This work is dedicated to the study and measurement of the electric and magnetic fields intensities in the vicinity of an antenna array that is used for broadcasting at medium frequencies. The far field distance of a radiating system is usually computed with 2D2/λ which is obtained from the geometry of the problem. Another method to obtain the far field distance using the wave impedance of the electromagnetic wave through the ratio of electric and magnetic field, has been measured and calculated theoretically. The classical and new method to compute the far field distance are compared in this paper in order to show the improves in the calculation.
The antenna array used in this work is a monopole plus a parasitic element at medium frequency, which generate a ground wave. Near the antenna, the electric field has vertical and radial components, and the areas are called the reactive near field and the radiated near field. The attenuation of the electric and magnetic fields due to the soil can be neglected for the near field study.
The prediction of the levels of field intensity is useful to analyze electromagnetic interference and electromagnetic compatibility. It is also important to verify the regulations of International Standard IEEE C95-1 and the Argentina Regulation 3690 of National Communications Commission (CNC).
Walter Gustavo Fano,
C. Grau Escriva,
"Near Field Characteristics of Mf Monopole with a Parasitic.," Progress In Electromagnetics Research Letters,
Vol. 5, 175-186, 2008. doi:10.2528/PIERL08112709
1. Jordan, E. C., Electromagnetic Waves and Radianting Systems, Prentice-Hall, New York, 1950.
2. Balanis, C. A., Advanced Electromagnetic Engineering, J. Wiley, Arizona, 1989.
3. Collin, R. E., Antennas and Radiowave Propagation, McGraw-Hill Book Company, 1985.
4. Trzaska, H., Electromagnetic Field Measurements in the Near Field, Noble Publishing, USA, 2001.
5. Trainotti, V. and W. G. Fano, Ingenieria Electromagnetica, Buenos Aires, Argentina, 2005.
6. Fano, W. G. and V. Trainotti, "Dielectric properties of soils," IEEE Conference on Electrical Insulation and Dielectric Phenomena, 75-78, 2001.
7. Lastname, F. M., "Simplified calculation of coverage area for MF AM broadcast stations," IEEE Antennas and Propagation Soc. Magazine, 41-44, 1990.
8. May, G. C. and G. W. Raffoul, "A simple matlab program to calculate the electric field levels in the near field of a monopole antenna," Electromagnetic Compatibility, 2004. EMC 2004. 2004 International Symposium, 326-329, 2004.
9. Harrison, C. W., D. T. Clayborne, E. A. Aronson, and M. L. Houston, "An accurate representation of the complete electromagnetic field in the vicinity of a base-driven cylindrical monopole," IEEE Trans. Electromagn. Compat., Vol. 12, No. 4, 1064-1076, 1970. doi:10.1109/TEMC.1970.303053
10. Green, F. M., "NBS field strength standards and measurements (30 Hz--1000 MHz)," Proc. of the IEEE, Vol. 55, No. 6, 970-981, 1967. doi:10.1109/PROC.1967.5711
11., "IEEE guide for measurements of electromagnetic properties of earth," IEEE Standards, i-53, 2002.