24-11-2010, 10:21 AM
This article is spresented by:Professor R. Struzak
Basic Antenna Theory
Purpose
to refresh basic concepts related to the antenna physics
needed to understand better the operation and design of microwave links and systems
Outline
Introduction
Review of basic antenna types
Radiation pattern, gain, polarization
Equivalent circuit & radiation efficiency
Smart antennas
Some theory
Summary
Intended & unintended radiators
Antennas intended to produce specified EM field
Radiocommunication antennas; Measuring antennas; EM sensors, probes; EM applicators (Industrial, Medical, Scientific)
Radiators not intended to generate any EM field, but producing it as an unintended side-effect
Any conductor/ installation with varying electrical current (e.g. electrical installation of vehicles)
Any slot/ opening in the screen of a device/ cable carrying RF current
Any discontinuity in transmission medium (e.g. conducting structures/ installations) irradiated by EM waves
Stationary (e.g. antenna masts or power line wires); Time-varying (e.g. windmill or helicopter propellers); Transient (e.g. aeroplanes, missiles)
Antenna purpose
Transformation of a guided EM wave in transmission line (waveguide) into a freely propagating EM wave in space (or vice versa) with specified directional characteristics
Transformation from time-function in one-dimensional space into time-function in three dimensional space
The specific form of the radiated wave is defined by the antenna structure and the environment
for more information abut this topic please follow the link:
http://wireless.ictp.it/school_2005/lect...basics.ppt