IETE Technical Review
Vol 23, No 5, September-October 2006, 2006, pp 293-296

Switched Beam Array Antenna for Sectorized
Optimum Power Distribution into Discrete
Localities of Rural Area

MAINAK MUKHOPADHYAY, AMIETE, ATANU ROY,
BINAY KUMAR SARKAR, AND AJAY CHAKRABARTY

Department E&ECE, Indian Institute of Technology, Kharagpur, 721 302, India.

The technology of Switched Beam Array Antenna for mobile communications has received enormous interest worldwide in recent decade. This type of smart antenna (another type is Adaptive Array Antenna) forms a pattern that adapts to the current radio conditions improving the communication link. The principal reason for applying Switched Beam Array Antenna is the possibility for a large increase in capacity and to introduce new services. The purpose of this paper is to give a performance analysis of Switch Beam Smart Antenna (SBSA) using micro strip patch elements with simulation results obtained by using CST Microwave StudioTM, in KCSTC of IIT Kharagpur.

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.

293