How to model Klopfenstein Taper in CST MWS?

Hi,

I am simulating some antennas on CST MWS.
Does anyone know how to model a Klopfenstein Taper ? Is there any existing program on how to calculate or generate the coordinates ?

Thanks in advance

Regards,
abti

Hi abti,
you must draw it in AutoCAD and save as *.dxf and load in CST.
for drawing in AutoCAD you can use AutoLISP to draw any function y=f(x). I attached a AutoLISP routine for this porpose.Please folow me:
1. find my AutoLISp file.
3. edit it by filling "x" and "y" with correct value that you want to draw.
2. open AutoCAD and Operate : Tools\AutoLISP\Load menu and load this routine.
3. After Successfully loading, type "balun" in command line of AutoCAD.
4. your y = f(x) curve is plotted. save it and load in CST or HFSS or others simulators.

KMPA

I've question relating to length of Klopfenstein taper.

I designing impedance transformer at 1-5 GHz band. How depends length of transformer on the bandwidth?

For example by using Tchebyshev λ/4 transformer, I can simply calculate number of section for securing needed bandwith.

Thanks fo help and apologize me for my English

i am having matlab code for this tapper....

Dear theepak

Could you send me your code. Thank you

Hallo theepak,
the minimum operating frequency decreases with increasing length.
fmin and waveguide loss are the tradeoffs.
elektr0

This code i got from matlab website....


function Zlist=bklop(Zo,Zload,N,RdB)
% Calculate impedance list for a Klopfenstein taper
% of unit length.
%
% Zlist=bklop(Zo,Zload,N,RdB)
%
% Zo......Characteristic impedance (Ohms)
% Zload...Load impedance to match to (Ohms)
% N.......Number of sections used to approximate taper (integer)
% RdB.....Operating band ripple (dB)
%
% e.g. Zlist=bklop(50,100,60,-25) % Match a 100ohm load to a 50ohm line
% % with operating band ripple at -25dB.
% % Taper defined as list of 60 sections
%
% Note : Only valid for Zload>Zo
%
% Matches a load impedance Zload to a standard line impedance Zo
% using Klopfenstein taper.
% Taper profile is returned as a list of impedances, the optimum length
% for this design of taper is 0.565 lambda.
%
% Impedance Values
% Zo ---> [ Z1 ] [ Z2 ] .... [ ZN ] <-- Zload
%
% Ref D.M Pozar Microwave Engineering 2nd Ed Page 291

% N.Tucker ActiveFrance 2010




Tld=log(Zload/Zo)*0.5; % Reflection coefficient of load
Trip=10.^(RdB/20); % Lin value of ripple in operating band


A=acosh(Tld/Trip); % Intermediate variable in calculation


z=0; % Fractional distance along taper
dz=1/(N-1); % Incremental distance


Zx=zeros(1,N);
for c=1:N % Loop for impedance values along taper

M=round(z*100+25); % Number of steps for the numerical integration
PsiXA=0;
y=0;
dy=((2*z-1)/(M-2)); % Increment for numerical integration

for d=1:M % Loop for PsiXA numerical integration
PsiXA=PsiXA+besseli(1,A*sqrt(1-y.^2))/(A*sqrt(1-y.^2))*dy;
y=y+dy;
end

% Calculate impedance as a function of distance along the
% unit length transformer
LNZx=0.5*log(Zo*Zload)+(Tld/cosh(A))*(A.^2)*real(PsiXA);
Zx(1,c)=exp(LNZx);
z=z+dz;
end


Zlist=[Zo,Zx,Zload]; % Assemble the list of impedances for output
X=1:1:N; % X-axis vector for plotting

figure(10);
plot(X,(Zx),'b-',X,(Zx),'+');
xlabel('Zo Matching Section Number Zload');
ylabel('Impedance (Ohms)');
title('Transformer Impedances')
grid on;

chartname=sprintf(' Transformer Impedances ');
set(10,'name',chartname);