Microstrip Antenna in Mobile Phones

Microstrip antenna is being extensively used in mobile and other hand held communication devices. The microstrip antenna can be fabricated on the same printed circuit board containing the electronic components of the device. This leads to efficient use of the available space and making the device compact. This shows that, in the case of mobile or other small communicating devices, the size of the antenna plays a vital role. So, by reducing the size of antenna, the overall size of the device can be reduced. In recent years, as the demand of the small systems have increased, small size antennas at low frequency have drawn much interest from researchers. Many kind of miniaturization techniques, such as using of dielectric substrate of high permittivity, slot on the patch, DGS at the ground plane or a combination of them have been proposed and applied to microstrip patch antennas. The other method to miniaturize the microstrip antenna is to modify its geometry using irises or folded structures, based on the perturbation effect.

In this paper slots and DGS are used to miniaturize the rectangular microstrip antenna. The rapid development of wireless communication systems has increased the demand for compact microstrip antennas with high gain and wideband operating frequencies. Microstrip patch antenna has advantages such as low profile, conformal, light weight, simple realization process and low manufacturing cost. However, the general microstrip patch antennas have some disadvantages such as narrow bandwidth etc. Enhancement of the performance to cover the demanding bandwidth is necessary. There are numerous and well-known methods to increase the bandwidth of antennas, including increase of the substrate thickness, the use of a low dielectric substrate, the use of various impedance matching and feeding techniques.

A microstrip patch antenna consists of a radiating patch on one side of a dielectric substrate which has a ground plane on the other side. The patch is generally made of conducting material such as copper or gold and can take any possible shape. The radiating patch and the feed lines are usually photo etched on the dielectric substrate. In order to simplify analysis and performance prediction, the patch is generally square, rectangular, circular, triangular, and elliptical or some other common shape.

The present work deals with design and analysis of a rectangular compact microstrip antenna for wireless application. In this design, a combination of E shaped and T shaped slots are produced on the patch with some adjustments in the dimensions of ground structure. Initially the antenna is designed for the resonant frequency of 3 GHz and the using DGS and slots the resonant frequency is brought down to 0.9 GHz. So a size reduction of 86.72% is achieved.