EC-503-A Cntl - Dec 2025 Question Paper

Under each question, How to answer lists the points an answer should cover, outlined by CampusPrep from the syllabus. Check the details against your textbook.

1. 7 Marks
   aExplain symmetrical and asymmetrical attenuators.
   How to answer

   • Define attenuator and its purpose in networks
   • Explain symmetrical attenuator with equal image impedances both sides
   • Explain asymmetrical attenuator with unequal image impedances
   • Give examples - T, pi, lattice sections and applications
2. 7 Marks
   bExplain image transfer coefficient and iterative transfer coefficient.
   How to answer

   • Define transfer coefficient in two-port network theory
   • Explain image transfer coefficient with image impedances terminated
   • Explain iterative transfer coefficient with iterative impedances
   • Give relation/formula and physical significance
3. 7 Marks
   aWhat is filter specifications. Discuss passband, stopband, cut-off frequency, bandwidth, attenuation, ripple, and selectivity.
   How to answer

   • Define filter specifications
   • Explain passband, stopband and cut-off frequency
   • Explain bandwidth, attenuation, ripple and selectivity
   • Relate specifications to filter response curve
4. 7 Marks
   bExplain the Butterworth approximation.
   How to answer

   • Define Butterworth approximation and maximally flat concept
   • Explain magnitude-squared response formula
   • Explain pole locations and order vs selectivity
   • Mention advantages and applications
5. 7 Marks
   aExplain the concept of minimum positive real functions. Discuss their properties and significance in network synthesis.
   How to answer

   • Define positive real and minimum positive real functions
   • List properties - poles, zeros, real part conditions
   • Explain Hurwitz and realizability conditions
   • Explain significance in passive network synthesis
6. 7 Marks
   bExplain synthesis coefficients. Discuss their role and importance.
   How to answer

   • Define synthesis coefficients
   • Explain how they arise in expansion of PR functions
   • Discuss role in element value determination
   • Explain importance in Foster and Cauer realizations
7. 7 Marks
   aExplain the concept of an infinite transmission line.
   How to answer

   • Define infinite transmission line
   • Explain concept of infinite length and no reflection
   • Explain characteristic impedance as input impedance
   • Mention significance for analysis of finite lines
8. 7 Marks
   bDerive the expressions for voltage and current on a transmission line.
   How to answer

   • Start from differential R-L-G-C line model and telegrapher equations
   • Assume time-harmonic solution and propagation constant
   • Derive voltage and current expressions with incident and reflected waves
   • Define characteristic impedance and propagation coefficient
9. 7 Marks
   aExplain the circle diagram method for transmission line analysis. Discuss its importance in high-frequency applications.
   How to answer

   • Define circle diagram and reflection coefficient locus
   • Explain constant VSWR and constant impedance circles
   • Explain construction procedure for line analysis
   • Discuss use at high frequencies for matching and measurements
10. 7 Marks
    bExplain single stub and double stub matching techniques.
    How to answer

    • Define impedance matching need in transmission lines
    • Explain single-stub matching principle and design steps
    • Explain double-stub matching and advantage of fixed positions
    • Compare limitations and applications
11. 7 Marks
    aExplain the parameters of transmission lines and coaxial cables at radio frequencies.
    How to answer

    • Define primary constants R, L, G, C of line
    • Explain secondary constants Z0 and gamma at radio frequencies
    • Explain coaxial cable parameters and losses
    • Discuss frequency dependence and approximations
12. 7 Marks
    bExplain the Smith Chart. Describe its construction, properties, and significance in transmission line analysis.
    How to answer

    • Define Smith Chart and its basis in reflection coefficient plane
    • Explain construction of resistance and reactance circles
    • List properties - VSWR, impedance, admittance reading
    • Explain significance in matching and line analysis
13. 7 Marks
    aExplain the fundamentals of transmission lines.
    How to answer

    • Define transmission line and distributed parameters
    • Explain types - open wire, coaxial, microstrip etc.
    • Explain propagation, attenuation and distortionless condition
    • Mention characteristic impedance and applications
14. 7 Marks
    bExplain the concept of minimum positive real functions.
    How to answer

    • Define positive real and minimum positive real functions
    • Explain necessary and sufficient conditions
    • Give examples of testing PR property
    • Mention use in network realizability
15. 7 Marks
    aExplain the High Pass LC Filter.
    How to answer

    • Define high-pass LC filter and its function
    • Show T/pi circuit with series C and shunt L
    • Explain cut-off frequency and attenuation characteristic
    • Mention design formulas and applications
16. 7 Marks
    bExplain the characteristic parameters of two-port networks.
    How to answer

    • Define two-port network and characteristic parameters
    • Explain image and iterative impedances and transfer constants
    • Give ABCD parameter relations for symmetrical/asymmetrical networks
    • Mention measurement and cascade applications