When product engineers are designing wirelessly enabled products—by adding wireless features to previously unconnected, or build “smart” products from scratch—it’s easy to get lost. The world of embedded antennas is a complex maze where it’s easy to get overwhelmed, disoriented, and discouraged. There are thousands of antennas to choose from if you scroll through a typical distributor’s website. Factor in wireless modules with embedded antennas, the number is higher.
My goal is to demystify the world of antennas, for when it’s time to choose the right brand for your product. With just a few tricks of the trade, you can navigate through the antenna selection process more efficiently and with more confidence that you picked the right antenna for your project.
The first step is take back your power in this process by being skeptical about what marketing information and data sheets say about each antenna. Although data sheets and specs on antenna product pages look like a litany of facts, the reality is a lot of marketing goes into how these antennas are presented to engineers.
It’s in the best interest of antenna manufacturers to make each of their products appeal to as broad an audience as possible. This means you as a product engineer must be skeptical of what they are putting up front, and peer around the back at critical information that will tell the full story. Healthy skepticism will encourage you to look at details that marketing folks are purposefully trying to distract you from, or are unavailable in data sheets.
Spec sheets for antennas are ultimately sales materials, where facts and figures are put through a marketing process before ending up on the page. That alters how their presentation, what is put up front and back, along with how much the numbers were presented in the best possible light through advantageous testing environments.
Don’t Trust the Range
What are specific ways you should put that skepticism to work in evaluating antennas and modules? You first must ignore any number you see in data sheets about the antenna’s range. I know that’s asking a lot because the range is often the very first detail an engineer will seek when looking at antennas. Manufacturers know that too, which is exactly why that number is typically unreliable information.
Are manufacturer’s lying? Sort of. They’re telling the truth in that they (probably) attained that range number someway. What they don’t tell you is how they got the number. Too often, they do that by utilizing a testing environment with a night-and-day difference to the real world. Having this skepticism will help avoid the lure of marketing language that makes some antennas look attractive when they aren’t a good fit.
Look Closely at Return Loss…and Testing Information
Antenna data sheets that share detailed Return Loss information are worth their weight in gold because those number give you important information about how the antenna actually works. Inclusion of Return Loss data is also a good sign the manufacturer believes in the product and is willing to share performance statistics that many manufacturers try to bury.
Another sign you can put trust in a data sheet is when manufacturers shed light on the testing process by sharing information on how the test was conducted, shielding that may or may not have been used, what kind of materials were in the antenna’s vicinity during testing, etc. Each of those reflect a real effort on the manufacturer’s part to:
- Have transparency about the testing process
- Replicate real-world conditions rather than hide behind idealized testing environments
- Equip the engineer with as much information as possible to facilitate a good decision
Details Return Loss information, transparency about testing scenarios, and an obvious effort to be informative rather than obfuscating will help you make smart, quick decisions on how to narrow down these options to a reasonable number.
Look Closely at Power Consumption
For so many of the design projects, battery life is a critical issue. Whether it is IoT-enabled devices running on batteries or portable consumer devices, battery life is important. It’s also worth noting one of the biggest drains on batteries is how much power antennas and wireless modules need to stay connected.
While range is a data sheet’s most misleading metric, power consumption is a close second. Marketers can make power consumption look dramatically better than it truly is by using specialized testing techniques. Too often those power consumption numbers are practically fictional based on the way tests are conducted. Once you have a short list of prospective antennas/modules, the key is to get test units in your hand and run trials under real-world conditions to understand their actual battery consumption.
No issue creates end user dissatisfaction faster than poor battery life, so this is often a do-or-die factor for the success of a product. Product designers need to have trustworthy power consumption numbers, which you unfortunately won’t find in data sheets and marketing materials for antennas and modules. The only way to get an authentic number is to test a shortlist of candidates yourself, and compare how well they fit your product’s needs.
Take the Time to Test
Some people mistakenly think it takes a high-end lab environment and testing room for modules and antennas, but that’s a misconception. Testing allows you to put antennas and modules in real world scenarios like placing wireless equipment inside the material the product will be made of, or placing it near other components that may reflect, shield, or distort signals.
One of the most important benefits of testing isn’t simply to verify key numbers in the data sheet, but testing can be eye-opening in other ways by shedding light on the fact that many of these models require additional modules, peripherals, and materials in order to be fully functional. By getting a sample unit in hand, you can often learn the full scope of what you need in order to add wireless connectivity to a product. This information also factors in product’s cost structure, allowing engineering to avoid being surprised by the cost of additional components they didn’t realize were needed until after the matter.