LF antenna optimization over high impedance ground plane

This paper discusses the approach to make use of the four towers in the existing Sectionalized Loran Transmitting (SLT) antennas. Various configurations have been investigated to operate at lower frequency with reasonable behavior. Upward radiation is desired so horizontal polarization is used. A High Impedance Surface (HIS) is introduced between the antenna and the ground plane to improve performance at low frequency. The HIS is studied for several different antenna types (smaller than SLT) operated at 100 KHz, Several kinds of modification are made to the HIS to optimize performance. Combined with Electrical Small Antenna (ESA) the HIS with capacitive loading turns out to improve performance, giving wider bandwidth and efficiency enhancement.