SWITCHED Beam Smart Antenna steer the
optimum power towards the desired direction,
which is ideally suitable for Rural Mobile
communication where locality situated in discrete
sectorized manner in wide geographic plane.
The convenient base station antenna is 120° sectored. For this reason most of electromagnetic
pollution power is radiated in other directions than
towards the desirable user. Furthermore, the power
radiated in other directions is experienced as
interference by other users. The smart antenna uses
the base station antenna patterns directing a beam
towards the user of interest only. Consequently, SBSA
will lead to a much more efficient use of the power
and spectrum, increasing the useful received power as
well as reducing interference. The reason for SBSA
being widely applied during the past years is that the
new technologies of digital communications now are
available. It means, powerful digital signal processors
(DSP), more capacity and spectrum efficiency, and
new CDMA systems (e.g., IS-95 and UMTS) etc. In
addition to increased capacity, smart antennas also
introduce a number of new advantages to wireless
networks, including increased range, a higher level of
security, and the possibility for new services.
This paper presents the Switch Beam Smart
Antenna (SBSA) version of smart antenna. It starts
with an explanation of the basic principles of SBSA.
The Microstrip Patch Array SBSA is constructed and
its performance analysis is carried out.
___________________________________
Paper No 45C; Copyright © 2006 by the IETE. |
|
Fig 1 Switched beam array pattern
PHASED ARRAY ANTENNA
Usually radiation pattern of a single element is
relatively wide, and each element provides low value
of directivity(gain). In many applications it is necessary
to design antennas with very directive characteristics
to meet the demands of long distance communication
along with undesired radiation in undesired
direction.This can be accomplished by increasing the
electrical size of the antenna. Enlarging the dimensions
of single element often leads to more directive
characteristics. Another way to enlarge the dimensions
of the antenna ,without necessiarily increasing the
size of the individual elements, is to form an assembly
of radiating elements. This new antenna formed by
multielements , is referred to as an array.
To provide very directive patterns, it is necessary
that the fields from the elements of the array interfere
constructively(add) in the desired directions and
interfere destructively (cancel each other) in the
remaining space. |