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What is the center of a Smith chart?
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What is a Smith chart?
Why do inductive impedances appear in the upper half of the Smith chart?
Mar 13, 2020 · ANSWER: The resistance axis. The arcs on a Smith chart represent points with constant reactance, and the large outer circle on which the reactance arcs terminate is called the reactance axis. Points on the reactance axis have a resistance of 0 ohms.
- Example 1: Adding A Series Capacitor
- Example 2: Sweeping The Value of A Series Capacitor
- Example 3: Adding A Series Inductor
- Example 4: A Series RC Network Frequency Sweep
- Example 5: A Series Rl Network Frequency Sweep
- Example 6: A Series RLC Network Frequency Sweep
With a normalized load impedance of z1 = 0.5 + j, the reflection coefficient is Γ1 = 0.62 ∠∠ 82.87° (Equation 1). If we add to this impedance a 10 pF series capacitor (C1 = 10 pF), what would be the new impedance and reflection coefficient? Assume that the operating frequency is 211.7 MHz and the reference impedance is Z0 = 50 Ω. The load impedance...
If we add a series capacitor Cs to a normalized load impedance of z1 = 0.5 + j and sweep the capacitor value from +∞ to 5 pF, what would be the overall impedance contour on the Smith chart? We can use the results of the previous example to answer this one. To this end, we replace the circuit schematics of Figure 3 with their equivalent circuits, as...
The addition of a series inductor makes the reactive component of the impedance more positive. In this case, we follow the constant-resistance circle in a clockwise direction to find the new impedance. For example, assume that the operating frequency is 211.7 MHz and Z0 = 50 Ω. If we add a 37.58 nH series inductor to z1 = 0.5 + j, the normalized re...
Let’s see how the impedance of a series RC circuit changes with frequency. Assume that R = 25 Ω, C = 10 pF, and Z0 = 50 Ω. The impedance of a series RC circuit is: Z=R+1jωC=R−1ωCjZ=R+1jωC=R−1ωCj The real part of the normalized impedance works out to r = 0.5. Therefore, the impedance of this circuit is on the constant-resistance circle of r = 0.5. T...
What would be the impedance contour of a series RL circuit with R = 50 Ω and L = 30 nH if we sweep the frequency from DC to infinity? With Z0 = 50 Ω, the impedance of this RL network is on the constant-resistance circle of r = 1. The reactive component of the normalized impedance is x=LωZ0x=LωZ0, which is always positive. As the frequency is swept ...
What would be the impedance contour of a series RLC circuit with R = 10 Ω and L = 20 nH, and C = 2 pF if we sweep the frequency from DC to infinity? With Z0 = 50 Ω, the impedance of this series RLC network is on the constant-resistance circle of r = 0.2. At the resonant frequency fr, the reactance of the inductor cancels that of the capacitor, leav...
Jul 23, 2015 · In terms of reactances, lines above the real axis in the chart (the positive arcs from the second derived equation) represent inductive reactances, while those below (negative arcs) represent capacitive reactances.
You can find books and articles describing how a Smith chart is a graphical representation of the transmission line equations and the mathematical reasons for the circles and arcs, but these things don't really matter when you need to get the job done.
The point at which all the circles touch is for impedance z = ∞ (an open circuit); the opposite left-hand point is for z = 0 Ω (an open circuit). For the reactive (imaginary) part of the impedance, the chart uses arcs that originate on the right-hand side; all points on a given arc have the same reactance value.
Sep 13, 2019 · Impedance Smith Chart contains two major elements which are the two circles/arcs which define the shape and data represented by the Smith Chart. These circles are known as;
Jul 29, 2021 · Figure 3: The Smith chart shows arcs of constant resistance (a) and circles of constant reactance (b) which are merged and overlaid (c) to provide a perspective across all impedance possibilities. (Image source: ARRL.org)
