Previous year question paper for NFTL (Diploma Electrical Engineering 3rd)

1. Networks (20 hrs)

1.1 Two port (four terminals) network: Basic concepts of the following terms:-

Symmetrical and asymmetrical networks: Balanced and unbalanced network;

T-network, π network, Ladder network; Lattice network; L-network and Bridge

T-network

1.2 Symmetrical Network:- Concept and significance of the terms characteristic

impedance, propagation constant, attenuation constant, phase shift constant

and insertion loss; - T-network; π Network

1.3 Asymmetrical Network- Concept and significance of iterative impedance, image

Impedance, Image transfer constant and insertion loss.

2. Attenuators (08 hrs)

2.1 Units of attenuation (Decibels and Nepers): General characteristics of

attenuators.

2.2 Analysis and design of simple attenuator of following types; Symmetrical T and

π type.

3. Filters (20 hrs)

3.1 Brief idea of the use of filter networks in different communication systems,

Concept of low pass, high pass, band pass and band stop filters.

3.2 Analysis of prototype Low and High pass(Tand π) filter .

3.3 -Impedance characteristics v/s frequency characteristics of a low and high pass

filter and their significance.

3.4 -Attenuation vs frequency; Phase shift vs frequency, Characteristics impedance

vs frequency of T and π Low and High pass filters and their significance.

3.5 -Simple design problems of prototype low & high pass section.

3.6 Limitation of prototype filters, need of m-derived filters. Brief idea of m- derived

Low and High filter (Tand π) section.

3.7 Crystal Filters; Crystal and its equivalent circuit. Special properties of

piezoelectric filters and their use.

3.8 Active Filters; Basic concept of active filters and their comparison with passive

filters. Basic idea of Butterworth filter.

4. Transmission Lines (16 hrs)

4.1 Transmission Lines, their types and applications.

4.2 Distributed constants, T and π representation of transmission line section.

4.3 Definition of characteristic impedance, propagation constant, attenuation 

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constant and phase shift constant.

4.4 Concept of infinite line.

4.5 Condition for minimum distortion and minimum attenuation of signal on the- line

and introduction to loading methods.

4.6 Concept of reflection and standing waves, definition of reflection coefficient,

SWR & VSWR and their relation (no derivation).

4.7 Concept of transmission lines at high frequencies.

4.8 Introduction to stubs. (Single, open and short stubs).