## Transmission Line (TL)

```Purpose: To generate a transmission line between any two points on the
structure.  Characteristic impedance, length, and shunt admittance
are the defining parameters.
Card:

Cols	Parameter
----------------------
1- 2        TL
3- 5        I1
6-10        I2
11-15        I3
16-20        I4
21-30        F1
31-40        F2
41-50        F3
51-60        F4
61-70        F5
71-80        F6

Parameters:
Integers I1-I4 - (the integer specifications are identical to those
on the network (NT) card.)

Floating Point
(F1) - The characteristic impedance of the transmission line in
ohms.  A negative sign in front of the characteristic
impedance will act as a flag for generating the transmission
line with a 180 degree phase reversal (crossed line)
if this is desired.
(F2) - The length of transmission line in meters.  If this field
is left blank, the program will use the straight line dis-
tance between the specified connection points.

The remaining four floating-point fields are used to
specify the real and imaginary parts of the shunt admittances
at end one and two, respectively.

(F3) - Real part of the shunt admittance in mhos at end one.
(F4) - Imaginary part of the shunt admittance in mhos at end one.
(F5) - Real part of the shunt admittance in mhos at end two
(F6) - Imaginary part of the shunt admittance in mhos at end two.
```
Notes:
• The rules for transmission line cards are the same as for network cards. All transmission line cards for a particular transmission line configuration must occur together with no other cards (except NT cards) separating than. When the first TL or NT card is read following a card other than a TL or NT card, all previous network or transmission line data are destroyed. Hence, if a set of TL cards is to be modified, all transmission line and network data must be input again in the modified form. Dimensions in the program limit the number of cards in a group that may be specified. In the NEC demonstration deck, the number of two-port networks (specified by NT cards and TL cards) is limited to thirty, and the number of different segments having network ports connected to them is limited to thirty.
• One or more networks (including transmission lines) may be connected to any given segment. Multiple network ports connected to one segment are connected in parallel.
• If a transmission line is connected to a segment that has been impedance loaded (i.e., through the use of an LD card), the load acts in series with the line.
• Use of transmission line cards (TL) after any form of execute requires the recalculation of the current only, and does not require recalculation of the matrix.
• NT and TL cards do not affect symmetry.

This file was last modified on Monday,