The mutual coupling between very low frequency (VLF) antenna elements is an important factor affecting the radiation performance of umbrella antenna arrays. This study evaluates the factors influencing the mutual coupling between the elements of an umbrella antenna array. We develop a mutual coupling analysis method for calculating the input impedances of a VLF antenna based on the impedance effect of mutual coupling. The radiation resistance of the VLF umbrella antenna can be obtained using numeric integral from Method of Moments (MoM) solution. Using the FEKO simulation software, a model of a trideco-tower umbrella antenna array is established. The electrical parameters of the VLF umbrella antenna array on inhomogeneous ground are calculated for both single and dual feeding modes. The impedance characteristics of the umbrella antenna arrays are also simulated for different array inter-element spacings on homogeneous ground. Representative numerical results are reported and discussed to assess the mutual coupling effect of the proposed method in comparison with full-wave simulations.
1. Li, H.-Y., J. Zhan, Z.-S. Wu, and P. Kong, "Numerical simulations of ELF/VLF wave generated by modulated beat-wave ionospheric heating in high latitude regions," Progress In Electromagnetics Research M, Vol. 50, 55-63, 2016. doi:10.2528/PIERM16062604
2. James, M., "Stripping very low frequency communication signals with minimum shift keying encoding from streamed time-domain electromagnetic data," Geophysics, Vol. 80, No. 6, 343-353, 2015. doi:10.1190/geo2015-0304.1
3. Aizebeokhai, A. P. and K. D. Oyeyemi, "Application of geoelectrical resistivity imaging and VLF-EM for subsurface characterization in a sedimentary terrain, Southwestern Nigeria," Arabian Journal of Geosciences, Vol. 8, No. 6, 4083-4099, 2015. doi:10.1007/s12517-014-1482-z
4. Hurdsman, D. E., P. M. Hansen, and J. W. Rockway, "LF and VLF antenna modeling," Antennas and Propagation Society International Symposium, Vol. 4, 811-814, IEEE, 2003.
5. Liu, C., Q. Z. Liu, L. G Zheng, and W. Yu, "Numeric calculation of input impedance for a giant VLF T-type antenna array," Progress In Electromagnetics Research, Vol. 75, 1-10, 2007. doi:10.2528/PIER07051701
6. Best, S. R., "A discussion on the properties of electrically small self-resonant wire antennas," IEEE Antennas and Propagation Magazine, Vol. 46, No. 6, 9-22, 2004. doi:10.1109/MAP.2004.1396731
7. Li, H. F. and C. Liu, "Calculation on characteristics of VLF umbrella inverted-cone transmitting antenna," 2014 Sixth International Conference on Ubiquitous and Future Networks (ICUFN), 389-391, Shanghai, 2014. doi:10.1109/ICUFN.2014.6876819
8. Li, H. and C. Liu, "Calculation on characteristics of VLF umbrella inverted-cone transmitting antenna," International Conference on Ubiquitous & Future Networks, 389-391, IEEE, July 2014.
9. Dong, Y., C. Liu, G. Dai, and Y. Yan, "VLF transmit antenna impedance characteristic based on top-Load configuration," Dianbo Kexue Xuebao/Chinese Journal of Radio Science, Vol. 29, No. 4, 763-768, 2014.
