Summary
International Symposium on Antennas and Propagation
2012
Session Number:3C2
Session:
Number:3C2-2
Enhance Efficiency of High Frequency Antennas Using Lossy Metamaterials
Florent Jangal,
pp.-
Publication Date:2012/10/29
Online ISSN:2188-5079
Summary:
It is well-known that low frequency waves are propagated beyond the Line-of-Sight. In the High Frequency (HF) band (i.e. between 3 MHz and 30 MHz), this property is turned to good account, by radar and communication systems, in order to cover very large areas. Two propagation modes have to be distinguished: the surface wave mode and the sky wave mode. Due to the soil vicinity, HF antennas are always radiating energy in the sky wave mode as well as in the surface wave mode. The issue is: how to select only the desired propagation mode and avoid energy waste in the unwanted mode? We are proposing here to use metamaterial approach to design specific antennas. Despite the losses, which cannot be neglected in HF, and according to metamaterial shape, the surface impedance can be fitted either to enhance radiation of surface waves or to further low elevation sky waves. As a consequence, we are able to overcome the issue of energy waste in the unwanted HF propagation mode.