Videos / Antenna Design: Custom vs Off-the-Shelf

Antenna Design: Custom vs Off-the-Shelf

Several considerations must be taken into account when implementing antennas: mechanical constraints, special requirements, EAU, NRE, schedule, risk, etc. Dustin Morris, Digi Antenna Engineer, shares the primary factors that determine whether custom or off-the-shelf is the right antenna solution.

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Mar 30, 2016
3:10

Show Transcript

Hi, I'm Dustin Morris. I'm an Antenna Engineer at Digi Wireless Design Services and I'm going to talk to you today about custom antennas versus off-the-shelf antennas, and hopefully give you enough information that you can make the right decision on your next wireless product. So when we first do our consultations with customers, we ask them some key questions to try to figure out, what is the right antenna solution? So those questions are, what's the application?

So is it GPS, cellular? Is it body-worn or or is it a vehicle telemetry device? What's the form factor? How small is the device for the mechanical constraints? EAU, what's your Expected Annual Usage? Are you planning on shipping 1,000 units or 100,000 units? And that's going to come in handy when we're doing ROI calculations for our custom antennas. And your priorities. So what's most important to you? Is it schedule, performance, certification risk, or NRE costs?

Why would you use an off-the-shelf antenna? Well, if you're doing a proof of concept or you need a quick development cycle, you're going to want to use an off-the-shelf antenna because it's easy to source, it's readily available, you can go and buy it today. Why else would you want to use an off-the-shelf antenna? Well, low risk. And the question mark. So why is there a question mark? Well, an off-the-shelf antenna is low-risk as long as your PCB ground plane is very similar to the ground plane of the manufacturer's evaluation board. So why would we want to use a custom antenna? Well, your application may have some special requirements.

You might need GPS and Wi-Fi and cellular all in the same antenna for a given application, so you're not going to find something like that off the shelf. So if you need special requirements that aren't available, then you got to go custom. Wearables. So body-worn antennas are...typically you're going to see better performance with the custom antenna that's designed to perform well in that situation. Most off-the-shelf antennas will not perform well when body-worn. And then your custom form factor.

You might find that you can't find an off-the-shelf antenna that's gonna meet your performance requirements and your mechanical requirements at the same time. And in that scenario, you're going to need a custom form factor. So maybe you need a low-profile antenna like a PCB trace antenna that's etched directly on the board, a stamp metal antenna, or a flexible printed circuit antenna. Why else would you want to use a custom antenna? If you have high volumes.

The custom antenna is going to be the lowest-cost solution. So as your volumes get over, say, 10,000 pieces per year, a custom antenna's going to make a lot of sense and you're going to see a return on your investment of less than one year...is what we like to see. And low risk. So I think custom antennas provide the lowest risk possible, because you're going to simulate and design the antenna, then you're going to build, test, and tune that antenna before you ever finalize your mechanicals or your industrial design. So you're going to have antenna metrics before you really build anything, and you're going to know if you're going to meet regulatory approvals or carrier approvals. So you're going to have the lowest-risk path by going custom.

I hope that gives you a brief overview of some pros and cons of custom versus off-the-shelf. And you can find more information at www.digi.com/wds.

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