The explosive progress of electronic devices and communication systems results in the production of undesirable electromagnetic pollution, known as electromagnetic interference. The accumulation of electromagnetic radiation in space results in the malfunction of commercial and military electronic appliances, and it may have a negative impact on human health. Thus, the shielding of undesirable electromagnetic interference has become a serious concern of the modern society, and has been a very perspective field of research and development. This paper provides detailed insight into current trends in the advancement of various polymer-based materials with the effects of electromagnetic interference shielding. First, the theoretical aspects of shielding are outlined. Then, the comprehensive description of the structure, morphology and functionalization of the intrinsic conductive polymers, polymers filled with the different types of inorganic and organic fillers, as well as multifunctional polymer architectures are provided with respect to their conductive, dielectric, magnetic and shielding characteristics.

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Progress in polymers and polymer composites used as efficient materials for EMI shielding

The presented manuscript represents a miniaturized microstrip patch antenna with frequency and pattern reconfigurability. Three modes are analyzed based upon switching actions of two PIN diodes to achieve tunability. Low profile material FR-4 is used for the fabrication. The analysis is carried out in terms of tunability, reflectance response, resonance frequency, electric field, and bandwidth. The proposed structure provides tunability for the two bands. The proposed design provides the maximum tunability of 340 MHz, the bandwidth of 700 MHz, reflectance response of − 40.38 dB, an electric field of 4234.9 V/m, and beam tilting capability of 30°, − 40°, + 35°, − 90°, and 120°. Simulation and fabrication are carried out for the verification. The optimization of design is carried out by varying the dimensions of the three parameters. The comparison is also carried with previously published work. The proposed design can be used for multiband applications in the S and C bands.

Design and Verification of Novel Low-Profile Miniaturized Pattern and Frequency Tunable Microstrip Patch Antenna Using Two PIN Diodes

Polyaniline/V2O5 composites for anticorrosion and electromagnetic interference shielding

Using carbon-fibre-reinforced polymer (CFRP) composites for electromagnetic interference (EMI) shielding has become a rapidly emerging field. This state-of-the-art review summarises all the recent research advancements in the field of electromagnetic shielding properties of CFRP composites, with exclusive attention paid to experimental work. It focuses on (1) important mechanisms and physical phenomena in the shielding process for anisotropic carbon-fibre composites and (2) shielding performance of CFRP materials as reported in the literature, with important performance-affecting parameters. The key properties which directly influence the shielding performance are identified, the most critical being the carbon-fibre concentration along with length for discontinuous carbon-fibre-filled polymers and the lay-up for continuous carbon-fibre-reinforced composites. The effect of adding conductive inclusions such as metal or carbon nanotubes is also reviewed. It is emphasised that processing conditions are strongly linked with the shielding properties of a composite. This is a first review, which covers all the recent advancements in the field of shielding properties of carbon-fibre-reinforced composites, with detailed analysis of factors influencing these properties and clear distinction between continuous and discontinuous reinforcement. It is shown that CFRP composites make a good candidate as an EMI shielding enclosure material.

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Recent advances in electromagnetic interference shielding properties of carbon-fibre-reinforced polymer composites—a topical review

In this paper, a printed low-profile antenna with frequency and pattern reconfigurable functionality is designed in three modes. Each mode operates at different frequency bands and has several options available for pattern reconfiguration in these bands. The proposed antenna consists of eight pin-diode switches (S1 to S8). The switches S1 and S2, installed in the radiating patch, are used for frequency reconfigurability to control the operating bands of the antenna. The rest of the six switches (S3, S4, S5, S6, S7, and S8), loaded in the stubs on the rear side of the antenna, are used for pattern reconfiguration to control the main lobe beam steering. When all switches are off, the proposed antenna operates in a wideband mode, covering the 3.82-9.32 GHz frequency range. When S1 is on, the antenna resonates in the 3.5 GHz (3.09-4.17 GHz) band. When both S1 and S2 are on, the resonant band of the antenna is shifted to 2.5 GHz band (2.40-2.81 GHz). A very good impedance matching with a return loss of less than -10 dB is attained in these bands. The beam steering is done at each operating frequency by controlling the on and off states of the six pin-diode switches (S3, S4, S5, S6, S7, and S8). Depending on the state of the switches, the antenna can direct the beam in seven distinct directions at 4.2 GHz, 4.5 GHz, and 5 GHz. The main beam of the radiation pattern is steered in five different directions at 5.5 GHz, 3.5 GHz, and 2.6 GHz operating bands for the given state of the mentioned switches. The proposed antenna supports several sub-6 GHz 5G bands (2.6 GHz, 3.5 GHz, 4.2 GHz, 4.5 GHz, and 5 GHz) and can be used in handheld 5G devices.

