arsenal said:
and how to calculate the input impedance and the delay??
thanks a lot
'Gamma' is a complex attenuate and phase constant, knows at secondary transmissions line parameters:
gamma = alpha + jbeta
alpha = attenuate constant in Neper (1 neper = 8.686 dB) per length unit
beta = phase constant in radianer per length unit
gamma = alpha + jbeta = sqrt((r+jwl) * (g+jwc))
time delay = beta / 2PIf = beta/w in second per length unit
(if cable/transmissions line value is defined for 1 km and your wanted distans is 1 m: calculate timdelay = 0.001 * beta / 2PIf)
impedances:
Z=sqrt((r+jwl) / (g + jwc))
f = frequency in Hz
r = resistance in Ohm per length unit
g = conductance in Siemens per length unit
w = 2* PI*frequency in radianer per sec
l = inductance Henry per length unit
c = capacitance Farads per length unit
j = imaginay number j^2 = -1
and typical value for CAT-5 cable (Z=100 Ohm on 1 MHz) is:
c = 50 nF/km
r = 188 Ohm/km
l = 0.50 mH/km
g = 1E-7 S/km (frequency depend - incrase slowly on higher frequency depend of skin effect on copper and dielectric loss on insulator)
and 'c,r,l,g' knows as transmissions line primary parameters.
impedanses is more or less complex for frequency lower than 200 KHz for most of used telecom and data cables.
/Xxargs