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chebtr2

Chebyshev design of broadband reflectionless quarter-wave transformer

Calling Sequence

[n,a,b,A] = chebtr2(na,nb,M,DF)

Parameters

na,nb

refractive indices of left and right media

M

number of quarter-wave sections

DF

fractional bandwidth about center frequency f0, DF = Df/f0

n

designed refractive indices = [na,n(1),n(2),...,n(M),nb]

a,b

order-M denominator and numerator polynomials of reflection response

A

dB attenuation of reflectionless band (relative to unmatched case)

Description

chebtr2(na,nb,M,DF) is used for Chebyshev design of broadband reflectionless quarter-wave transformer. implements the Collin/Riblet design of broadband quarter-wave transmission line transformers; stopband specs are in terms of the reflection response. similar to chebtr, except here M,DF are specified instead of A,DF, see also chebtr3 in which M,A are specified. the left and right bandedges are at F1 = 1 - DF/2, F2 = 1 + DF/2, the phase thickness of layers is = delta = (pi/2)*(f/f0) = (pi/2)*(la0/la), at f=f0, la=la0, the layers are quarter-wave, the reflection response is Gamma(z) = B(z)/A(z), z=exp(2*j*delta) = exp(j*pi*f/f0). the refractive indices satisfy: n(i)*n(M+1-i) = na*nb, i=1,2,...,M. for transmission lines, replace n = [na,n(1),n(2),...,n(M),nb] by the characteristic admittances Y = [Ya,Y(1),Y(2),...,Y(M),Yb], that is, [Y,a,b,A] = chebtr2(Ya,Yb,M,DF), with Ya=line, Yb=load (Ya,Yb must be real)

Examples

add sample pgm

See Also

Author

Used Functions

This function uses the functions bkwrec and poly2.

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