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Design and Experimental Analysis of Multiband Compound Reconfigurable 5G Antenna for Sub-6 GHz Wireless Applications

Electromagnetic interference (EMI) is one of the biggest challenges faced during the production of any electronic device. The effect on the performance of the instrument due to these inevitable interferences must be carefully measured to understand and quantify the electromagnetic compatibility (EMC) of the instrument under test. If the EMI profile of the system does not meet the accepted standards, then it becomes necessary to take measures to reduce the influence of these unwanted interferences so that the equipment can be used in the real world. Unfortunately, research and studies on EMI and EMC have not received their due attention from the scientific community. Moreover, the literature available for this area of research is scattered where different sources provide information on one or more (but not all) aspects of EMI/EMC while ignoring the others. With the objective of encompassing this extremely significant area of research in its entirety, this review presents both EMI measurement techniques and EMI reduction techniques in detail. EMI measurement techniques are presented under two sections that deal with emission testing and immunity testing, respectively. Herein, EMI reduction techniques are presented under four sections, where electromagnetic shielding has been given special attention under which various methods used by the scientific community to measure the shielding effectiveness of a material or microwave absorber and its application in EMI reduction are illustrated. This is followed by EMI filters, circuit topology modification and spread spectrum. This review can help students and young scientists in this area to get an idea of the ways to conduct EMI tests as well as the ways that can be employed to reduce the EMI of the system, depending on the application.

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Electromagnetic Interference (EMI): Measurement and Reduction Techniques

A multi-purpose dual Multiple-Input-Multiple-Output (MIMO) antenna system for 5G mobile systems is presented in this paper. The proposed antenna consists of two sets of MIMO antennas on a single board. The 8-port MIMO antenna, placed on the board, is working over 3.5 GHz (3.4 GHz-3.6 GHz) 5G band with dimensions 150 mm $\times70$ mm. The 4-port MIMO system, placed on the chassis, is operating over 5.2 GHz WLAN/5.5 GHz WiMAX/5.8 GHz/6 GHz WiFi band with dimensions 20 mm $\times $ 7 mm. The prototype is designed and fabricated on FR4 ( $\epsilon _{r}=4.4$ and $\tan \delta =0.02$ ) substrate with 0.8 mm thickness. The overall design of the entire dual MIMO system is very minimal leaving ample space for other components to be placed on the board. The presence of two separate MIMO antennas in the proposed prototype aids in using the 5G frequencies and 4G frequencies independently. Since no active elements like diodes, switches etc. are involved in the proposed design to switch between different bands, the prototype is free from any ohmic losses. It is also worth noticing that the proposed antenna operates in the highly anticipated next generation WiFi 6E spectrum.

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Dual MIMO Antenna System for 5G Mobile Phones, 5.2 GHz WLAN, 5.5 GHz WiMAX and 5.8/6 GHz WiFi Applications

Mechanically frequency reconfigurable antenna for WSN, WLAN, and LTE 2500 based internet of things applications

A mechanical frequency reconfiguration technique in microstrip patch antennas for wireless sensor networks is presented in this paper. Frequency reconfiguration is achieved by mechanically changing the dielectric properties of the antenna and thereby obtaining a tunable frequency range from 2442 MHz to 2716 MHz. The gain of the prototype remains relatively flat throughout the reconfigured frequency range with a stable radiation pattern. The prototype is then studied as a fluid level sensor which operates based on the variation in resonant frequency with the rise or fall of the fluid in the dedicated channels engraved. The antenna is able to sense and transmit the information simultaneously with reduced complexity and less power consumption. Thus the proposed antenna could be used a fast wireless sensor for remote fluid level monitoring in wireless sensor networks.

Mechanically Frequency Reconfigurable Antenna and its Application as a Fluid Level Detector for Wireless Sensor Networks

The design and development of a new multi-directional switched beam antenna at 2.45 GHz for wireless sensor network applications is proposed in this paper. The beam of the antenna can be switched towards the boresight 00, at an angle of ± 800 in both azimuth and elevation planes. The two ports when excited with a 900 phase difference lead to a circular polarisation in the beam directed towards the boresight. It is also worth noting that the resonance frequency of the antenna remains within the 2:1 VSWR bandwidth irrespective of the direction of the switched beam.

Phalguni Mathur

Papers

Electromagnetic Interference (EMI): Measurement and Reduction Techniques

Dual MIMO Antenna System for 5G Mobile Phones, 5.2 GHz WLAN, 5.5 GHz WiMAX and 5.8/6 GHz WiFi Applications

Mechanically frequency reconfigurable antenna for WSN, WLAN, and LTE 2500 based internet of things applications

Mechanically Frequency Reconfigurable Antenna and its Application as a Fluid Level Detector for Wireless Sensor Networks

2.45 GHz Pattern Reconfigurable Antenna for Wireless Sensor Network applications