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Rf Antenna inductance&impedance

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  • Rf Antenna inductance&impedance

    Hello, I want to design an RF antenna. I am using TRF7970 IC. I want to design my own antenna. I can calculate the inductance value of the antenna. But I don't know how many ohms the antenna is impedance. Is there a need to calculate impedance for the antenna? Otherwise, I will find a balance with the capacitor and resistors determined in the Q circuit in the photo.
    In summary, I can calculate the inductance for the antenna. However, I am not sure if it is necessary to calculate impedance.
    I am waiting for your suggestions on the subject.
    Thank you.
    Attached Files

  • #2
    I am based on the values entered in the TI source document. When I calculate the standard single ended 50R impedance of Altium, it is not 50 ohms. Should we use a different calculation method?
    Last edited by suleymancskn; 11-03-2020, 02:52 AM.


    • #3
      I am not RF expert. However I can tell, that every single software where I try to calculate impedance will give me different results. Of course, the results should be similar, but they are never exactly the same - that is the reason why I trust the numbers which are provided by the PCB manufacturer.

      In your case, to route 50OHMs I would try to ask PCB manufacturer for their recommendation. If it is not possible ... then I usually go with the free Saturn PCB Toolkit calculation:

      PS: I do not know how accurate is the Altium calculation. I do not trust any Altiums calculations as they just keep changing everything (including calculations). But I need to add, that when I checked Altium impedance calculations last time, they were close to what I was getting also in different software.


      • #4
        Hi Robert,
        I agree with you. Better to get impedance details from PCB manufacture, its makes life easy.