# Measurement of Sonobuoy Transmitting Antenna System for Anti-Submarine Warfare

• Min Kyeong-Sik (Dept. of Radio Science & Engineering, Korea Maritime University)
• Published : 2005.06.01

#### Abstract

This paper describes the measured results of sonobuoy transmitting antenna system for anti-submarine warfare (ASW). Since radiation pattern and power density depend on impedance matching between transmitting RF part and antenna with termination resistance, design of matching circuit is very important for sonobuoy system performance. Matching circuit is designed by Smith chart using control of L and C. In standing wave ratio(SWR) measurement using Network Analyzer, SWR of antenna with matching circuit observed 1.5 below at the assigned VHF band. It shows very excellent performance comparison with conversional product that is used for the same object. The measured vertical and horizontal radiation patterns are also shown the satisfaction of military specifications. A drop out of sonobuoy system on the sea is happened when angle of elevation direction is over 10 degrees, and it is conformed that it takes less than I second return to original signal level. The required electric power density is $83\;mW/m^2$ in the military specification, and measured electric power density is observed over average $110\;mW/m^2$ at all frequency bands.

#### References

1. G. Gonzalez, Microwave Transistor Amplifiers Analysis and Design, Prentice Hall, 1997
2. C. A. Balanis, Antenna Theory Analysis and Design, John Wiley & Sons, 1997
3. Kyeong-Sik Min, Kyeong-Woo Im, and Young-Hwan Park, 'Performance of sonobuoy antenna compensated with impedance matching circuit at VHF band', 2003 Asia-Pacific Microwave Conference, Seoul, Korea, pp. 591-594, Nov. 2003
4. Kyeong-Sik Min, Young-Hwan Park, and Kyeong-Woo Im, 'Design for sonobuoy transmitting antenna for anti submarine warfare', 2004 International Symposium on Antennas and Propagation, Sendai, Japan, vol. 2, pp. 1201-1204, Aug. 2004
5. H. Arai, Measurement of Mobile Antenna Systems, Artech House, 2001
6. Thereza M. MacNamara, Handbook of Antennas for EMC, Artech House, 1995