Design and Analysis of a Novel Dielectric Loaded Helical Antenna for WLAN Applications

Helical antennas have been popular antenna configurations for various applications for its simple structure [9-10]. This paper describes the study on the best custom shape dielectric loaded helical antenna for Access Point WLAN IEEE 802.11 b/g 2.4 GHz to 2.48 GHz applications. This paper presents the investigation of a Novel helical antenna incorporated with Barium Strontium Titanate (BST). Methods and antenna assembly techniques are based on previous works[1-5]. This paper focuses on the parametric study of such antennas with the use of simulation tools using the CST Microwave Studio. The antenna impedance is optimized by varying the antenna geometrical parameters [14-15] and the dielectric loading [11] with the transient solver. The antenna design is optimized for operation with two of the WLAN Access Points (APs) already available in the market to determine its suitability for integration, as to provide an alternative to the manufacturers’ antennas. BST is a ferroelectric material. It has the potential to overcome all the limitations of MEMS, ferrite and MMIC phase shifters because it has an electric tunable dielectric constant [16]. It combines the lowloss properties of BST at microwave frequency with the distributed transmission line philosophy of the MEMS phase shifter which provides wide bandwidth and ease of design. BST was known to be a solid solution perovskite with a field-dependent permittivity and has been used in RF and microwave applications in the recent years [17]. High dielectric constant of BST would superbly reduce the dimension of the shaped required and decrease the helical antenna overall size. Other interesting aspects of BST are of its low dielectric loss, low leakage current, low temperature coefficient and the composition-dependent Curie temperature [18]. In a way, when fabricating BST into any shaped mould, heat applied would increase the dielectric constant from a few hundreds to thousands. This might happen due to the structure change from tetragonal to cubic perovskite structure involved.