课程名称︰电磁相容 课程性质︰选修 课程教师︰吴宗霖 开课学院：电资学院 开课系所︰电信所 考试日期（年月日）︰2007/12/07 考试时限（分钟）：2hrs 是否需发放奖励金：是 （如未明确表示，则不予发放） 试题 : 1.Determine the one sided Fourrier series expansion for the waveform in fig1. ↑ ︱x(t) ︱ ┼A ╱╲ ︱ ╱╲ ╱╲ 。。。 ╲╱ ╲︱╱ ╲╱ ╲。。。 —————————————──╪=═╪═╪——————──→ T/2 T Fig1 2.A 10-MHz clock oscillator having a 10 Ohm internal resistance has an open-circuit voltage waveform as a trapezoidal pulse train with a 50% duty cycle and rising and falling time of 2 ns. (a) Determine the value of a capacitor (an ideal one)that when places across the oscillator output will reduce the output voltage of the fifth harmonic by 10dB (b) Given that the open-circuit voltage transitions from 0 to 5V, estimate the level of this fifth harmonic and give the exact value. 3.A transmission line having L=200m , v=200 m/us , Zc=50 Ohm ,and RL= 20 Ohm is driven by a source that has Rs= 100 Ohm and an open-circuit source voltage that has rectangular pulse of 6V and duration 3 us. Sketch the imput current and output current for the line for a total time of 0≦t≦6us. 4.(a) Plot the LISN(Line Impedance Stabilization Network)circuit and illustrate the objective of the LISN. (B) Plot the equivalent circuit of common choke choke and explain how it fuctions. 5.(a) Show Friss transmission equation. (b) A lossless half-wave dipole is being driven by a 10-V(peak),50 Ohm source Determine the eletric field intensity at a distance of 10 km in a plane perpendicular to the antenna. 6.(a) Please derive the imput impedance of an infinite biconical antenna with a half angle θh ( Hint:∫ dx/sin(x) = -2ln[cot(a/2)] ) π-a (b) Please prove the radiation resistance is equal to the imput impedance for the infinite biconical antenna. --

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