Texas Instruments: Antenna selection quick guide
Here’s an antenna selection guide from Texas Instruments. What we find interesting are the various comparisons of 2.4 GHz wireless antennas and the linked documents which describe how to design them.
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Here’s an antenna selection guide from Texas Instruments. What we find interesting are the various comparisons of 2.4 GHz wireless antennas and the linked documents which describe how to design them.
Alfredo Alcazar:
February 24th, 2013 at 11:32 pm
The information is very interesting.
Alan:
February 25th, 2013 at 10:53 am
Bad luck for anyone working under 100MHz
KH:
February 25th, 2013 at 12:17 pm
Just recently there was a posting here about using headphone wires for FM reception. That’s your integrated 100MHz antenna. Saying “back luck” is just as bad as Steve Jobs saying that you’re holding it wrong. Study some EE; no need for luck.
AMS:
February 25th, 2013 at 3:12 pm
Magnetic loops (think broadcast AM radio) work pretty well for things under 100MHz. You’re never going to get a great integrated antenna at those frequencies though because the wavelengths are huge.
Alan:
February 25th, 2013 at 11:01 pm
If the TI article had bothered to reference your headphone-as-antenna idea, I’d agree.
Heck, if they’d just bothered to give some generic dimension vs frequency equations I’d be happy.
KH:
February 26th, 2013 at 12:20 am
The last row already gives the obvious hint. Just look for quarter wave monopole, tons of stuff if you just look around, even Wikipedia has a big list of antenna types. A helical antenna is shorter, and look at the last row, most are helicals. Steel springs is stronger than copper, and for large antennas under 500MHz, most would not use up PCB area to mount it. Toy walkie-talkies usually use cheap helicals.
And if you had actually look at DN031/SWRA328, the doc points you to SWRA161, which has some theory and lots of diagrams. But for non-simple shapes, there are few equations and you’d need to model the antenna or measure it. So no problem if one actually put in a little effort…
ee:
February 26th, 2013 at 12:37 am
I looked at this PDF yesterday, however I couldn’t see if they stated all the details for the helical antennas like diameter, length and turns (although all this could be deduced from the silkscreen outline).
Did I miss it?
Also, they didn’t specify wire gauge – I suppose it doesn’t matter, much like inductors?
Thanks!
KH:
February 26th, 2013 at 1:40 am
Some variables matter a lot less than others. Dimensions much smaller than the wavelength has little effect on radiation pattern. But impedance should match etc. Hard to make a “best design” via equations alone. But even random wires work to a certain degree and have been used in many applications, e.g. for FM radios, or power lines used for TV reception. It all depends on your app. For hobbyists, antennas are widely available where reliably good performance is demanded, else we can eschew perfection and tinker, which is great, but don’t expect miracles.
ee:
February 26th, 2013 at 11:41 am
Thanks, that’s good to know. Yep, I’m a hobbyist, so for some upcoming projects (zigbee and wifi) I was just planning to follow manufacturer existing antenna recommendations and just purchase ready-made antennae, and if I get bolder one day I may try to just initially replicate some designs because I don’t have the knowledge (or test gear) for advanced tests, and from what you’re saying I should worry more about the larger dimension parameters, not <<wavelength. For lower frequency (HF) stuff I've been assembling a VNA but it's taken a long time, and until I get to the point I can power it up I've no idea beyond some basic theory what to expect. Other test gear I have is limited to just conventional scope, a low-GHz spectrum analyzer, some receivers and VCOs.