zmicro.m

使用矩量法计算微带天线的特征阻抗

% characteristic impedance of a microstrip line
 clear
 er=4.8; d=1/16;
% find w/d for given Zo
 Zref=110; Zo=Zref;
 A=Zo/60*sqrt((er+1)/2)+(er-1)/(er+1)*(.23+.11/er);
 B=377*pi/2/Zo/sqrt(er);
 ratio1=8*exp(A)/(exp(2*A)-2);
 ratio2=2/pi*(B-1-log(2*B-1)+(er-1)/2/er*(log(B-1)+.39-.61/er));
 if ratio1 < 2, ratio=ratio1; end
 if ratio2 >= 2, ratio=ratio2; end
 ee=(er+1)/2+(er-1)/2/sqrt(1+12/ratio);
% check the impedance using the reverse formulas
  if ratio <=1, Z0=60/sqrt(ee)*log(8/ratio+ratio/4); end
  if ratio >1, Z0=120*pi/sqrt(ee)/(ratio+1.393+.667*log(ratio+1.444)); end
 disp('-------------- 50 OHM LINE DIMENSIONS -----------------')
 disp(['design characteristic impedance (ohms): ',num2str(Zo)])
 disp(['relative permittivity: ',num2str(er)])
 disp(['substrate thickness, (in): ',num2str(d),', (m): ',num2str(d*.0254)])
 disp(['effective relative permittivity: ',num2str(ee)])
 disp(['ratio W/d: ',num2str(ratio)])
 disp(['line width, W (in): ',num2str(ratio*d),', (m): ',num2str(ratio*d*.0254)])
 disp(['computed characteristic impedance (ohms): ',num2str(Z0)])
% antenna dimensions
 f=8.5e9; wavl=3e8/f/sqrt(ee);
 L=wavl/2;
 disp('----------------- PATCH DIMENSIONS --------------------')
 disp(['frequency, f (GHz): ',num2str(f/1e9)])
 disp(['patch length, L (m): ',num2str(L)])
 disp(['patch length, L (in): ',num2str(L/.0254)])

% equal Y power splitter -- recompute new dimensions
 Zo=Zref*2;
 A=Zo/60*sqrt((er+1)/2)+(er-1)/(er+1)*(.23+.11/er);
 B=377*pi/2/Zo/sqrt(er);
 ratio1=8*exp(A)/(exp(2*A)-2);
 ratio2=2/pi*(B-1-log(2*B-1)+(er-1)/2/er*(log(B-1)+.39-.61/er));
 if ratio1 < 2, ratio=ratio1; end
 if ratio2 >= 2, ratio=ratio2; end
 ee=(er+1)/2+(er-1)/2/sqrt(1+12/ratio);
% check the impedance using the reverse formulas
  if ratio <=1, Z0=60/sqrt(ee)*log(8/ratio+ratio/4); end
  if ratio >1, Z0=120*pi/sqrt(ee)/(ratio+1.393+.667*log(ratio+1.444)); end
 disp('------------ POWER SPLITTER DIMENSIONS ----------------')
 disp(['design characteristic impedance (ohms): ',num2str(Zo)])
 disp(['relative permittivity: ',num2str(er)])
 disp(['effective relative permittivity: ',num2str(ee)])
 disp(['substrate thickness, (in): ',num2str(d),', (m): ',num2str(d*.0254)])
 disp(['ratio W/d: ',num2str(ratio)])
 disp(['line width, W (in): ',num2str(ratio*d),', (m): ',num2str(ratio*d*.0254)])
 disp(['computed characteristic impedance (ohms): ',num2str(Z0)])