SMITH CHART Flashcards
is one of the most
useful graphical tools for high
frequency circuit applications. The
chart provides a clever way to
visualize complex functions and it
continues to endure popularity
decades after its original conception.
Smith Chart
is simply a presentation of all possible complex impedances with respect to coordinates defined by the reflection coefficient or it can be defined mathematically as one port scattering parameter
Smith Chart
It’s a circular plot with a lot of interlaced
circles on it; when used correctly, matching
impedances with apparent complicated
structures can be made without any
computations. The only effort required is the reading and following of values along the circles.
Smith Chart
Who invented the Smith Chart?
Phillip Hagar Smith
was an electrical engineer,
who became famous for his invention of the Smith chart.
Phillip Hagar Smith
Where and when did Smith graduated?
Tufts College in 1928
While working for ______, Smith invented his
eponymous Smith chart
RCA (RADIO CORPORATION OF AMERICA)
When did Smith retired from Bell
Labs
1970
Smith Chart was primarily developed, extended, and refined by Phillip Hagar Smith, in a series of published works between _____ and _______
1939 and 1969
is a wave that remains stationary, formed by the interference of two waves traveling in opposite directions
STANDING WAVE
Points of zero amplitude
Nodes
Points of maximum amplitude
Antinodes
is the ratio of reflected power to incident power in a waveguide and is equal to the square of the voltage reflection coefficient but without phase. In a lossless waveguide, it remains constant, while in an attenuating
waveguide, it decreases toward the generator
Power reflection coefficient
Power reflection coefficient when expressed in dB, it is known as
return loss
As voltage and current waves travel toward the load in a waveguide, some power is
lost due to conductor resistance and dielectric leakage. This power loss, known as ______________, occurs continuously along the waveguide
attenuation or one-way transmission loss
When the input impedance Zin, is equal to the characteristic impedance Zc and the load impedance ZL. There are no standing
waves and changing the frequency of the generator will not change the input impedance of the line. In this case, there is a maximum possible power transmitted to the load, and the line is said to be
flat or nonresonant
If impedance of load ZL is not equal to the characteristic impedance, the line may appear
parallel or resonant circuit
represents inductive reactance. As you move upwards on the chart, the imaginary part of the impedance increases in the positive direction, which corresponds to inductive behavior
upper half of the Smith chart
represents capacitive reactance. As you move downwards, the imaginary
part of the impedance becomes negative, which corresponds to capacitive behavior.
lower half of the Smith chart
is marked “WAVELENGTHS TOWARD GENERATOR” (that is, from the load).
The values on this scale increase when moving around the circle in a clockwise (CW) direction.
outer scale
is marked “WAVELENGTHS TOWARD LOAD” (that is, from the generator). The
values on this scale increase when moving around the circle in a counterclockwise (CCW) direction
inner scale
shows how much the reflected wave is phaseshifted when bouncing back
reflection coefficient angle
shows how much the signal’s phase changes as it continues through the system
transmission coefficient angle (θΓ)
is at the center, where there is no reflection (Γ=0) ensuring maximum power transfer with no signal loss
matched load (ZL=Zo)
