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page 79

7.1.3 a-Parameters (transmission)

7.1.4 b-Parameters (transmission)

7.1.5 h-Parameters (hybrid)

7.1.6 g- Parameters (hybrid)

7.2 PROPERTIES

If one set of parameters is known, other parameters can be found using simple conversions. This can help when one set of parameters is needed, but cannot be measured directly.

Simple cases of networks are reciprocal and symetrical. When a network is neither of these, then it typically has active components, dependant sources, etc.

7.2.1 Reciprocal Networks

If a voltage is applied at one port, the short circuit current out the other port will be the same, regardless of which side the voltage is applied to.

Reciprocal networks are only possible when passive elements are used.

The parameters that indicate a reciprocal networks are,

page 80

z12

= z21

 

y12

= y21

 

 

 

 

 

 

 

det

a11

a12

= 1

 

a21

a22

 

 

 

 

 

 

 

det

b11

b12

= 1

 

b21

b22

 

 

 

 

 

 

h12

= –h21

 

g12 = g21

With any reciprocal network we only need to find 3 of the four parameters, the last can be determined mathematically.

7.2.2 Symmetrical Networks

This is a special case of the reciprocal network where the input and output parameters are identical.

In addition to the reciprocal constraints, we must also consider,

z11 = z22

y11 = y22

a11 = a22

b11 = b22

 

 

 

 

 

 

det

h11

h12

=

1

 

h21

h22

 

 

 

 

 

 

 

 

det

g11

g12

=

1

 

g21

g22