Part 3 Flashcards
The distributed analysis of uniform transmission lines was started by ________
William Thomson (Lord Kelvin) in 1855
The distributed analysis of uniform transmission lines was completed by
Oliver Heaviside about 1885
refer to the reduction of power or signal strength as electricity or
data travels through a transmission line
Transmission Losses
Types of Transmission Losses
Copper Losses
Dielectric Losses
Radiation and Induction Losses
Evanescent Wave Losses
Four Wave Mixing
most common type of loss, these occur due to the resistance of the conductor material, leading to power dissipation in the form of heat.
Copper Losses
proportional to the square of the current (I²R) and are exacerbated by
the skin effect
Copper Losses
At high frequencies, the current tends to concentrate near the surface of
the conductor. This reduces the effective cross-sectional area for current
flow, increasing resistance and leading to power loss
Skin Effect
occur when the insulating material between conductors absorbs
energy from the alternating electric field, converting it into heat.
depend on the material’s dielectric constant and frequency
Dielectric Losses
In a coaxial cable, the dielectric material between the inner and outer conductors
can experience dielectric losses, leading to
signal attenuation
In microwave transmission, high-frequency signals passing through dielectric
substrates _______
suffer from dielectric heating.
The magnitude of dielectric loss is determined by the dielectric’s permittivity and
dielectric loss tangent.
The magnitude of dielectric loss is determined by the
dielectric’s permittivity and dielectric loss tangent.
Dielectric Loss Formula
ω x ϵ0 x ϵr x tanδ E²
Where:
Ploss = Power loss per unit volume (W/m³)
ω = 2πf = Angular frequency
ϵ0 = Permittivity of free space
ϵr = Relative permittivity
tanδ = Dielectric loss tangent
E = Electric field strength
At high frequencies, the transmission line can act as an antenna,
radiating some of the electromagnetic energy into space. This is particularly
significant for open-wire transmission lines
Radiation Losses
If the transmission line is located near metallic objects, currents can be
induced in these objects, leading to power loss.
Induction Losses
non-propagating waves that exist in certain media where the
signal frequency is lower than the cutoff frequency.
Evanescent Wave Losses
In optical fibers, If the signal frequency is lower than the cutoff frequency of
this dominant mode, the signal will propagate as an evanescent wave, which
decays rapidly along the fiber.
Signal Frequency below Dominant Mode
In fiber optic systems, this can occur when the harmonics of two signal wavelengths _________________ of a third
wavelength. This can lead to the generation of new frequencies and distortion of
the original signals.
Four-Wave Mixing;
overlap with the frequency (blank)
In long-haul fiber optic systems, four-wave mixing can be a significant source of _____________, especially at high data rates.
noise and distortion
formula for four wave mixing wavelength
FWM = 2/(1/λ1 + 1/λ2 - 1/λ3)
