The Response of a Magnetic Fluid to Radio Frequency Electromagnetic Field

Abstract

Electromagnetic pollution generated by the electrical devices has been regarded as a new form of pollution, harmful to the society as air and water pollution. The operation of electronic devices in a polluted electromagnetic environment has caused electromagnetic interference to become important concerns. Devices that are vulnerable to interference must often be shielded to protect them from the effects of electromagnetic interference. In this work we describe an interaction of a magnetic fluid based on transformer oil with alternating magnetic field. The magnetic fluid was composed of a transformer oil and dispersed magnetite nanoparticles coated with oleic acid. Among the wide range of topics covered, we pay attention to an important field related to the absorption of electromagnetic field by magnetic fluid as a suitable candidate for applications where it is necessary to electrically isolate, remove excess of heat, and to shield electromagnetic fields. We present a method for the determination of shielding effectiveness of the magnetic fluid under high-frequency excitation conditions from 750 MHz to 3 GHz by means of magnetic near field measurements and analysis. Herein, we report the effect of magnetic volume fraction in the magnetic fluid and the effect of the sample thickness on the shielding effectiveness. We have found that the magnetic fluid has a frequency dependent "windows", characterized that either absorb the magnetic field, or facilitate penetration of the magnetic field through the barrier.

Would the Human Brain Be Able to Erect Specific Effects Due to the Magnetic Field Component of an Uhf Field via Magnetite Nanoparticles?

“…All of these depend on the size, shape, crystalline anisotropy, morphology and the degree of aggregation/agglomeration of nanoparticles [26][27][28][29][30][31][32][33][34]. It should be noted that, in the general case, a fourth mechanism is possible as well -the generation of Foucault (eddy) currents, consisting in resistive heating caused by a rapidly varying magnetic flux.…”

Numerical Study of the Shielding Properties of a Ferrofluid Taking Into Account Magnitophoresis and Particle Interaction

“…Other composites, based on textile materials with ferrofluid, with the purpose of shielding from the electromagnetic fields of a wide frequency range were developed and studied in [7]. Experimental measurements and analysis of the shielding effectiveness of a ferrofluid under radio frequency electromagnetic fields were performed in [5,6]. Moreover, in patent [13] a magnetic field measurement system was suggested and described.…”