Có 75+ tài liệu thuộc chủ đề "giáo trình giảng dạy"
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What is the radius R' of the light on the table?. However, TEM waves can also propagate in the region of finite volume between electrodes. Such electrode structures, known as transmission lines, are used for electromagnetic energy flow from power (60 Hz) to microwave frequencies, as delay lines due to the finite speed c of electromagnetic waves, and in pulse...
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so that the capacitance and inductance per unit length of this structure are. Thus far we have emphasized the field theory point of view from which we have derived relations for the voltage and current. However, we can also easily derive the transmission line equations using a distributed equivalent circuit derived from the following criteria:. Thus, we may discretize the...
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When RL = cO the reflection coefficient is unity so that V. When the incident and reflected waves overlap in space the voltages add to a stairstep pulse shape while the current is zero. For t 2 T, the voltage is Vo everywhere on the line while the current is zero.. When RL = 0 the load reflection coefficient is...
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Sinusoidal Time Variations 595. If the end at z = 0 were not matched, a new V+ would be generated. The voltage across the inductor is. Thus the total voltage and current for all time at z = I is given by (48) and (49) and is sketched in Figure 8-14c.. 8-3 SINUSOIDAL TIME VARIATIONS. 8-3-1 Solutions to the Transmission...
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<P(z)>= f<S (z >dS. z + As J- <PdL>. 2 <p>. Figure 8-16 A transmission line with lossy walls and dielectric results in waves that decay as they propagate. The spatial decay rate a of the fields is approximately proportional to the ratio of time average dissipated power per unit length <PL>. to the total time average electromagnetic power flow...
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Figure 8-20 (a) The load impedance at z = 0 reflected back to the source is found using the (b) Smith chart for various line lengths. 8-4-4 Standing Wave Parameters. The impedance and reflection coefficient are not easily directly measured at microwave frequencies. In practice, one slides an ac voltmeter across a slotted transmission line and measures the magnitude of...
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When the load is matched by the stub to the line, the VSWR to the left of the stub is unity, while to the right of the stub over the length 11the reflection coefficient is. Generally new elements can only be connected at the ends of the line and not inbetween.. 8-5-3 Double-Stub Matching. A match is made by adjusting...
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Similarly, the surface currents are found by the discontinuity in the tangential components of H to be purely z directed:. kkk2Eo sin kx. We see that if m or n are even, the surface charges and surface currents on opposite walls are of opposite sign, while if m or n are odd, they are of the same sign. This helps...
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The fields can be essentially confined to the dielectric over a frequency range if the speed of the wave in the dielectric is less than that outside. The z component of the wavenumber must be the same in all regions so that the boundary conditions can be met at each interface. All the other electric and magnetic field components can...
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A transmission line is excited by a voltage source Vo cos wt at z = -1. The transmission line is loaded with a purely reac- tive load with impedance jX at z = 0.. (a) Find the voltage and current distribution along the line.. (b) Find an expression for the resonant frequencies of the system if the load is capacitive...
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where we introduce the negative sign on the right-hand side so that V becomes the electric potential in a static situation when A is independent of time. the middle term on the left-hand side of (12) becomes zero so that the resulting relation between A and J, is the non-. Note that for static conditions, V A = 0, which...
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Figure 9-3 The strength of the electric field and power density due to a z-directed point dipole as a function of angle 0 is proportional to the length of the vector from the origin to the radiation pattern.. radiation pattern. As far as the dipole is concerned, this radiated power is lost in the same way as if it were...
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The radiation pattern is called end-fire because the power is maximum in the direction along the array, as shown in Figure 9-7e.. The array factor can be varied by changing the current magnitude or phase in the dipoles. In particular, we again focus on the solution in the 0 = w/2. The radiation pattern is proportional to the square of...
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We wish to find the properties of waves propagating within a linear dielectric medium that also has an Ohmic conductivity or.. What is the scalar potential?. (a) Find the vector and scalar potentials.. -a<z<a. (a) Find the scalar and vector potentials, inside and outside the sphere. Find the effective lengths, radiation resistances and line charge distributions for each of the...
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and electric field, 56-57. Coefficient of coupling, 415 Coercive electric field, 151 Coercive magnetic field, 356-357 Cole-Cole plot, 234. curvilinear coordinates, 31 cylindrical coordinates, 31-33 of electric field, 86. with surface current, 335-336 in uniform electric field, 273-277. curvilinear coordinates, 24 cylindrical coordinates, 24-26 of electric field, 83. Drift-diffusion conduction, 156-159 Earth, fair weather electric field, 195. electric field, 139...