Antenna tunning/ matching circuit
A_neves , 11-11-2019, 07:11 AM
I want to produce a device with Bluetooth and GPS, so I need to place an antenna on PCB (ceramic or PCB antenna).
I know that there is a matching circuit to tune that. How can I tune that to properly work on that frequencies?
ypkdani , 11-11-2019, 02:09 PM
for design an antenna, or place a ceramic antenna, on your pcb you need to:
- have a region where to put that, normally without ground plane around or on the other layer down that
- if you use a ceramic antenna you need to follow the application note that explain you ho to match the antenna an how to design the pcb around that
- if you design the antenna normally you find some application note from TI or other manufacturer that had already design that
following that indication you normally can reach a good cover range. If you want to obtain the optimal result you need to try, normally starting from some passive component indicated in some sample. From that you can use a spectral analyzer with a directional coupler (ex: http://wireless.ictp.it/handbook/C6.pdf
Design a good antenna normally is not simple because all the things around it influence it, and you need some basic instruments (for first a spectral analyzer), so in my projects i had used ceramic antenna
A_neves , 11-12-2019, 05:02 AM
Thanks for your answer @ypkdani .
I know that if we use a pi matching circuit for the antenna, we can tune that components for the right impedance.
My question is how can I do a right measure of the impedance, what is the procedure?
There is some techniques?
ypkdani , 11-12-2019, 05:19 AM
For tuning an antenna you need to set up a test like this in the video: https://www.youtube.com/watch?v=k2VVtKaysLo
. You need to start with some passive values (taken from some reference sample), take the measure and the try to change they. When the resonance reach the better result you have matched the antenna.
A_neves , 11-12-2019, 08:28 AM
@ypkdani do you think that with a ceramic antenna is easy to make a device communicate properly by following manufacture instructions?
ypkdani , 11-12-2019, 08:38 AM
Yes becuse normally you have a design guide to follow and the passive values for have a correct matching.
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