Comparative study of two E-microstrip antennad with linear and circular polarizations

Abstract

A microstrip antenna is a kind of antenna used radiate ultra-high frequency signals , due to its advantages such as low weight , low profile planar configuration so it can conform to planer and non-planar surfaces which fits the shape design and needs of modern communication equipment . It has low fabrication costs and capability to integrate with microwave integrated circuits technology , the microstrip antenna shape flexibility enables mounting them on a rigid surface which makes them mechanically robust. Microstrip antennas can be mass produced using simple and inexpensive modern printed circuit board technologies, the use of printed circuit board manufacturing technologies also enables fabricating the feeding and matching networks with the antenna structure , from a designer point of view microstrip antenna present a wide range of options. The designer can vary the choice of the substrate type, the antenna structure , type of perturbation and the feeding technique to achieve the antennas design objective. Micostrip antennas have a narrow impedance bandwidth , low efficiency and they can only be used in low power applications . they also show high ohmic losses when used in an array structure . Polarization polarity given by microstrip antenna is poor , most microstrip antennas radiate only in half-space, because they are implemented on double sided laminates where on side is used as a ground . The half space radiation limits their use in some application , the research in microstrip antenna design mainly focus on how to overcome these disadvantages.