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imp.guru Droplet and 915MHz Long Range Radio to WiFi


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Sorry for the mega post but as you may have already noticed, lately I

This is wrong.  I won't get started about HAM and ARRL, and how they destroy innovation in the modern era.  But at least you can figure out my opinion.   Lower wavelengths represent smaller particle

One common mistake is to assume that such a thing as a 1/4 wave resonant antenna exists.  The truth is, there must be a 1/2 wave dipole, or you must have a ground plane acting as a counterpoise to you

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@@jpnorair were you referring to the antenna design like on page 64 of this app note:

http://www.silabs.com/Support%20Documents/TechnicalDocs/AN782.pdf

 

What are your thoughts on silicon labs EZradio PRO like the one in Si1064?

The antenna on page 64 (marked as 62) is a quarter wave IFA. This is actually similar to the antenna in the HayTag, except there are some other techniques used to increase the "electrical length" and to improve the size of the ground plane. Too much to explain.

 

The antenna I mean by "omni-dipole" is different. It is just a vertically oriented wire dipole antenna. I usually use a dipole with a big inductive load (i.e. a helical element on each arm) in order to reduce the size. The penalty is bandwidth, but this isn't usually a problem for 433 MHz or 868 MHz usage. For 915 MHz band, it's OK if you are using the DSSS option of FCC 15.247. For frequency hopping option, you need to worry about bandwidth.

 

Finally, I have not personally tested the Si1064, but on paper I'm not crazy about the EZradio or EZradio PRO devices. In the antenna test ddocument, I would also like to know more about their test criteria. Saying "outdoor" is not enough. I am guessing they did a test with one or both of the nodes mounted high on poles to reduce ground interference, which is a major form of attenuation.

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