Active and passive perture coupled microstrip antenna design

The wireless industry has experienced a significant growth in the past several years. There is an essential need for a light weight with a low profile and a good performance antenna for wireless application. In order to meet these demands, printed circuit patch antenna is one of the solutions to it. There are four feedings for microstrip antenna which can be categorized in contacting feed and non-contacting feed. For contacting feed, there are microstrip feed and coaxial feed while non-contacting feed are proximity feed and aperture coupled feed. However, for microstrip feed and coaxial feed, these antennas are characterized by bandwidth limitation, which is about 1-2%. To overcome this problem, aperture coupled microstrip antenna is discovered by the researchers for the purpose to improve antenna performance features such as bandwidth. Their features have met the essential need for wireless application which requires a light weight with a low profile and a good performance antenna. The structure consists of two substrates, one containing the radiating patch and other containing the feed network. A small aperture located under the patch allows coupling of the patch to the feed line which has the form of an open-circuited stub. The input impedance can be controlled by its size, position, and shape of the aperture and open-ended stub length. Besides that, its performance will also affected by the type of the antenna which comprise of active or passive. In this chapter, the aperture coupled microstrip antenna with different type is investigated in terms of its return loss, bandwidth and radiation pattern.