EC6602 ANTENNA AND WAVE PROPAGATION PDF

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EC6602 ANTENNA AND WAVE PROPAGATION To give insight of the radiation phenomena...

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PIT ECE VI SEM

EC6602 ANTENNA AND WAVE PROPAGATION

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PIT ECE VI SEM

EC6602 ANTENNA AND WAVE PROPAGATION LTPC3003 OBJECTIVES: • To give insight of the radiation phenomena. • To give a thorough understanding of the radiation characteristics of different types of antennas • To create awareness about the different types of propagation of radio waves at different Frequencies UNIT I FUNDAMENTALS OF RADIATION 9 Definition of antenna parameters – Gain, Directivity, Effective aperture, Radiation Resistance, Band width, Beam width, Input Impedance. Matching – Baluns, Polarization mismatch, Antenna noise temperature, Radiation from oscillating dipole, Half wave dipole. Folded dipole, Yagi array. UNIT II APERTURE AND SLOT ANTENNAS 9 Radiation from rectangular apertures, Uniform and Tapered aperture, Horn antenna , Reflector antenna , Aperture blockage , Feeding structures , Slot antennas ,Microstrip antennas – Radiation mechanism – Application ,Numerical tool for antenna analysis UNIT III ANTENNA ARRAYS 9 N element linear array, Pattern multiplication, Broadside and End fire array – Concept of Phased arrays, Adaptive array, Basic principle of antenna Synthesis-Binomial array UNIT IV SPECIAL ANTENNAS 9 Principle of frequency independent antennas –Spiral antenna, Helical antenna, Log periodic. Modern antennas- Reconfigurable antenna, Active antenna, Dielectric antennas, Electronic band gap structure and applications, Antenna Measurements-Test Ranges, Measurement of Gain, Radiation pattern, Polarization, VSWR UNIT V PROPAGATION OF RADIO WAVES 9 Modes of propagation , Structure of atmosphere , Ground wave propagation , Tropospheric propagation , Duct propagation, Troposcatter propagation , Flat earth and Curved earth concept Sky wave propagation – Virtual height, critical frequency , Maximum usable frequency – Skip distance, Fading , Multi hop propagation TOTAL: 45 PERIODS OUTCOMES: Upon completion of the course, students will be able to: Explain the various types of antennas and wave propagation. Write about the radiation from a current element. Analyze the antenna arrays, aperture antennas and special antennas such as frequency independent and broad band TEXT BOOK: 1. John D Kraus,” Antennas for all Applications”, 3rd Edition, Mc Graw Hill, 2005.

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PIT ECE VI SEM REFERENCES: 1. Edward C.Jordan and Keith G.Balmain” Electromagnetic Waves and Radiating Systems” Prentice Hall of India, 2006 2. R.E.Collin,”Antennas and Radiowave Propagation”, Mc Graw Hill 1985. 3. Constantine.A.Balanis “Antenna Theory Analysis and Design”, Wiley Student Edition, 2006. 4. Rajeswari Chatterjee, “Antenna Theory and Practice” Revised Second Edition New Age International Publishers, 2006. 5. S. Drabowitch, “Modern Antennas” Second Edition, Springer Publications, 2007. 6. Robert S.Elliott “Antenna Theory and Design” Wiley Student Edition, 2006. 7. H.Sizun “Radio Wave Propagation for Telecommunication Applications”, First Indian Reprint, Springer Publications, 2007.

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PIT ECE VI SEM

Course Name: Antenna and wave propagation (EC-6602) Year of Study: 2016–2017 (R-2013) On completion of course students will be able to S. No. Statement Course outcome Apply fundamental parameters related to antenna and basics of wire antennas. CO1 1 CO2

Obtain information about basic theorem, design and analyse of aperture antenna

CO3

Apply antenna parameters, design and analyse antenna arrays.

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CO4

Apply, analyse and the design equations of special antennas for the low and high frequency applications

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CO5

Acquire knowledge of various types of radio wave propagation and basic parameter of radio waves

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PIT ECE VI SEM UNIT 1 FUNDAMENTALS OF RADIATION PART A

Definition of antenna parameters – Gain, Directivity, Effective aperture, Radiation Resistance, Band width, Beam width, Input Impedance. Matching – Baluns, Polarization mismatch, Antenna noise temperature, Radiation from oscillating dipole, Half wave dipole. Folded dipole, Yagi array. 1. Define Antenna. [Remember] An antenna is a structure that has been designed to radiate or receive electromagnetic waves. 2. Define an Isotropic Antenna. [Remember] An Isotropic Antenna is the one which radiate energy uniformly in all directions. 3. Define Radiation pattern. (NOV / DEC 2012) [Remember] An antenna radiation pattern is defined as a mathematical function or a graphical representation of the radiation properties of the antenna as a function of space coordinates. The radiation properties include power flux density, radiation intensity, field strength, directivity, phase or polarization. 4. What are the 2 types of radiation pattern? [Understand] The 2 types of radiation pattern are (a) Field pattern and (b) power pattern Field pattern: If the radiation from the antenna is expressed in terms of the field strength (either E or H), then the radiation pattern is called as field pattern. Power pattern: If the radiation pattern from the antenna is expressed in terms of power per unit area, then the resultant pattern is called power pattern.

