When product engineers are designing wirelessly-enabled products (by adding wireless features to previously unconnected products or building “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. There are literally thousands of antennas to choose from on a typical distributor’s website. If you factor in wireless modules with embedded antennas, the number is even higher. With just a few tricks of the trade, you can navigate through the antenna selection process more efficiently and with more confidence that you have picked the right antenna for your project.
Be Skeptical
The first step is take back your power in this process by being skeptical about what the marketing information and data sheets say regarding 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.
It’s in the best interest of antenna manufacturers to make their products appeal to as broad an audience as possible. this means that you as a product engineer need to be skeptical of what they’re putting up front, and peer around the back at critical information telling you the full story. Having a healthy skepticism will encourage you to look at details the marketing folks are purposefully trying to distract you from or are unavailable in the data sheets.
I am an engineer and sometimes fall into the trap of thinking the rest of the world operates in a way where facts are facts and data sheets should be a place where they take precedence. The reality is spec sheets for antennas are sales materials first, where facts and figures are put through a marketing process before ending up on the page. That alters how they’re presented, what’s put on the front, back, and how much the numbers have been presented in the best possible light through advantageous testing environments. Skepticism will be your best ally in finding an antenna that’s truly right for your project.
Don’t Trust the Range
What are specific ways you should put that skepticism to work in evaluating antennas and modules? The first step is ignoring any number you see in data sheets about the antenna’s range. That’s asking a lot because range is often the first thing an engineer’s eyes go to when looking at antennas. Manufacturers know that, which is exactly why that number is typically the least reliable information.
Are manufacturer’s lying? Sort of. They’re telling the truth in that they probably somehow attained the range number. What they don’t tell you is how they got the number. Too often, they utilize a testing environment having a night-and-day difference with the real world. This skepticism will help you avoid the lure of marketing language that makes some antennas look attractive when they actually don’t fit your needs.
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 numbers give you important information about how the antenna actually works. Inclusion of Return Loss data is also a good sign the manufacturer is willing to share performance statistics that many manufacturers try to bury.
Another sign you can put trust in a data sheet is when a manufacturer sheds light on the testing process by sharing information about how the test was conducted, the kind of shielding used, what materials were in the antenna’s vicinity during testing, etc. Each reflects 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 to facilitate a good decision
Details Return Loss information, testing scenario transparency, and obvious efforts to be informative rather than obfuscating help make smart, quick decisions about narrowing down options to a reasonable number.
Look Closely at Power Consumption
Many design projects readers of this magazine work on involve battery life as a critical issue. Whether it be IoT-enabled devices running on batteries or portable consumer devices, battery life is important and one of the biggest drains on batteries is how much power antennas and wireless modules need to stay connected.
While range is the most misleading data sheet metric, power consumption is a close second. Marketers can make power consumption look dramatically better using specialized testing techniques. With all apologies to my marketing friends, too often those power consumption numbers are practically fictional based on how tests are conducted. Once you have a short list of antennas/modules that you’re interested in, the key is getting test units in your hand and test them 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 a product’s success. Product designers need trustworthy power consumption numbers, which you won’t find in data sheets and marketing materials. The only way to get trustworthy numbers is testing a shortlist of candidates yourself and compare how well they fit your product’s needs.
Take the Time to Test:
The only way to truly know what you have in an antenna or module is to test a sample unit for yourself. Some people mistakenly think it takes a high-end lab environment and testing room, but that’s a misconception. Testing allows you to put antennas and modules in real world scenarios, like placing wireless equipment inside material the product will be made of, placing it near other components that may reflect, shield or distort signals, etc.
One of the most important testing benefits isn’t simply to verify key numbers in the data sheet like range and power consumption, etc. Testing can be eye-opening in other ways by shedding light on the fact that many antennas and modules require additional modules, peripherals and materials in order to be fully functional. By getting a sample unit, you can often learn the full scope of what you need for adding wireless connectivity to a product, which you can factor into the larger product decision. This information also factors into the cost structure for products, allowing engineering to avoid being surprised by the cost of additional components they didn’t realize they would need until after selecting an antenna or module.
