EE Pro for TI 89, 92 Plus
Analysis - Transmission Lines
44
ββ
:
(Phase Constant in degrees or radians/unit length)
Returns a real number, or algebraic expression.
λλ
:
(Wavelength in unit length)
Returns a real number or algebraic expression.
vp
:
(Phase Velocity in unit length/s)
Returns a real number or algebraic expression.
Zoc_
: (Open Circuit Impedance in
Ω
)
Returns a real or complex number, or
algebraic expression.
Zsc_
: (Short Circuit Impedance in
Ω
)
Returns a real or complex number, or
algebraic expression.
ρρ__
:
(Reflection Coefficient)
Returns a real or complex number, or
algebraic expression.
SWR
: (Standing Wave Ratio)
Returns a real number, or algebraic expression.
Example 11.1
A transmission line has a series inductance of 1 mH/mile, a line resistance of 85.8 ohm/mile, a conductance of .0015
x 10-6 Siemens/mile, and a shunt capacitance of 62 x 10-9 F/mile. For a load impedance of 75 ohms and a
frequency of 2000 Hz, compute the line characteristics 3 miles away from the load.
Note: Since the unit length is the mile, all entered and calculated values are with respect to miles.
Input Screen
Output Screen (upper half)
Output Screen (lower half)
1. Enter the values 0.001, 85.8, and .0015E-6 for
L
,
R
, and
G
, respectively.
2. Enter the values 62E-9, 75, and 3 for
C
,
ZL_
, and
d
, respectively.
3. Enter 2000 for
f
.
4. Press
„
to calculate the results. The input and output screen displays are shown above.
11.2 Line Parameters
This topic computes fundamental parameters of a transmission line from measured data. The algorithm used in this
section solves for
γ
in the equation 11.2.1, where
γ
=
α
+ j
β
. In general
γ
, Zsc_, and Zoc_ have complex values. In
solving for
γ
, there is a principal value and a set of equivalent values because of the cyclical nature of the equation.
Recognizing the fact that physical parameters such as R, L, G, C, and vp are all real and positive numbers, extreme
caution should be exercised when entering input data. In particular,
d
should be less than one wavelength.
tan(
)
_
_
γ ⋅ =
d
Zsc
Zoc
Eq.
11.2.1
Field Descriptions - Input Screen
Zoc_
: (Open Circuit Impedance in
Ω
)
Enter a real or complex number, variable or algebraic
expression of defined terms.
Zsc_
:
(Short Circuit Impedance in
Ω
)
Enter a real or complex number, variable or algebraic
expression of defined terms.