**Abstract**

Electromagnetic interferences (EMI) can cause different kinds of problems in digital and analog systems, leading to malfunctions, system reboots, or even permanent damage to the system if this is not adequately designed or protected. Nowadays, most electronic products are connected to the main power network or are designed to be interconnected with others through cables. These cable interconnections are becoming more difficult due to the rigid restrictions related to the accomplishment of electromagnetic compatibility (EMC) compliance. When the cables of a system represent an EMI source, it cannot pass the conducted or radiated emissions test. A widely used technique to reduce these problems is applying an EMI suppressor such as a sleeve core. This EMI suppressor provides selective attenuation of undesired interference components that the designer may wish to suppress, and it does not significantly affect the intended signal. This contribution focuses on analyzing different nanocrystalline (NC) EMI suppressors' performance intended for attenuating interferences in cables. Some NC novel samples are characterized and compare to MnZn and NiZn cores to determine this novel material's effectiveness compared to the conventional ceramic solutions by analyzing samples with different dimensions.

**Keywords:** electromagnetic interference (EMI) suppressors, electromagnetic compatibility (EMC), nanocrystalline (NC), cable filtering, relative permeability, impedance, insertion loss

### **1. Introduction**

Electromagnetic interference (EMI) can be defined as electromagnetic signals that unintentionally disturb an electrical or electronic system's normal operation. These perturbances can affect the electrical or magnetic magnitudes (voltage, current or electromagnetic field) of its circuits.

The problem of interferences is an issue that design engineers continually face [1]. Electromagnetic interferences can cause different kinds of problems in digital and analog systems, leading to malfunctions, system reboots, or even permanent damage to the system if the system is not adequately designed or protected [2]. The security of an electronic system in which coexist devices that produce electromagnetic interference and small signal circuits that can sensitive to these disturbances,

depends on the compatibility of the signal levels used.. Thereby, it is convenient to comply with specific design and installation rules that allow making the disturbance levels generated by the interferences source elements compatible with the signal levels used by the possible victim elements or elements sensitive to such interferences [3].

Some standards establish the maximum limits of interferences to ensure that the equipment is compatible and does not interfere. Thus, electromagnetic compatibility (EMC) is the ability of a system to operate satisfactorily in its electromagnetic environment without introducing disturbances above the normalized limits in that environment and withstanding those produced by other equipment. Electromagnetic compatibility is regulated by standards that require compliance with the limits of electromagnetic interferences in electronic systems by studying all the phenomena of generation, propagation, and susceptibility to EMI. Thereby, it is necessary to carry out measurements to certify that this equipment complies with regulations to meet these electronic equipment requirements.

When analyzing an EMI problem, the following elements should be identified (**Figure 1**): the source of interferences, the path of propagation, and receivers affected by the interferences. Based on this concept, when a designer faces an EMI problem, he/she must analyze the system, identify these three elements, and deal with interferences applying these strategies: eliminate EMI sources, increase the EMI immunity of the victim element and/or decrease the energy transmitted through the propagation path.

EMI can spread through different means or paths, as shown in **Figure 2**, so they can be grouped into:


The most appropriate strategy is to consider electromagnetic compatibility during the system design stage. If EMC is ignored until the problem arises during the first functional tests or product certification, the solutions usually result in a higher cost [4]. The possibility of applying specific techniques for the elimination of interferences is reduced as a system is developed. At the same time, the cost of EMI reduction increases [5]. However, it is not always possible to predict EMI problems during the design stage because it is complicated to emulate the real environment in

**69**

*Characterization of Nanocrystalline Cores for EMI Suppression in Cables*

which the system will work. Another possibility is that the designed system complies with the standards, but the problems appear when interconnected with other equipment or facilities. When this situation occurs, the right approach is to suppress EMI at its source whenever possible, rather than increasing immunity through victim circuit protections. This technique works best since a single EMI source can find multiple spread paths and affect different victims. If it is not possible to act directly on the source, it is recommended to focus on the EMI propagation path or,

Detection and correct characterization of the EMI is an essential factor in designing a suitable solution. Thus, it is essential to perform EMI measurements using different instrumentation, measuring probes, and antennas to detect the electromagnetic fields that can provide information to the designer from undesired signals. These measurements make it possible to detect the disturbances' magnitude and localize their frequency range in order to select the most optimal solution. When the cables represent the EMI source, it could not pass the conducted or radiated emissions test. A widely used technique to reduce these problems is apply-

This contribution focuses on analyzing different nanocrystalline (NC) EMI suppressors' performance intended for attenuating interferences in cables. Firstly, some applications of this kind of EMC components are described in section 2, while the description of the manufacturing process and main features of NC material are explained in section 3. The characterization methods employed to determine the NC samples' effectiveness from the standpoint of the impedance and insertion loss they can provide are shown in section 4. Subsequently, in section 5, NC sleeve cores' performance is discussed and compared to conventional ceramic samples. Finally,

The Magnetic Field (H) is associated with electrodynamic phenomena and appears whenever there are electric currents. The H field can produce effects capable of seriously disturbing the operation of an electronic circuit. Whenever current flows in a circuit, this current creates a magnetic field in that circuit, which will vary as the current varies. Consequently, in any circuit that carries an alternating current, variations of magnetic flux occur. According to Lenz's law, an

*DOI: http://dx.doi.org/10.5772/intechopen.96694*

finally, on the affected receiver.

