RE: NEC-LIST: Infinite periodic structure

Hello Alexandre

Regarding your question about using railway overhead power line for
communications, it sound the same matter as power line carrier, used
by utilities to communicate through power lines. The carrier
frequencies used in such cases ranges from 20 to 500 kHz, and there
are as many propagation modes as parallel lines. Your concern about
parallel lines is not so troublesome. In fact, the additional lines
usually help to the transmission (except in very short lines, where
mode mixes and it can bring to a situation where there is not
communication at all).

Carson stated the fundamentals of transmission over multiple wires,
many years ago, and today it is managed using matrix mathematical
tools, used easily (To those who know how!) inside ATP software
(Alternative Transient Program).

To calculate line parameters in these cases, the best program is ATP,
public domain simulation software, as popular among electrical
engineers as NEC among communication and antenna engineers.

As usual, an infinite transmission line can be modelled as a finite
segment with ending impedance equal to line characteristic impedance.
The problem is that the characteristic impedance change with
frequency.

Juan M. Trillos

-----Mensaje original-----
De: Alexandre Kampouris
Enviado el: domingo 12 de noviembre de 2000 15:48
Para: nec-list_at_ee.ubc.ca
Asunto: NEC-LIST: Infinite periodic structure

'day,

I'd like to model railway overhead power lines used as a transmission
line, in order to determine their usability for data transmission from
a locomotive through the pantograph....
Received on Wed Nov 15 2000 - 02:51:57 EST