High frequency antenna design

• Main Author: Aditya Sunil Nalkur
• Other Authors: Lee Yee Hui
• Format: Final Year Project
• Language: English
• Published: 2016
• Subjects: DRNTU::Engineering
• Online Access: http://hdl.handle.net/10356/67516
• Institution: Nanyang Technological University

This paper presents a study of using seawater as a material for a quarter wave monopole antenna for use in the High frequency range of 3-30MHz. Traditional monopoles are usually made of metals such as copper and aluminium and are excited by an electric coil. However, in this paper, the current probe is designed to be able to excite the seawater antenna stream as it passes through the monopole to transform it into an antenna for communication purposes. The current probe was designed using the CSTMWS software and tested using a PEC antenna. The number of turns of coil were varied and the results were tabulated. The return loss results showed that using 200 turns of winding wire gave optimal results. The antenna material was then changed to seawater and simulations were done by varying seawater antenna radius and the conductivity of the seawater. Varying the thickness of the seawater antenna showed that both the return loss and gain of the antenna improved as the radius increases. Also, increasing the conductivity increased the gain of the antenna but the return loss performance become poorer. An experiment was also carried out for four test frequencies and the results were compared against the simulations performed for the seawater monopole antenna. The gain for the seawater antenna obtained from the experiment was very similar to the simulations. Recommendations have also been made to improve the performance of this seawater monopole antenna. Effectively, this study did indeed show that seawater is a possible material for use as an antenna and with more research, could replace metallic antennae in the future.