Shape Sensitivity Analysis Of Microstrip Patch Antenna For Use In An Wireless Sensor Net

With the advancement of wireless communication systems, low cost, minimal weight, compact and low profile antennas are in great demand for both commercial and military applications. Furthermore, as the size of wireless hand-held devices shrinks, it is desirable to integrate the antenna directly on the chip package to cut down cost and provide flexible integration. Conformal low-profile antennas, such as printed dipoles, rectangular patches and slots, are widely used in large arrays on ground based, vehicular, air-borne and shipboard applications. Microstrip patches are usually used as radiating elements also in arrays and planar reflector antennas. These traditional resonant structures are typically half a wavelength in the critical dimensions and have relatively narrow bandwidth. In order to overcome these limitations, circular and annular shaped microstrip elements can be used, where the resonant dimension is related to half the circumference. This leads to a more compact solution, since for the same frequency the size of the patch is smaller. Another advantage of this solution is the possibility of working with double polarization. This paper investigates the performances of microstrip elements with circular annular shapes and suitable additional geometrical features, such as slots, to control the resonance behavior. In this work, both classical shapes (like rectangles, dipoles and rings) and the novel slotted annular patch are analyzed and compared. Figures of merit of the element performance are the bandwidth and the polarization. The shapes analyzed are suitable and versatile for use in a wireless net, both in the sensors and in the main receiver.