SMART
ANTENNA
F
rom the past, people tried to perceive the nature. Eyes,
ears, nose, tongue and skin are the nature gifts for the
human to sense the nature. Among those, the eye is the
only organ which can receive “The light” (high-frequency
electromagnetic waves). So, technically the eye could be classified as
an antenna but it can’t transmit waves, only receiving. Therefore, the
eye can be considered as the first natural antenna that humans used.
The first experiment that involved the coupling of electricity &
magnetism was done by Faraday in 1831. The journey which started
from that step, has changed the world to an unbelievable state today.
Antennas have become increasingly important in our society. They
are used in our homes, institutes, workplaces, phones, cars, aircrafts,
ships, satellites and spacecrafts. The IEEE standard definition of the
term for antennas (IEEE std 145-1983) defines the antenna or aerial
as “A mean for radiating or receiving radio waves”. In other words, the
antenna is the transitional structure between free-space (or another
medium) and a guiding device.
With the development of antenna technology, the smart antenna
concept has drawn a lot of attention. The rapid growth of high-speed
ADC (Analog- to- Digital Converters) technology and computational
power for DSP (Digital Signal Processing) have also contributed
to the development of high-performance smart antennas. A smart
antenna system consists of multiple antenna elements with signal
processing capability to optimize its radiation pattern automatically
according to the signal environment. They have two main functions,
DOA estimation: Direction of Arrival of the signal is estimated
using Digital signal processing and optimization techniques (Ex:
MUSIC (MUltiple SIgnal Classification), ESPRIT (EStimation of Signal
Parameters via Rotational Invariance Technique) algorithm, etc.)
BEAMFORMING: Radiation pattern of the array antenna is changed
to the desired direction by changing phase angle of the receiving
12
Gauge Newsletter
University of Peradeniya
Source: www.davianart.com