ECT 401
microwave & antennas
Preamble
This course aims to impart knowledge on the basic parameters of antenna, design and working of various broad band antennas, arrays and its radiation patterns. It also introduces various microwave sources, their principle of operation and study of various microwave hybrid circuits and microwave semiconductor devices.
Course Outcomes
Understand the basic concept of antennas and its parameters
Analyze the far filed pattern of Short dipole and Half wave dipole antenna.
Design of various broad band antennas, arrays and its radiation patterns
Illustratethe principle of operation of cavity resonators and various microwave sources.
Explain various microwave hybrid circuits and microwave semiconductor devices.
Previous year question paper & schemes
Basic antenna parameters: gain, directivity, beam width and effective aperture calculations, effective height, wave polarization, radiation resistance, radiation efficiency, antenna field zones. Duality and Principles of reciprocity, Helmholtz theorem (derivation required), Field, directivity and radiation resistance of a short dipole and half wave dipole (far field derivation).
module 2
Broad band antenna: Principle of Log periodic antenna array and design, Helical antenna: types and design. Designof Microstrip RectangularPatchantennas and feeding methods. Principles of Horn, Parabolic dish antenna (expression for E, H and Gain without derivation), Mobile phone antenna – Inverted F antenna.
module 3
Arrays of point sources, field of two isotropic point sources, principle of pattern multiplication, linear arrays of ‘n’ isotropic point sources. Array factor, Grating lobes.DesignofBroadside,End fire andDolph Chebyshevarrays. Concept of Phase array.
module 4
Microwaves:Introduction, advantages, Cavity Resonators- Derivation of resonance frequency of Rectangular cavity. Single cavity klystron- Reflex Klystron Oscillators: Derivation of Power output, efficiency and admittance. Magnetron oscillators: Cylindrical magnetron, Cyclotron angular frequency, Power output and efficiency.Travelling Wave Tube: Slow wave structures, Helix TWT,Amplification process, Derivation of convection current, axialelectric field, wave modes and gain.
module 5
Microwave Hybrid circuits: Scattering parameters, Waveguide Tees- Magic tees, Hybrid rings. Formulation of S-matrix.Directional couplers: Two hole directional couplers, S-matrix. Circulators and Isolators. Phase Shifter. Microwave Semiconductor Devices: Amplifiers using MESFET. Principle of Gunn diodes: Different modes, Principle of operation Gunn Diode Oscillators.