10. Liang, Z. X., et al., "Improved hybrid leapfrog ADI-FDTD method for simulating near-field coupling effects among multiple thin wire monopole antennas on a complex platform," IEEE Transactions on Electromagnetic Compatibility, Vol. 59, No. 2, 618-626, 2017. doi:10.1109/TEMC.2016.2632129
11. Kurs, A., et al., "Wireless power transfer via strongly coupled magnetic resonances," Science, Vol. 317, No. 5834, 83-86, AAAS, 2007. doi:10.1126/science.1143254
12. Huang, Q., H. Zhou, and X.-W. Shi, "A new compensating method for the mutual coupling effect in adaptive antenna arrays composed of wire elements," Progress In Electromagnetics Research C, Vol. 35, 221-236, 2013. doi:10.2528/PIERC12110804
13. Youndo, T., P. Jongmin, and N. Sangwook, "Mode-based analysis of resonant characteristics for near-field coupled small antennas," IEEE Antennas and Wireless Propagation Letters, Vol. 8, No. 4, 1238-1241, IEEE, 2009. doi:10.1109/LAWP.2009.2036133
14. Fallahi, R. and M. Roshandel, "Effect of mutual coupling and configuration of concentric circular array antenna on the signal-to-interference performance in CDMA systems," Progress In Electromagnetics Research, Vol. 76, 427-447, 2007. doi:10.2528/PIER07070104
15. Liao, B. and S. C. Chan, "A cumulant-based method for direction finding in uniform linear array with mutual coupling," IEEE Antennas and Wireless Propagation Letters, Vol. 13, 1717-1720, IEEE, August 2014. doi:10.1109/LAWP.2014.2352939
16. Gupta, I. J. and A. A. Ksienski, "Effect of mutual coupling on the performance of adaptive arrays," IEEE Transactions on Antennas and Propagation, Vol. 31, No. 5, 785-791, September 1983. doi:10.1109/TAP.1983.1143128
18. Ralchenko, M., M. Roper, M. Svilans, and C. Samson, "Coupling of very low frequency through-the- Earth radio signals to elongated conductors," IEEE Transactions on Antennas and Propagation, Vol. 65, No. 6, 3146-3153, 2017. doi:10.1109/TAP.2017.2694758
19. Balanis, C. A., Antenna Theory: Analysis and Design, 4th Ed., Wiley Press, Hoboken, 2016.
20. Rueda, C. I. P. and R. B. Miller, "A new approximate closed solution for small dipole antenna with method of moments," IEEE Latin America Transactions, Vol. 14, No. 4, 1562-1569, IEEE, 2016. doi:10.1109/TLA.2016.7483483
21. He, Q. Q. and B. Z. Wang, "Design of microstrip array antenna by using active element pattern technique combining with Taylor synthesis method," Progress In Electromagnetics Research, Vol. 80, 63-76, 2008. doi:10.2528/PIER07103006
22. Carlo, F. M. C. and B. Alessio, "Electromotive force induced in and inductance of an electrically small circular loop antenna," IEEE Transactions on Electromagnetic Compatibility, Vol. 56, No. 4, 780-783, August 2014. doi:10.1109/TEMC.2013.2280661
23. Carobbi, C. F. M. and A. Bonci, "Electromotive force induced in and inductance of an electrically small circular loop antenna," IEEE Transactions on Electromagnetic Compatibility, Vol. 56, No. 4, 780-783, 2012. doi:10.1109/TEMC.2013.2280661
24. Liu, C., H. Jiang, and J. H. Huang, Very Low Frequency Communication, Haichao Press, Beijing, 2008.
25. Jobava, R. G., et al., "Simulation of low-frequency magnetic fields in automotive EMC problems," IEEE Transactions on Electromagnetic Compatibility, Vol. 56, No. 6, 1420-1430, 2014. doi:10.1109/TEMC.2014.2325134
26. Taylor, D. and P. Loschialpo, "Imaging of helical surface wavemodes in the near field," Journal of Electromagnetic Waves and Application, Vol. 17, No. 11, 1593-1604, 2003. doi:10.1163/156939303772681451
27. Ubeda, E., J. M.Rius, and A. Heldring, "Nonconforming discretization of the electric-field integral equation for closed perfectly conducting objects," IEEE Transactions on Antennas and Propagation, Vol. 62, No. 8, 4171-4186, 2014. doi:10.1109/TAP.2014.2325954
28. Miller, E. K. and F. J. Dearick, "Some computational aspects of thin-wire modeling," Numerical and Asymptotic Techniques in Electromagnetics, Vol. 3, 89-127, Springer-Verlag, New York, July 2005.
29. Hatamzadeh-Varmazyar, S., M. Naser-Moghadasi, and Z. Masouri, "A moment method simulation of electromagnetic scattering from conducting bodies," Progress In Electromagnetics Research, Vol. 81, 99-119, 2008. doi:10.2528/PIER07122502
30. Huang, Q. L., Electrical Power Engineer’s Handbook, China Electric Power Press, Beijing, 2002.
31. Hansen, P. and J. Chavez, VLF Cutler: September 1997, Four-Panel Tests; RADHAZ and Field Strength Measurement, Space and Naval Warfare Systems Center, San Diego, 1997.
32. Hansen, P., "Terrestrial antenna for high power VLF radiation into the magnetosphere," General Assembly and Scientific Symposium (URSI GASS), 1-4, Beijing, 2014.