Line of Sight
Antennas Get No Respect

Antennas Get No Respect

You can’t have a successful wireless product without a good antenna. Of course, you know that. You must have that small bent piece of metal to connect your radio to the ether or nothing will happen.  I still am amazed at how such a seemingly insignificant mechanical device actually translates the wireless power into the electromagnetic waves that carry the information to be transmitted. Also, it seems to me that the antenna is the stepchild of any wireless system. It gets less attention and may even be an afterthought in some projects. But as you may have noticed, the antenna is becoming more important than ever in new wireless systems. It’s time to pay more attention and give more respect to what may really be the most complex piece of any new wireless system.

In the past, a radio could perform nicely with a simple half-wave dipole or quarter-wave vertical. And there are still a few applications where a PCB meander line or loop will get the job done. Such antennas will still be with us, but they are just not good enough for the newer wireless systems such as 4G and 5G cellular, as well as some military and industrial systems.  For example a smartphone antenna must not only fit into an impossibly small space alongside GPS, Bluetooth, NFC, and Wi-Fi antennas but also must have wide bandwidth and a low SWR over multiple cellular bands. Can you design one of those antennas?

But that’s not all. Most 4G and all 5G cellular radios use MIMO. So, multiple antennas are needed. The 1×2 and 2×2 MIMO configurations of 4G will give way to massive MIMO with configurations like 8×8 for 5G. In addition, 5G will undoubtedly use millimeter waves. The good news is that the antennas will be small, but multiple elements will be a necessity. Phased arrays will be needed to provide the gain to offset the lower power devices in the radios. And most 5G systems will typically use adaptive beam-forming and steering antennas to prevent all those small millimeter wave cells from interfering with one another while providing the needed gain to make the whole thing possible. As it turns out, the whole future of 5G depends heavily on new and better antenna technology.

The final frontier of wireless is antenna design. It is time to learn more about antennas and give them their due. I used to think that only real RF engineers designed antennas, but that may no longer be true.  Antenna design has become so complex that today they are mostly designed only by those who specialize in this black art. As an RF system designer, you will probably buy rather than design your own antennas.

That should not keep you from learning more about this essential subject. What brought all this to my attention was a new book entitled Foundations of Antenna Engineering, A Unified Approach for Line-of-Sight and Multipath by Per-Simon Kildal, published by Artech House. It contains 11 chapters of the latest antenna design information. The book reviews essential fundamentals and gives a great coverage of multipath and brings together the multiple disciplines of electromagnetic theory, classical antenna theory, wave propagation, and antenna system performance. The author is even offering a MATLAB handbook to provide initial antenna designs. If your antenna knowledge is out of date or otherwise lacking, this is a good book to bring you up to speed.  Even if you won’t be doing your next antenna design, at least you will understand what you are facing in new wireless projects.

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