Design of a miniaturized HF conical monopole

• Main Author: Jiang, Dan
• Other Authors: Shen Zhongxiang
• Format: Final Year Project
• Language: English
• Published: 2013
• Subjects: DRNTU::Engineering::Electrical and electronic engineering::Antennas, wave guides, microwaves, radar, radio
• Online Access: http://hdl.handle.net/10356/54287
• Institution: Nanyang Technological University

HF antennas are typically very large in size due to its very long operating wavelength. The water loading miniaturization technique was researched in this paper. With the large permittivity difference between water and free space, the size could be reduced to 1/9 of the normal antenna size ideally speaking. However, the large permittivity of water could block the transmission of electromagnetic waves to free space. Because of the complexity of water characteristics, this loading method was seldom researched. This paper serves as a discovery process about the possible water-loaded structures and methods. Conical monopole is used as the basic antenna model. A transition was designed to realize the transmission of electromagnetic waves from coaxial line feed into water. The designed antenna and transition height is approximately λLF/44 with operating wavelength from 45MHz to 132MHz. Besides, a water-loaded structure is designed in the paper allowing electromagnetic waves transmission to surrounding free space with operating frequency from 58MHz to 116MHz.