of driving the work that you both do? Dan, you want to tackle that one?

Dan Birch (12:04.695)
Yeah, sure. It's a great question. And, you know, there's so many different ways to answer, but starting at a high level, you know, a 10 ,000 foot level, I'll say what's changing is the complexity of the systems. You know, frequencies are going up as new spectrums are open, being opened up for applications and complexity in terms of the number of channels involved. You know, we're switching from, you know, 20, 30 years ago when you had simple.

transmit channel, receive channel in the realm of phased arrays where you have many channels that need to work together once. But going down at a more micro level, the complexity, I think maybe I'll just give you a couple examples. And the first one I'll start with high speed digital test. And that's one that really resonates well with Samtech since we're also selling

so many high speed digital products. So we get sometimes an early look at some of the test challenges that those customers are looking at. And one of those test challenges right now is testing 224 gigabit PAM4 systems. So even though those systems are moving signals differentially, at the test and measurement level, they still like to use single ended vector network analyzers and they have to come in with coax.

And there's work being done right now. I think they're honing in on what's needed, but there's still some debate by IEEE in terms of, you know, those coax cables that you come into to launch the signals into the test setup, they need to be delay matched. Or, you know, you often hear the term skew matched. And they're trying to decide right now how tightly do they really need to maintain that skew.

And even though they don't have an answer, you know, we have customers that are saying, okay, even though we don't, we don't know the answer. So can you just give us. Match match cables within half a peek a second. And, uh, that's very, very challenging. Right. And so, uh, we're doing it, but to make half a peek a second phase match cables with a good yield, you really need consistency on your raw cable.

Dan Birch (14:27.661)
And that's where you know Ron mentioned testing every lot of cable hopefully, you know Well, I know we get stability within a lot, but it makes a lot a lot easier if you know the lot you manufactured Next week it performs very similar to the lot you manufactured the week earlier because when we're making cable assemblies out of it, you know, we can't afford to start Completely over with every new lot of cable

So that's a good example where delay match is really important. Ron mentioned phase versus temperature. When you're talking about phase, phase and delay are kind of analogous. It's just the differences, typically a time domain versus a frequency view point on that.

Judy Warner (15:16.154)
Okay, hold on. Let's start with the phase and time domain sentence and I'll stitch it together.

Dan Birch (15:23.653)
Yeah, okay. Yeah, so the phase, when we're talking about time delay matching of these cables, it's kind of analogous to the phase matching that Ron's been talking about phase versus temperature and phase change versus bending. You're really talking about the same thing. It's just that people that work in the time domain with digital signals tend to talk about delay and frequency domain measurements. We're really just measuring phase, but it's that same.

you know, process control that gives us phase stability on the cables is going to allow us to give good delay control, time delay control for those test applications.

Judy Warner (16:08.602)
I spend a bit of time in the mill arrow sector and I'm sure that you know some of the testing you're doing, Ron going from very low temps to very high temps probably has applications there. So can you talk a little bit about maybe your successes in that space or how these cables fit into maybe your mill arrow customers?

Ron Souders (16:36.648)
You want to take that one Dan?

Judy Warner (16:39.354)
Hold on, we didn't really talk about that, did we? Or did we? Sorry.

Dan Birch (16:39.685)
Yeah, sure.

Ron Souders (16:43.208)
No, but Dan has a better idea on the applications that we're targeting than I do.

Judy Warner (16:47.802)
Okay, I'll ask the question a little bit differently, because I just see it at the list and I'm like, okay, we did channel, we did this. So I'm going to ask you about mill arrow because we do have a lot of mill arrow people. Um, so I want to talk about, um, those applications. So let me ask the question differently. Um, Dan, in addition to all the things you've talked about, because I have a background working with.

Ron Souders (16:50.022)
All right.

Dan Birch (17:06.213)

Judy Warner (17:16.518)
Mill Arrow, which is really can be really difficult as far as the environmental challenges they have. So what's your observation about this performance, whether it be thermal or matching signals at a very precise like, where are you guys in regards to Mill Arrow applications and the specific things they need?

Dan Birch (17:43.781)
Yeah, well, that's a great question also. And I'll say that, you know, most people know that, you know, there's always been a lot of microwave work on military aerospace. In fact, you know, the military aerospace world probably funded a lot of the very forerunners of coax and coax connectors and all that for some of the early radar systems. And to this day, no aero market relies heavily on RF and microwave.

components. Now, you know, let me start with what hasn't changed is those those temperature changes, or temperature extremes where Ron was mentioning, you know, the thermal shock minus 65 plus 125. That that hasn't gotten any easier, right? That those temperature changes are typically related to the variations in temperature that an aircraft would see, you know, going from say a hot desert runway.

up to high altitude, you know, 60 ,000 feet where it gets that cold. So that's not changing. What is changing, you know, if you're, if you're watched around, you know, we're changing from the days of having individual large aircraft into this day of squadrons of small drones where you see there's the systems need to see the same, you know, temperature extremes, that same harsh environment. But now to make it economical and be able to field.

Judy Warner (18:47.866)
Mm -hmm.

Judy Warner (19:01.282)

Dan Birch (19:12.101)
these squadrons of drones, you know, everything's gotta be lighter, smaller and cheaper. So you gotta be able to deliver the performance with smaller cables, lighter cables and you and you also got the high frequencies coming in. So to give you a, you know, yeah, right. Yep. And then a, you know, a real interesting application that,

Judy Warner (19:30.106)
Yeah, good old swap, right? Does not get any easier.

