BASICS OF ANTENNAS. Sruthi Dinesh, Research Engineer Deshila Technology Research Institute SJCE-STEP, Mysuru.
1/21/2022. Antennas are the eyes and ears of wireless communication whose function is to generate radio waves..
. 1/21/2022. E4ctr•rvetie epectrcr — Incresing wavelength Microwave ncreas ng Infra-Red uency Visible light ng ng« Ultra Violet X-rays Gamma rays Radio Waves Microwaves Visible Ultraviolet X-rays Gamma rays Broadcasting. communications and satellite transmission Cooking, communications and satellite transmission Cooking, thermal imaging, short-rarv communication, optical fibres, television remote controls and security systems Vision, and illumination Seurity marking. fluorescent lamps. detecting forged bank and disinfecting water Observing internal structure of objets, airport security scanners and medical x-rays Sterilising food and medical detection Of cancer and its treatment.
. 1/21/2022. Radio frequency range: 3 kHz to 300 GHz Microwaves : Subclass of radio waves ( 300 MHz to 300 GHz) Millimetre waves : 30 to 300 GHz At radio frequencies (20 kHz to 300 GHz), wavelength is very small approximately equal to component size. So current not confined to elements, but tends to radiate out as waves..
1/21/2022. What is an antenna ?? Antenna is a metallic device capable of radiating and receiving electromagnetic waves. It is a transducer which converts alternating current to radio frequency fields at transmitter side and vice-versa at receiver side. Transitional structure between free space and guiding device or transmission line (coaxial line or waveguide)..
. 1/21/2022. Transmission line Antenna Radiated free-space wave.
. 1/21/2022. How do Antennas radiate?. Accelerated or decelerated charges only can create electromagnetic waves. Satisfied by current with time harmonic variation ( AC current)..
. 1/21/2022. V.E €0 Ot Ot (1) (2) (3) (4) Gauss' law Magnetic monopoles Faraday's law Ampere-Maxwell law.
. 1/21/2022. Picture courtesy: Commtech Academy. DTRI | © 2022.
. 1/21/2022. Picture courtesy: Commtech Academy. DTRI | © 2022.
. 1/21/2022. Electric field created between the conductors.
. 1/21/2022. Alternating current produces magnetic field.