用matlab编写的电磁学方面的函数和图像

				% qwt2.m - quarter wavelength transformer with 1/8-wavelength shunt stub
				%                           
				% ---------------==========----|--|
				% main line Z0       Z1        |  ZL
				% ---------------==========-|--|--|
				%                  L1=1/4   |  |
				%                           |Z2| L2=1/8 or 3/8                
				%                           |__| shorted or opened
				%
				% Usage: [Z1,Z2] = qwt2(ZL,Z0)
				%
				% Z0   = impedance of main line
				% ZL   = complex load impedance
				%
				% Z1 = impedance of 1/4-wavelength segment
				% Z2 = impedance of stub (sign of Z2 determines 1/8, 3/8, shorted, opened)
				%
				% notes: Stub susceptance cancels load susceptance
				%
				%        For a short-circuited 1/8-stub, we have:
				%        Y = YL+Ystub = (GL+jBL)+(-jY2)
				%        Y2 = BL, Z2=1/BL, and Z1 = sqrt(Z0/Y) = sqrt(Z0/GL)
				%
				%        Z2 > 0, use 1/8 shorted, or, 3/8 opened (Ystub = -jY2)
				%        Z2 < 0, use 3/8 shorted, or, 1/8 opened (Ystub =  jY2)
				%
				%        for a balanced stub use impedance 2*Z2 for each stub leg
				
				% S. J. Orfanidis - 2000 - www.ece.rutgers.edu/~orfanidi/ewa
				
				function [Z1,Z2] = qwt2(ZL,Z0)
				
				if nargin==0, help qwt2; return; end
				
				GL = real(1/ZL);
				BL = imag(1/ZL);
				
				Z1 = sqrt(Z0/GL);
				Z2 = 1/BL;