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Phys 325: Communication Electronics I Question Paper

Phys 325: Communication Electronics I

Course:Bachelor Of Science

Institution: Chuka University question papers

Exam Year:2013

CHUKA

UNIVERSITY

UNIVERSITY EXAMINATIONS
EXAMINATIONS FOR THE AWARD OF DEGREE OF
BACHELOR OF EDUCATION (SCIENCE) AND BACHLOER OF SCIENCE (GENERAL)
PHYS 325: COMMUNICATION ELECTRONICS I
STREAMS: BSC, BED(SCIENCE) TIME: 2 HOURS
DAY/DATE: WEDNESDAY24/4/2013 8.30 AM – 10.30 AM
INSTRUCTIONS:

Answer Question ONE and any other TWO Questions

QUESTION ONE

(a) State the characteristic impedance of a low pass filter in attenuation Band. [2 Marks]

(b) What does the real part of the propagation constant show: [2 Marks]

(c) What is the purpose of an Attenuator? [2 Marks]

(d) What is Millman’s theorem applied to determine? [2 Marks]

(e) Give two characteristics of pass filters. [2 Marks]

(f) What is compensation theorem applicable to? [2 Marks]

(g) When is a network function said to have simple pole or simple zero? [2 Marks]

(h) State sampling theorem. [3 Marks]

(i) Give the interpolation formula for the reconstruction of the original signal g(t) form the sequence of sample values.{g(n/2W)}. [3 Marks]

(j) What is meant by PCM? [3 Marks]

(k) Define quantizing process and state the two fold effects quantizing process.
[3 Marks]
(l) What is meant by idle channel noise? [2 Marks]

(m) What is PAM? [2 Marks]

QUESTION TWO

(a) Open and short circuit impedances of a transmission line at 1.6 KHz are
900?-30°O and 400°?-10°O calculate the characteristic impendence
of the line. [8 Marks]

(b) In a symmetrical T-network, if the ratio of input and output power is 6.76. Calculate the attenuation in Neper & dB. Also design this attenuator operating between source and load resistances of 1000O. [12 Marks]

QUESTION THREE

(a) It is required to match 300 O load to a 400 O transmission line, to reduce the VSWR along the line to 1.0. Design a quarter-wave transformer at 100 MHz [8 Marks]

(b) A low-loss coaxial cable of characteristic impedance of 100 O is terminated in a
resistive load of 150 O. The peak voltage across the load is found to be 30 volts.
Calculate,

(i) The reflection coefficient of the load,
(ii) The amplitude of the forward and reflected voltage waves and current waves.
(iii) And V.S.W.R [12 Marks]

QUESTION FOUR

(a) Describe various types of losses in a transmission line. How are these losses are
reduced? [10 Marks]

(b) State the Millman theorem and prove its validity by taking a suitable example.
[10 Marks]

QUSTION FIVE

(a) What are the disadvantages of the prototype filters? How are they removed in composite filters? [10 Marks]

(b) Draw the equivalent circuit of a section of transmission line. Explain primary and secondary parameters. [10 Marks]
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Phys 325: Communication Electronics I Question Paper

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