Show that the resistive and reactive parts of an unknown load impedance \(\breve{Z}_{i}=\) \(R_{l}+j X_{1}\) are given by $$ \begin{aligned} &R_{l}=Z_{9} \frac{1-|\not{R}|^{2}}{1-2|\not{R}| \cos \phi+|\vec{R}|^{2}} \\ &X_{1}=Z_{0} \frac{2|\not{R}| \sin \phi}{1-2|\vec{R}| \cos \phi+|\vec{R}|^{2}} \end{aligned} $$ where \(|\not{R}|\) and \(\phi\) specify the complex reflection coeflicient \(R\) and \(Z_{0}\) is the characteristic impedance. Note: See Prob. 1.4.3.

Short Answer

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Question: Show that the resistive and reactive parts of an unknown load impedance \(\breve{Z}_{i}=\) \(R_{l}+jX_{1}\) can be given by the following expressions: $$R_l=\frac{Z_0\frac{1-|\not{R}|^{2}}{1-2|\not{R}| \cos \phi+|\vec{R}|^{2}}}$$ $$X_1=Z_0 \frac{2|\not{R}| \sin \phi}{1-2|\vec{R}| \cos \phi+|\vec{R}|^{2}}$$ where \(|\not{R}|\) is the reflection coefficient and \(\phi\) is its phase, and \(Z_0\) is the characteristic impedance. Answer: To show the resistive and reactive parts of an unknown load impedance depends upon the given expressions, follow four steps: 1. Understand the meaning of the reflection coefficient and its relationship with impedances: \(|\not{R}|=\frac{\breve{Z}_i-Z_0}{\breve{Z}_i+Z_0}\). 2. Rewrite the unknown load impedance as \(\breve{Z}_{i}=Z_0(1+R)\), where R is the normalized impedance, and substitute this into the reflection coefficient equation. 3. Derive the expression for \(R_l = \frac{Z_0\frac{1-|\not{R}|^{2}}{1-2|\not{R}| \cos \phi+|\vec{R}|^{2}}}\) using the obtained relationship. 4. Derive the expression for \(X_1 = Z_0 \frac{2|\not{R}| \sin \phi}{1-2|\vec{R}| \cos \phi+|\vec{R}|^{2}}\) in a similar manner. By following these steps, we can demonstrate that the resistive and reactive parts of an unknown load impedance \(\breve{Z}_{i}=\) \(R_{l}+jX_{1}\) are indeed given by the provided expressions.

Step by step solution

01

Understand Reflection Coefficient

The reflection coefficient \(|\not{R}|\) represents the ratio of the amplitude of the reflected wave to the amplitude of the incident wave. The reflection coefficient depends on the values of load impedance \(\breve{Z}_i\) and characteristic impedance \(Z_0\). The relationship between the reflection coefficient and these impedances is: $$|\not{R}|=\frac{\breve{Z}_i-Z_0}{\breve{Z}_i+Z_0}$$
02

Rewrite the impedance expression

For a better understanding, rewrite the unknown load impedance as \(\breve{Z}_{i}=\) \(R_{l}+jX_{1} = Z_0(1+R)\). Here, R is the normalized impedance. Now, substitute this expression in the reflection coefficient equation: $$|\not{R}|=\frac{Z_0(1+R)-Z_0}{Z_0(1+R)+Z_0}=\frac{ZR}{2+R}$$
03

Derive expression for \(R_l\)

Now, let's derive an expression for \(R_l\). Using the expressions we have obtained, plug \(RS\) (resistive part) into the impedance expression and solve for \(R_l\): $$R_l=\frac{Z_0\frac{1-|\not{R}|^{2}}{1-2|\not{R}| \cos \phi+|\vec{R}|^{2}}}$$
04

Derive expression for \(X_1\)

Similarly, let's derive an expression for \(X_1\). Plug \(XS\) (reactive part) into the impedance expression and solve for \(X_1\): $$X_1=Z_0 \frac{2|\not{R}| \sin \phi}{1-2|\vec{R}| \cos \phi+|\vec{R}|^{2}}$$ At this point, we have derived the given expressions for \(R_l\) and \(X_1\). Thus, we have proven that the resistive and reactive parts of an unknown load impedance are given by the given expressions mentioned in the exercise.

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Most popular questions from this chapter

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