Define Radiation resistance of antenna. (APRIL / MAY 2011) (MAY / JUNE 2016) [Remember] Radiation resistance is defined as a ‘Virtual resistance that does not exist physically but is a quantity coupling the antenna to distant region s of space via a transmission line’. 5.

6. Define half power beam width. (NOV / DEC 2012) [Remember] Half power beam width is defined as the angular width measured in the radiation pattern between points where the power is half of its maximum value. It is also called -3 dB beam width. 7. Define Radiation intensity. [Remember] The power radiated from an antenna per unit solid angle is called radiation intensity (U). Its unit is watts per steradian and it is independent of distance. 8. Define Directivity of Antenna. (APRIL / MAY 2011) (NOV. / DEC. 2011) [Remember] Directivity is defined as the ratio of Radiation intensity of test antenna in a given direction to radiation intensity of isotropic antenna. D = U/U0 Where U= Radiation intensity of test antenna U0 = Radiation intensity of Isotropic antenna’

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PIT ECE VI SEM It is also expressed as D 

4 U Prad

9. What is front to back ratio? [Remember] Front to Back Ratio (FBR) is defined as the ratio of power radiated in the desired direction to the power radiated in the opposite direction ie. FBR = power radiated in desired direction/power radiated in opposite direction 10. Define Antenna efficiency. [Remember] Antenna Efficiency is defined as the ratio of power radiated to the total input power applied to the antenna. Antenna efficiency, k = Prad/Pin (dimensionless) Where Prad - Radiated power in watts Pin- Input power in watts 11. Define Reciprocity principle. [Remember] Reciprocity principle is stated as follows,’ If an emf is applied to the terminals of antenna no. 1 and the current measured at the terminals of another antenna no. 2, then an equal current both in amplitude and phase will be obtained at the terminals of antenna no. 1 if the same emf is applied to the terminals of antenna no.2’ 12. What do you meant by Antenna aperture? [Understand] Antenna aperture or equivalent areas are those which are used to describe the power capturing characteristics of the antenna when a wave impinges on it. 13. Define Effective aperture. (NOV. / DEC. 2011) [Remember] Effective aperture is defined as the ratio of power received at the antenna load terminal to the pointing vector (power density) of the incident wave. Its unit is W/m2. 14. What is the relationship between effective aperture and directivity? [Remember] The relationship between effective aperture and directivity is D= 4πAe/λ2 15. Define antenna Gain. [Remember] Gain is defined as the ability of the antenna to concentrate the radiated power in a given direction or absorb effectively the incident power from that direction. 16. Define antenna beam-width. Antenna beam-width is an angular width in degrees, measured on the major lobe of its radiation pattern between points where the radiated power has fallen to half of its maximum value. It is a measure of directivity of an antenna. 17. Define antenna band-width. [Remember] The bandwidth of an antenna is defined as the range of frequencies on either side of a center frequency where the antenna characteristics such as input impedance, beam-width, polarization, side lobe level, gain, beam direction, radiation efficiency, and radiation pattern are within an acceptable value of those at the center frequency. 18. Define antenna input impedance. [Remember] An antenna input impedance is nothing but the impedance offered by the input terminals of the antenna.

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PIT ECE VI SEM 19. What is folded dipole[Understand] In folded dipole antenna, two half wave dipoles have been folded and joined together in parallel at the ends. 20. What is BALUN [Remember] A balun is a device that connects a balanced line to an unbalanced line. It is used to balance an unbalanced system. For example, balun connects a twisted pair cable with a coaxial cable. 21. What is polarization mismatch [Remember] Generally, the polarization of the receiving antenna is not the same as the polarization of the incident wave; this is called as polarization mismatch. 22. What is antenna noise temperature? [Remember] The antenna noise temperature is defined as temperature of far field region of space and near surroundings which are coupled to the antenna through radiation resistance. 23. Define Hertzian dipole. [Remember] Hertzian dipole is defined as a short linear conductor or short electric dipole whose length is very short compared to wave length (L...