Does anyone know how you worked out the trace width and separation of the monopole antenna used in DN024? Also, what is the reason for having the monopole on both sides of the board stiched together with vias?
I'm thinking of experimenting with a narrower trace with smaller air gaps, to save space. I've done some experimentation and found that a) I need a longer trace and b) I need to do some impedance matching even at resonant. I have not tried putting the monopole on both sides and stitching it with vias.
The dimensions of the antenna was derived from simulations. The original antenna, as shown in design note DN024, is single layer. The dual layer version found in the Antenna Selection Guide was made by Richard W. If I remember correctly the benefit of the dual layer version is wider bandwidth (simplifies tuning) and also dual band functionality for 2.4GHz use as well.
Feel free to play around with the geometry, and do let us know if you make any improvements to the design!
--PS. If I answered your question, please hit Verify Answer !
Someone just verified this answer, so I thought I'd write down what I found.
My board is pretty small. Its ground plane size is less than a quarter wavelength. I experimented with meandering monopoles with various trace widths / air gaps: 0.635/0.635mm, 1/1mm, 0.635/1mm, 2/3mm. All of them were on both sides of the board switched together with vias. 2/3mm looked best on the VNA. I matched all of them and tested their range in a field. 0.635/1mm was actually a little better than 1/1mm, and 2/3mm. I expected 2/3mm to win because of its size. I can't explain the results. I have an antenna, though, that works as well as chip antennas of similar size and is only a few dB down from an eval board with rubber duck.
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