**Figure 2.**

ing an EMI suppressor such as a sleeve core [5].

*Kind of propagation and coupling of electromagnetic interference.*

the main conclusions are summarized in section 6.

**2. Applications of EMI suppressor sleeve cores**

**Figure 1.**

*Main elements in electromagnetic interference phenomena.*

*Characterization of Nanocrystalline Cores for EMI Suppression in Cables DOI: http://dx.doi.org/10.5772/intechopen.96694*

**Figure 2.** *Kind of propagation and coupling of electromagnetic interference.*

*Materials at the Nanoscale*

interferences [3].

through the propagation path.

cables, metal chassis.

by a magnetic or electric field, respectively.

*Main elements in electromagnetic interference phenomena.*

can be grouped into:

depends on the compatibility of the signal levels used.. Thereby, it is convenient to comply with specific design and installation rules that allow making the disturbance levels generated by the interferences source elements compatible with the signal levels used by the possible victim elements or elements sensitive to such

Some standards establish the maximum limits of interferences to ensure that the equipment is compatible and does not interfere. Thus, electromagnetic compatibility (EMC) is the ability of a system to operate satisfactorily in its electromagnetic environment without introducing disturbances above the normalized limits in that environment and withstanding those produced by other equipment. Electromagnetic compatibility is regulated by standards that require compliance with the limits of electromagnetic interferences in electronic systems by studying all the phenomena of generation, propagation, and susceptibility to EMI. Thereby, it is necessary to carry out measurements to certify that this equipment complies

When analyzing an EMI problem, the following elements should be identified (**Figure 1**): the source of interferences, the path of propagation, and receivers affected by the interferences. Based on this concept, when a designer faces an EMI problem, he/she must analyze the system, identify these three elements, and deal with interferences applying these strategies: eliminate EMI sources, increase the EMI immunity of the victim element and/or decrease the energy transmitted

EMI can spread through different means or paths, as shown in **Figure 2**, so they

• Conducted interference: when the propagation path is an electrical conductor that joins the sources with the affected receiver such as power cables, signal

• Radiated interferences: they can be classified as far- or near-field depending on the propagation's wavelength and the distance between the source and victim elements. Radiated far-field interferences are identified when carried out through electromagnetic fields, fulfilling the following condition: propagation distance > wavelength/2π. Radiated near-field interferences are called coupling and can be identified as inductive coupling or capacitive coupling between neighboring conductors, depending on whether the interference is propagated

The most appropriate strategy is to consider electromagnetic compatibility during the system design stage. If EMC is ignored until the problem arises during the first functional tests or product certification, the solutions usually result in a higher cost [4]. The possibility of applying specific techniques for the elimination of interferences is reduced as a system is developed. At the same time, the cost of EMI reduction increases [5]. However, it is not always possible to predict EMI problems during the design stage because it is complicated to emulate the real environment in

with regulations to meet these electronic equipment requirements.

**68**

**Figure 1.**

which the system will work. Another possibility is that the designed system complies with the standards, but the problems appear when interconnected with other equipment or facilities. When this situation occurs, the right approach is to suppress EMI at its source whenever possible, rather than increasing immunity through victim circuit protections. This technique works best since a single EMI source can find multiple spread paths and affect different victims. If it is not possible to act directly on the source, it is recommended to focus on the EMI propagation path or, finally, on the affected receiver.

Detection and correct characterization of the EMI is an essential factor in designing a suitable solution. Thus, it is essential to perform EMI measurements using different instrumentation, measuring probes, and antennas to detect the electromagnetic fields that can provide information to the designer from undesired signals. These measurements make it possible to detect the disturbances' magnitude and localize their frequency range in order to select the most optimal solution.

When the cables represent the EMI source, it could not pass the conducted or radiated emissions test. A widely used technique to reduce these problems is applying an EMI suppressor such as a sleeve core [5].

This contribution focuses on analyzing different nanocrystalline (NC) EMI suppressors' performance intended for attenuating interferences in cables. Firstly, some applications of this kind of EMC components are described in section 2, while the description of the manufacturing process and main features of NC material are explained in section 3. The characterization methods employed to determine the NC samples' effectiveness from the standpoint of the impedance and insertion loss they can provide are shown in section 4. Subsequently, in section 5, NC sleeve cores' performance is discussed and compared to conventional ceramic samples. Finally, the main conclusions are summarized in section 6.
