i need help in obtaining graphs for decoupling technique for antennas

Charity Kasubi

New Member
Aug 15, 2011
1
1
I am doing a project titled decoupling technique for antennas and high isolation my code is in matlab software i cant get correct graphs for isolation and return loss of antenna(below -10dB before and after decoupling technique) .This is an IEEE conference paper.Below is the coding i have done:
%%%%%%%%%%%%%%%%%%%%% A Decoupling Technique for Increasing the Port Isolation Between Two Strongly Coupled Antennas %%

%%------------------- Define Variables:----------------------%%
% N - # of elements in array %
% d - element spacing in wavelengths %
% ang - theta in deg %
% thetaS - desired user AOA (deg) %
% thetaI - interferer AOA (deg) %
% T - period of desired signal %
% t - time axis for desired signal %
% S - desired signal %
% I - interfering signal %
% vS,vI - steering vectors of desired user and interferers %
% X - total array factor %
% Rxx - total received signal correlation matrix %
% mu - convergence parameter %
% w - weights of ULA determined using LMS algorithm %
% x - total received signal %
% y - array output %
% e - error between array output and desired signal %
% theta - range of AOA's (rad) %
% AF - weighted array output
% S11,S12,S21 and S22 - scattering matrix parameters %
% ZG and ZL - load impedances
% Gin and Gout - input & output reflection coefficients
%%-----------------------------------------------------------%%
%----- -----%
clc;clear
all, close all;
d = .5;
% element spacing in terms of wavelength d = lambda/2
gamma = 0.5;
%S11 = 0.61<165* , S21 = 3.72<59* , S12 = 0.05<42* , S22 = 0.45<-48*;
Sm = smat([0.61 165 3.72 59 0.05 42 0.45 -48]);
% -- Scattering matrix
Z0 = 50;
ZG = 10+20j; gG = z2g(ZG,Z0);
ZL = 30-40j; gL = z2g(ZL,Z0);


M = 2;
%input(' How many element do you want in uniform linear array? '); % number of elements in array
thetaS = 0;
%input(' Enter the desired users angle (in degrees)? ');
thetaI= 30;
%input ('Enter The Angle of Incidence of the Undesired Interference Source Signal : ') ; %30


%----- Assuming the Desired Signal & Interference signal -----%

it=1:200;
% number of iteration
T=3*10^8;
%T - period of desired signal
t=(it)*T/200;
S=sin(2*pi*t/T);
thetaS = thetaS*pi/180;
% desired user AOA
I = randn(1,200);
thetaI = thetaI*pi/180;
% interferer AOA

%----- Create Array Factors for each user's signal for linear array -----%

vS = []; vI = [];
i=1:M;
vS=exp(1j*(i-1)*2*pi*d*sin(thetaS)).';
% desired signal recieved STEERING VECTOR
vI=exp(1j*(i-1)*2*pi*d*cos(thetaI)).';
%intereference signal recieved
Gin = gin(Sm,gL);
Gout = gout(Sm,gG);
Gmag = sgain(Sm);
% GMAG = 41.50, or, 16.18 dB

figure(7)
plot([Gin,Gout],
'r--'),
xlabel(
'input reflection coeff')
ylabel(
'output reflection coeff')
title(
'Input & output reflection coefficient'),

%----- Solve for Weights -----%
w = zeros(M,1);
for
snr = 10; % signal to noise ratio

X=(vS+vI);

Rx=(X*X');
% correlation matrix..
end

mu=1/(2*real(trace(Rx)))
%mu = input('What is step size?')

% trace(Rx) is the maximum eigen value of correlation matrix of i/p signal

wi=zeros(M,max(it));
for
n = 1:length(S) % selecting the training inputs
x = S(n)*vS + I(n)*vI;
y=w'*x;
%y = w*x. calulating the "------- OUTPUT BEAMFORMER-----.. where w is weight and x is the input signal'
e = conj(S(n)) - y ;
% calulating the --- ERROR ---- i.e " e = reference signal(desired) - output signal
esave(n) = abs(e).^2;
% learning curve
w=w+mu*conj(e)*x;
% w = w +mu*e*conj(x) calculating the ------WEIGHT----
wi:),n)=w;
% store weight for matrix to plot
yy(n)=y;
end
w = (w./w(1));
% normalize results to first weight % Array operations "." Element-by-element multiplicative operations are obtainedFor example,

% C = A ./ B is the matrix with elements c(i,j) = a(i,j)/b(i,j).

%----- Plot Results -----%

theta = -pi/2:.02:pi/2;
AF = zeros(1,length(theta));

% Determine the array factor for linear array

for
i = 1:M
AF = AF + w(i)'.*exp(1j*(i-1)*2*pi*d*sin(theta));
end

% two closely spaced printed monopole antennas %
figure(1)
AF = abs(AF);
polar(theta,AF,
'-r'), title('Measured radiation patterns of the two closely spaced printed monopole antennas'),
grid
on;
xlabel(
'Angle(Degree)')
ylabel(
' Normalized gain(ratio) ')

%**************************************************************************


figure(2);
plot(it,S,
'k',it,yy,'r--')
xlabel(
'No. of Iterations')
ylabel(
'Signals')
legend(
'Desired signal','Array output')

%*********MY ESTIMATE*************************************************************
figure(3);semilogy(it,esave,
'k')
xlabel(
'Iteration no.')
ylabel(
'error')

figure(4);plot(it,wi)
xlabel(
'Iteration no.')
ylabel(
'|weights|')
w=0:pi/20:pi;
q=1:1:7;
figure(5),

for
i=0:pi/20:pi
brf_rect((i)*(20/pi)+1)=0.318+2*(0.022*cos(i)+0.265*cos(2*i)+0.045*cos(3*i));
end
plot(w,brf_rect,
'r-');hold on % rectangular window
plot(w,1.2*brf_rect,
'k--');
xlabel(
'Frequency (Hz)')
ylabel(
'Return Loss(dB)')
title(
'The Return Loss of the monopole')

figure(6),
for
i=0:pi/20:pi
brf_hanning((i)*(20/pi)+1)=0.318+2*(0.0165*cos(i)+0.066*cos(2*i));
end
plot(w,brf_hanning,
'g-') ;hold on % Hanning window
plot(w,1.2*brf_hanning,
'k--') ;
xlabel(
'Frequency (Hz)')
ylabel(
'Isolation(dB)')
title(
'The Isolation of the monopole')

 
Rest easy dada Kasubi naona shule yako ulikuwa unapiga vitu vigumu tu.

Pumzika kwa amani mtaalam
 
Kwa kweli.. Halafu maskini hakupata jibu toka JF..! May be kama alifuatwa PM
Humu wapo wataalamu kuanzia kwenye Dish kuja kwenye Tv, Ving'amuzi, Radio etc na pia kwenye simu aka wazee wa software wapo kibao. Hiyo nadhani ilikuwa juu ya uwezo
 
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