Isolation Transformer (Type N Balun)

T1100369-v1
July 8, 2011
Daniel Sigg

Theory of Operations

The design of the isolation transformer is shown in D1101077-v1. It implements a Mini-Circuits ADT1-1 transformer. The ground returns are connected through capacitors. Both connectors are isolated from the tubular case through capacitors as well.

Specifications

({{ ,    Minimum   ,    Nominal   ,    Maximum  }, {
Intrinsic delay ,  ,  
1.1 ns,  }, { ,  ,  ,  }, {Insertion loss (0.1MHz to 200 MHz), 0.2 dB,  , 3dB}, {Insertion loss (0.1MHz to 135 MHz), 0.2dB,  , 2 dB}, {Insertion loss (0.1MHz to 100 MHz), 0.2 dB,  , 1 dB}, {Insertion loss (0.1 MHz to 55 MHz), 0.2 dB,  , 0.5 dB}, { ,  ,  ,  }})

Setup

$TextStyle={FontFamily->"Helvetica",FontSize->13};

plotopt=PlotStyle->{{Thickness [0.007], RGBColor [1,0,0]},
			    {Thickness [0.007], RGBColor [0,0,1]},
			    {Thickness [0.007], RGBColor [0.1,0.7,0.2]},
			    {Thickness [0.007], RGBColor [0.5,0.5,0.2]}};

pathname="C:\\Users\\daniel\\Protel\\RF\\System\\Isolation\\docs\\";
filename1=pathname<>"RefMag.txt";
filename2=pathname<>"RefPhase.txt";
filename3=pathname<>"MeasMag.txt";
filename4=pathname<>"MeasPhase.txt";

Import Data

Reference

data1=Import[filename1,"Table"];
data2=Import[filename2,"Table"];
refdata=MapThread[{#1[[1]],(10^((#1[[2]])/20))(E^(I#2[[2]]°))}&,{data1,data2}];

Measured

data3=Import[filename3,"Table"];
data4=Import[filename4,"Table"];
measdata=MapThread[{#1[[1]],(10^((#1[[2]])/20))(E^(I#2[[2]]°))}&,{data3,data4}];

Process Data

Measured – Reference

data=MapThread[{#1[[1]],#1[[2]]/#2[[2]]}&,{measdata,refdata}];

Fixed Delay

((Phase[Last[data][[2]]])/(360 Last[data][[1]]))

Plot Results

Insertion Loss

ListLogLinearPlot[{((#[[1]])/(1*^6)),dB[#[[2]]]}&/@data,
Joined->True,
BaseStyle->$TextStyle,PlotStyle->{{Thickness [0.007], RGBColor [1,0,0]}},
PlotLabel->"Balun Insertion Loss",
FrameLabel->{"Frequency (MHz)","Insertion Loss (dB)"},
PlotRange->All,Frame->True,GridLines->Automatic]

Phase Delay

ListLogLinearPlot[{((#[[1]])/(1*^6)),Phase[#[[2]]]-((Phase[Last[data][[2]]])/(Last[data][[1]]))#[[1]]}&/@data,
Joined->True,
BaseStyle->$TextStyle,PlotStyle->{{Thickness [0.007], RGBColor [1,0,0]}},
PlotLabel->"Balun Phase Delay",
FrameLabel->{"Frequency (MHz)","Phase (°)"},
PlotRange->All,Frame->True,GridLines->Automatic]