Dan Birch (19:40.741)
I've recently come across or the military electronics manufacturers are working on these things called multi -mission configurable arrays. And what these things are, it's essentially a programmable phased array transceiver. And it's kind of like software defined radio on steroids. So you say like, well, what does that mean in terms of cables? Well,

Judy Warner (20:03.674)

Dan Birch (20:09.285)
What they're trying to do here is make a very configurable system that can be used for many different missions. Could be a targeting radar, or it could be a comm link, or maybe it's even a radar jammer. But that same base system, the idea would be capable to serve any of those missions, but just changes in programming. But to do that, the hardware horsepower under the hood, so to speak,

Needs to be powerful in all ways the digital signal processing has to be super powerful But also the RF power sections of those systems need to be powerful as well They need to therefore, you know the cables we need to watch our cable losses so that we're not wasting the precious power It's phased array so we got to make sure that our channel to channel phase variation or delay variation again stay within bounds so that's you know,

Ron Souders (21:04.424)

Dan Birch (21:04.665)
Those type of systems are just sort of driving the performance needs of all RF interconnects to higher levels of performance. I think that's a pretty cool application. I know it's not going to be easy, but it's one we're looking at.

Judy Warner (21:16.986)
Very cool.

Judy Warner (21:22.554)
I have many more questions that we're going to be able to cover. And the more you gentlemen talk about this, the more, but I'm going to try to control myself a little bit. So I know with the high speed digital side of Samtech, because I've gotten to know several of your internal SMEs, they've talked about the unique thing that they offer, which is not only, you know, off the shelf products, but also that they custom configure.

things like the application you just spoke about. Is that something you're looking to do or that you that you are actively doing? How does that work?

Dan Birch (22:02.373)
Well, we absolutely like -

Custom applications is a big part of Samtex business. But the way we like to handle it is instead of sort of customizing everything on the fly, which would be very risky, we try to get the building blocks right. So we figure if we've got the right building blocks of connectors and we've got the right building blocks of raw cables, then if a customer needs a slight customization, like maybe they need a different jacket material on the cable,

you know, for radiation resistance or something like that. Or they need a lower profile connector to fit into their system. You know, now there's less risk because we're only making sort of small changes to one or two components rather than redesigning the whole ecosystem, so to speak, from scratch.

Judy Warner (22:59.354)
What a great name. It's almost like so much to do a podcast.

Dan Birch (23:02.661)

Ron Souders (23:03.336)
Yeah, I would actually, I would call it almost like custom configurable, right? You have the components laying around and everything about microwave RF application, there tends to be sort of logistically complex, a lot of sort of customization. And actually the companies that do quite well are the companies that can, I'll say, customize that solution quickly. And of course, you know, accurate.

Judy Warner (23:09.25)
Mm -hmm.

Judy Warner (23:28.314)
I think that's great, especially for, you know, as fast as our industry changes and the speed and frequency demands just never slows down. So I think it's very interesting. So I know you guys are going to be showing off some of these cables at IMS. So why don't you tell us a little bit about that and then what's next for you two? It sounds like none of this R &D and innovation is stopping.

Dan Birch (23:54.341)
Okay, yeah, IMS, you know, that's coming up in June. If you're gonna be in the Washington, DC area, I would encourage you to make sure you get in there. We're gonna be at booth 1531, and we're obviously gonna be showcasing nitrowave cables. You're gonna find those cables on most, if not all of our Samtex product demonstrations at the booth. You'll know it by the orange color. And then I think you're also gonna find, you're gonna see some orange cable.

on some of our partners demos at their booths as well. So that's really exciting. We're looking forward to that. If you're not gonna be at the show, go to our website, samtech .com slash nitrowave. We've got a dedicated page up where you can find specifications. Initially, you're gonna find information on the LL043 cable and the LL071 cable. And then you'll see information on the rest of the family of

Night Wave popping up as we progress through the rest of this year.

Judy Warner (24:59.322)
So Ron, I'm going to let you wrap up with sort of a personal question. When you guys started in this industry, you know, as two green horns, did you ever think that you'd be at the speed and technologies and what has that right been like?

Ron Souders (25:17.)
Absolutely not. I was sort of, I'll say fortunate just to get in the RF industry to begin with because I did well in RF and not so well in the active circuit type stuff in college. So it was a blessing when I landed here. Yeah, and just in the last couple of years, the speeds have gone exponentially higher, right? And we actually, Dan and I worked on a project back with about 2000, right? We were...

We were making a little semi -rigid twin ax that would have worked real well in these high speed applications. We were about, you know more about the digital than I do, Dan, but it was probably about 20 years ahead of its time.

Dan Birch (25:59.429)
Yeah. Yeah. Well, unfortunately it was, we were finishing it up right at the dot com bust that and, and that was the end of that.

Ron Souders (26:04.2)
Yeah, that was it.

Judy Warner (26:04.866)
Oh yeah, that's what fun times. Yeah, fun times. It's amazing. We all lived through so many iterations of this industry and technology. Well, thank you both. It's been so interesting learning from you and learning about the complexities of these cables and 70 and really the enablers. So, um, for our audience, I am going to put links to all the things that Dan and Ron discussed below and, um,

Ron Souders (26:08.104)

Judy Warner (26:32.76)
Like Dan said, if you're going to be at IMS, I'm going to be there. Please stop by their booth and look for those orange cables and you can learn more. And I hope this will help you find solutions that will work for your products. Gentlemen, thank you again. It's been wonderful to meet you and to learn about your journey and all that you're doing at Samtech.

Ron Souders (26:49.096)
Thank you.

Dan Birch (26:55.045)
Thank you, Judy.

Judy Warner (26:58.554)
For this, thanks so much for joining us this week. We will see you next week. Until then, remember to always stay connected to the ecosystem. That's a wrap, gentlemen.