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How to match an antenna for a proper current comsumption

Question asked by Gutierrez.David on Jan 3, 2017
Latest reply on Jan 9, 2017 by Henry Crane

Hello,

I have a CR95HF chip and I would like to set the TVDD power consumption to set a certain battery lifetime in my system. I used the excel tool to set a proper impedance and the formula to calculate current drained from VPS_TX. The problem is that they do not match.

 

I measured the impedance of my own antenna with a miniVNA-pro net analyzer. I used the Excel tool to calculate L0, C0, C1 and C2 values for a 27ohm impedance and I assembled tem. The problem is the final measured impedance of the matching+antenna set was ~51ohm. Also, the current measured at VPS_TX was about 37mA, value that corresponds to a impedance of aprox 78ohm.

 

Since anything is giving the values expected, what should I take as a valid result? How can I measure the final matching+antenna impedance?

 

Thanks

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