pltdefaults

%%% 10lambda aperture with different d values
figure(1)
L=10;					% aperture

dlambdas=[.25 .5 1 2];
for ind=1:length(dlambdas);
  dlam=dlambdas(ind);
  M=L/dlam;				% number of elements

  c=sqrt(1/M)*ones(M,1);			% uniform weighting

  phivec=-90:.5:90;
  BP=beampattern(c,dlam,phivec);

  subplot(2,2,ind)
  plot(phivec,20*log10(abs(BP)));
  axis([-90 90 -40 0])
  xlabel('Angle (deg)')
  ylabel('Power (dB)')
  tstr=sprintf('d=%0.2f',dlam);
  title([tstr '\lambda'])
end

%%% d=0.5lambda with 4 different apertures
figure(2)
dlam=.5;
apertures=[2 4 8 16];

for ind=1:length(apertures)
  M=apertures(ind)/dlam;				% number of elements

  c=sqrt(1/M)*ones(M,1);			% uniform weighting
  
  phivec=-90:.5:90;
  BP=beampattern(c,dlam,phivec);

  subplot(2,2,ind)
  plot(phivec,20*log10(abs(BP)));
  axis([-90 90 -40 0])
  xlabel('Angle (deg)')
  ylabel('Power (dB)')
  tstr=sprintf('L=%0.0f',apertures(ind));
  title([tstr '\lambda'])
  
end

%%% Dolph-Chebychev tapered examples
figure(3)
dlam=.5;
L=10;
M=L/dlam;				% number of elements
c=ones(M,1);			% uniform weighting

cnotaper=1/sqrt(M)*c;
win=chebwin(M,50);
win=win/sqrt(win'*win);
ccheby50=win.*c;
win=chebwin(M,70);
win=win/sqrt(win'*win);
ccheby70=win.*c;

phivec=-90:.5:90;
BPnotaper=beampattern(cnotaper,dlam,phivec);
BPcheby50=beampattern(ccheby50,dlam,phivec);
BPcheby70=beampattern(ccheby70,dlam,phivec);

plot(phivec,20*log10(abs(BPnotaper)),'b-',...
    phivec,20*log10(abs(BPcheby50)),'r--',...
    phivec,20*log10(abs(BPcheby70)),'k-.');
axis([-90 90 -90 0])
xlabel('Angle (deg)')
ylabel('Power (dB)')
apstr=[sprintf('L=%0.0f',L) '\lambda'];
dlamstr=[sprintf('d=%0.2f',dlam) '\lambda'];
title([apstr '     ' dlamstr])
legend('No taper','Dolph-Chebychev -50','Dolph-Chebychev -70')

%%% Steered examples
figure(4)
dlam=.5;
L=10;
M=L/dlam;				% number of elements
phis0=0;
phis45=45;
phis90=90;

mvec=(0:M-1)';
uvec=dlam*sin(pi*phis0/180);
vphis0=1/sqrt(M)*exp(-j*2*pi*mvec*uvec);
c0=vphis0;

uvec=dlam*sin(pi*phis45/180);
vphis45=1/sqrt(M)*exp(-j*2*pi*mvec*uvec);
c45=vphis45;

uvec=dlam*sin(pi*phis90/180);
vphis90=1/sqrt(M)*exp(-j*2*pi*mvec*uvec);
c90=vphis90;

phivec=-90:.5:90;
BP0=beampattern(c0,dlam,phivec);
BP45=beampattern(c45,dlam,phivec);
BP90=beampattern(c90,dlam,phivec);

plot(phivec,20*log10(abs(BP0)),'b-',...
    phivec,20*log10(abs(BP45)),'r--',...
    phivec,20*log10(abs(BP90)),'k-.');
axis([-90 90 -40 0])
xlabel('Angle (deg)')
ylabel('Power (dB)')
apstr=[sprintf('L=%0.0f',L) '\lambda'];
dlamstr=[sprintf('d=%0.2f',dlam) '\lambda'];
title([apstr '     ' dlamstr])
legend('0 deg steering','45 deg steering','90 degree steering',2)