Miniaturization of Microstrip Patch Antenna Using CSRR

Abstract

In this paper a novel structure of metamaterial is proposed in order to miniaturize a rectangular microstrip patch antenna. The metamaterial is composed of two nested split octagons which are located on a 10 mmx10 mm Rogers RT/duroid 5880 with 0.7874 mm thickness and dielectric constant of 2.2. A 3X5 array of such metamaterials is placed on the patch antenna substrate. By using this metamaterial in the antenna structure, the dimension of this proposed antenna is reduced compared to a simple microstrip patch antenna. Simulation results for return loss and radiation pattern of both proposed and conventional antenna are shown and compared. I. Introduction The basic geometry of a microstrip patch antenna(MPA) consists of a metallic patch printed on a grounded substrate. Three commonly used feeding methods are coaxial feed, stripline feed, and aperture- coupled feed. The patch antenna idea was first proposed in the early 1950s, but it was not until the late 1970s that this type of antenna attracted serious attention of the antenna community. The microstrip patch antenna offers the advantages of low profile, conformability to a shaped surface, ease of fabrication, and compatibility with integrated circuit technology, but the basic geometry suffers from narrow bandwidth. Metamaterials are artificial structures, and their electromagnetic properties dont exist in nature. Employing metamaterials in microstrip antenna substrate will result in the improvement of the antenna parameters like bandwidth, gain, efficiency, etc. Additionally, it is possible to miniaturize the antenna as much as desired with these structures, without dealing with surface waves problems. To date, many different techniques have been proposed, based on the use of metamaterials. Applications of double negative (DNG) and single negative (SNG) metamaterials have been widely studied by some research groups in miniaturization of subwavelength cavities, waveguides , and antennas. (6)This project present the possibility of miniaturization of a rectangular microstrip patch antenna by using a novel structure of metamaterial, which is placed on the substrate(1). With the advent and popularity of many wireless services, a quandary has arisen in the antenna community about how to develop small antennas that can satisfy the performance requirements for these systems as well as be aesthetically pleasing to the user. It is interesting to note that the latter point is not insignificant. As with the computer industry, mobile communications is very much a customer-driven market and thus the user requests, although technically with little merit, must be addressed. Ideally, an antenna that is unobtrusive and low cost, and can be located within thecasing of the handset would ensure the compactness of the handset terminal and therefore please the users. Microstrip antennas would appear to be possible candidates because of several attractive features, including their low profile, light weight, and ease of fabrication. Unfortunately, most present-day mobile communication systems are in the lower microwave region of the spectrum (less than 3 GHz) where these antennas in their conventional form are too large for wireless communication handsets. Several approaches have been reported to effectively reduce the size of the printed conductor of a microstrip patch antenna,here a new concept,that is the presence of metamaterial is used.(2) In this paper, we present the possibility of miniaturization of a rectangular microstrip patch antenna by using a novel structure of metamaterial, which is placed on the substrate.(3) First of all, designed a conventional rectangular patch antenna and analysed it. Then the resonance structure of the metamaterial is investigated and analyzed. Then the antenna structure at the presence of this metamaterial in the substrate is investigated and the return loss and radiation pattern of the proposed antenna is compared with the conventional patch antenna with the same dimension.(10)