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RF PCB design. Need for some impedance software calculator

TomB11
Intellectual 265 points

Hi,
I am designing 2 layer PCB in Eagle for frequency 169MHz. (Antenna will be connected via SMA connector, there will be also PA from Skyworks). Are there some programs, software for impedance calculation?
Could you recommend some?

BR,

Tom.

  • 0
    TI__Guru**** 317180 points
    There are plenty of calculators online, here is one:

    http://chemandy.com/calculators/microstrip_transmission_line_calculator.htm

    Normally all EM simulators also have one built in.
  • 0 in reply to TER
    Intellectual 265 points
    Sorry I forgot to mentioned. Those calculators:
    - [the one you point]
    - http://emclab.mst.edu/pcbtlc2/microstrip/index.html
    - http://www1.sphere.ne.jp/i-lab/ilab/tool/ms_line_e.htm
    - http://www.eeweb.com/toolbox/microstrip-impedance
    - http://www.emtalk.com/mscalc.php?er=4.8&h=31&h_units_list=hmm&f=0.169&Zo=178.600230512&EL=7.33903644725&Operation=Analyze&Wa=55.5003355853&W_units_list=Wmm&La=2&L_units_list=Lmm

    provide impedance based on tickness of FR4 laminate, width and hight of trace. (this I have already done).
    I would like to calculate distance on top layer between trace and ground plane on top layer. I think this distance has a significant factor on impedance.

    Thanks,
    Tom.
  • 0 in reply to TomB11
    TI__Guru**** 317180 points
    I think this one should do the trick:
    http://www.awrcorp.com/products/optional-products/tx-line-transmission-line-calculator
  • 0 in reply to TER
    TI__Guru**** 317180 points
    Btw, on 169 MHz the wave length is fairly long. Or in other words, no lines on the PCB will be long enough to behave like a transmission line so using a calculator will not give you much. If you want to do a 2 layer design giving 30 dBm out you have to be really careful with the ground connections etc.