PRACTICAL MATLAB® FOR ENGINEERS PRACTICAL MATLAB

280 Practical MATLAB® Applications for Engineers

ANALYTICAL Solution

For the circuit shown in Figure 3.59 (part a),

Z

Cj

jRCjLC

()

(/ )( )

() (/ )()(/ )












1

(^211)
For R = L = C = 1 ,
Z
j
jj
()
()
() ()





(^2)  1
For the circuit shown in Figure 3.60 (part b),
Z
Rj C j R LC
jLC
()
() (/)()(/ )
() (/ )







2
2
1
1
For R = 1000 Ω, L = 30 mH, and C = 0.47 μF (Figure 3.61),
Z
jj
j
()
()
.
()
.
()





1000 ^1 
047 10
1000
30 10 0 47 10
2
636
2

• 
  


• 
  


• 
  

  ---

  
  

   ^1
  30 10**^36 0 47 10.
  MATLAB Solution
  % Script file: circ Fig 359
  % R, L, and C in parallel
  % R = C = L = 1.
  echo on;
  w = 0:0.1:5;
  num = [0 0 1];
  den = [1 1 1];
  ZW = freqs (num, den, w);
  subplot(2, 1, 1);
  plot(w, abs(ZW));
  grid on;
  title(‘Magnitude and phase of Z(w)’);
  xlabel(‘w(rad/sec)’);
  ylabel(‘magnitude’);
  subplot(2, 1, 2);
  plot(w, angle(ZW)180/pi); % Figure 3.61
  xlabel(‘w(rad/sec)’);
  ylabel(‘phase in degrees’);
  grid on;
  C R
  Z L
  FIGURE 3.59
  Network with R = C = L = 1, over the range 0 ≤
  ω ≤ 5 rad/s of Example 3.9.
  C
  R
  Z L
  FIGURE 3.60
  Network with R = 1000 Ω, L = 30 mH, and C = 0.47 μF,
  over the range 7500 ≤ ω ≤ 9500 rad/s of Example 3.9.