Balun FT140-43 7T Three Port

NOTE: All 3-Port CMR mesurements are off by +6dB
Due to a math error.



VNA Three Port Schematic


SimSmith Model and Four Measurements

  • ThreePortCMR Blue = Three Port CMR
  • ModelCMR Violet = Model CMR
  • TwoPortCmInCMR Red = Two port Input TL Sense Transformer
  • TwoPortCmLCMR Yellow = Two port Load Center Tap
  • TwoPortCmLTfCMR Green = Two port Load Center Tap Sense Transformer
  • All Files: FR43.zip
  • Three Port Fixture design and calibration notes
  • SimSmith Three Port Equation:
    ARRL Publication "Measuring HF Balun Performance" 
    //Plots
$s21 = Gamma(S21[]);
$s31 = Gamma(S31[]);
$sum = $s21+$s31;
$diff = $s21-$s31;
ThreePortCMR = 6+20*Log10(Mag($sum/$diff));




Balun Insertion Loss Investigation

  • FT140-43 7T 46uH at 10kHz (Measured)
  • Three Port fixture photo and description in above section
  • Files: FR43.zip
  • SimSmith input parameters:
    • A.file = Fair-Rite Complex Permeability file
    • A.k = Transformer coupling cofficient.
      Tuned for Model IL trace to follow diff/2 trace
    • A.mui= Ferrite Initial Permeability, μi
    • A.Hi = Initial inductance
    • A.T1L = Transmission Line length
    • A.T1vf,T1z,k0,k1,k2 = #20 Magnet with PTFE Sleeve (Measurement)
    • G.S21 = Three port fixture Port 1 to Port 2
    • G.S31 = Three port fixture Port 1 to Port 3
  • SimSmith Traces:
    • Model IL = Model Insertion Loss dB
    • 3Port diff/2 = 3 Port Fixture IL dB
    • 3Port sum = 3 Port Fixture Port 2 Port3 difference dB
    • Three Port CMR = 3 Port CMR computation dB
    • TwoPortCMR = 2 Port Fixture CMR measurement dB
    • ModelCMR = SimSmith Model CMR dB


SimSmith file SS-Balun-Model-3Port.ssx


Balun RUSE AG.Plt Text 
/Plots
$s21 = Gamma(S21[]);
$s31 = Gamma(S31[]);
$sum = $s21+$s31;
$diff = $s21-$s31;
Plot("3Port diff/2",20*Log10($diff.M/2)," IL dB",y2);
Plot("3Port sum",20*Log10($sum.M),y1);
dcl ThreePortCMR = 20*Log10(Mag($sum/$diff)*2);
Plot(ThreePortCMR);
dcl TwoPortCMR = 10*Log10(ISO1.P);
Plot(TwoPortCMR);
dcl ModelCMR=10*Log10(L.P);
Plot(ModelCMR,"CMR dB");




Balun FT140-43 7T TL CM

  • FT140-43 7T 46uH at 10kHz (Measured)
  • 16" #20 Magnet with PTFE Sleeve Zo=65Ω (Measurement)
  • Fixture Port 2 = Differential Mode In
  • Fixture Port 3 = Common Mode Out
  • FT50-43 1T:10T Sense Transformer
  • S2P Calibration using 50Ω Load through sense transformer
  • Fixture Balun Load = 50Ω with center tap ground
  • FT140-43-7T-TL-CM.s2p


TL CM Fixture Schematic


VNWA Common Mode TL CM Fixture CMR




Balun FT140-43 7T

  • FT140-43 7T 46uH at 10kHz (Measured)
  • 16" #20 Magnet with PTFE Sleeve Zo=65Ω (Measurement)
  • All Files: FR43.zip
  • VNWA Measured Common Mode Z at 14MHz
    Rs = 5640Ω
    Xs = 4321Ω
  • Computed Inductor Z at 14MHz
    Rs = 1480Ω
    Xs = 1150Ω


Fixture Schematic


VNWA Common Mode Fixture CMRR


SimSmith Balun Model and VNWA Common Mode Fixture CMRR


SimSmith Balun RUSE Block



FT140-43 7T Type RG174

All Files: FR43.zip


VNWA Common Mode Fixture CMRR


SimSmith Balun Model and VNWA Common Mode Fixture CMRR



FT140-43 7T CMR Using SSA3021X

Fixture with 10dB Attenuator


Fixture Schematic



SSA Example with 10dB Attenuator



SimSmith Model, VNWA, SSA 0dB, and SSA 10dB





Previous measurements using 2 port with 1:10 Transformer CMRR Fixture


VNWA Common Mode Fixture CMRR