Antennas are key components of any wireless system. An antenna is a conductor that can transmit, send and receive Electromagnetic (microwave, radio or satellite) signals... Most antennas are resonant devices, which operate efficiently over a relative narrow frequency band. There are different types of antennas. The dipole antenna is the first type of antenna to be ever used and the simplest one to study and understand, it is a strait wire fed from the center. Directional antenna is used for antennas which radiates power in focused and specific direction. Microwave Antennas which include parabolic reflector and horn antennas and are used for high gain. The Microstrip patch antenna is a single layer design which commonly consists of four parts (ground plane, patch, the feeding part and substrate). Microstrip antennas, mostly referred to as patch antennas consists of a very thin metallic patch (usually copper or gold) placed a small fraction of a wavelength above a conducting ground plane, separated by a dielectric substrate. The radiating patch can be of any planar geometry e.g. circle, rectangle, square, elliptical, thin strip dipole, disc sector, triangular and circular ring. The radiating elements and the feed lines are usually etched on the dielectric substrate of a material.
Microstrip antennas have some advantages such as light weight, low cost etc and some disadvantages such as low bandwidth & efficiency. However there are different methods by which their efficiency and bandwidth can be improved. Microstrip patch antennas are low profile, conformable to planar and non planar surfaces, simple and inexpensive to manufacture using modern printed circuit technology, physically robust when mounted on rigid surfaces, compatible with compatible with microwave monolithic integrated circuits (MMIC) designs. They are very versatile in terms of resonant frequency, polarization, pattern and impedance when particular patch shape and mode are selected. Furthermore, by adding loads between the ground plane and the patch, like pins, varicap diode and varactor diodes, microstrip antennas with changing resonant frequency, impedance, polarization and pattern are to be designed.
The above performance and advantages of microstrip patch antennas such as low weight, high intensity, low profile and low cost made these antennas the accurate choice for wireless communication world. These antennas have the ability and capability to integrate with microwave circuits and therefore they are very well suited for different cell devices applications, navigation systems application and WLAN applications.
2. Design consideration for Microstrip rectangular antenna
Since recent multi-functionality is required for the use of antennas operating in multiple frequency bands. Therefore, in this paper the microstrip patch antenna candidate is selected to be an E-Shaped based on previous works.
 In which a...