The Microstrip Antenna (MSA) is a resonant structure that consists of a
dielectric substrate sandwiched between a metallic conducting patch and ground plane.
Various types of MSAs are available, such as rectangular, circular, square,
triangular, etc. for use at microwave frequencies (Bahl and Bhartia, 1981). In the recent
scenario, MSAs are widely used in microwave communication for many applications due to
their light weight, low costs, planar and compact structure. However, the
main disadvantage is their narrow bandwidth (Bahl and Bhartia, 1981). The easiest way
to increase the bandwidth of an MSA is to print the antenna on a thicker
substrate or decrease the dielectric constant of the substrate (Girish and Ray, 2002).
Several other methods are also available in the literature to increase bandwidth such as
use of slot loading (Wong, 2002), monopole techniques
(Kimouche et al., 2010), stacking of two patches (Ali Hussain and Abdulkareem, 2010).
Further in modern broadband communication systems and in radars,
antenna operating more than one band of frequencies is more useful. The antenna of
light weight, compact with high gain are more attractive and such antennas are
also needed for the wireless and phased array applications. The dual band antennas
are realized by using rectangular, circular, triangular patch geometries (Daniel
and Shevgoankar, 2005; Vishwakarma et al., 2006; and Ray et al., 2009). But the study on design of dual band antennas, variation of operating bandwidth,
enhancement of gain using slot on the patch, on the ground plane and use of parasitic strip
around the square patch is rarely found in literature. |
