An Experimental Analysis of EMI Shielding Effectiveness using Multi layered Metal Meshed Reinforced Sustainable Foam

Organic foams are fabricated using a general mixing process incorporated with fine grid metal mesh inside it. The physical and chemical properties and the electromagnetic shielding effectiveness of these foams are investigated. The FTIR results indicate the presence of different organic functional groups. The sample with copper mesh was found to have the best EMI shielding effectiveness followed by brass, iron, and steel meshed samples. The average return loss in dB for a singlelayered sample with copper mesh was found to be around 28.715 dB and the average shielding effectiveness was found to be around 29.006 dB in the range of 8-12 GHz. The multilayered mesh samples showed better results than single-layered samples. Keywords—Organic Foam, Electromagnetic Interference (EMI) Shielding, Frequency, Fine Metal mesh


I. INTRODUCTION
The increasing complexity of electronic devices or systems in the form of higher packing density for quick response has resulted in electromagnetic interference [1] . Electromagnetic interference (EMI) or Radiofrequency interference is the noise that is resulted due to unwanted radiated signals caused by a wide range of electronic devices. The problem of EMI becomes prominent with the increase in the complexity of electronic devices or systems which has a high packing density for a quick response. Thus, it not only affects the performance of the device but also causes its degradation [2]. So, it becomes important to research on the performance features of the potential EMI shielding materials [3][4][5].
The material chosen must not have any unfavorable impact on the performance of the equipment. It should not trade off the efficiency of the equipment with the EMI shielding or hinder any of its workings. So other properties of the material such as flexibility, mechanical and thermal stability must be decent enough to give it a real industrial application and not just theoretical concept [6], [11].
Considering all the factors reinforced organic foams are believed to serve the purpose. They are lightweight, flexible and eco-friendly. Four samples are synthesized with organic foam as the base and different metal meshes (Steel, Iron, Copper, Brass) as the reinforcement. Various techniques are used to obtain the properties of the samples and a Shielding Effectiveness test setup is used for testing the EMI shielding capability of the material. A comparative study has been carried out to contrast with different samples. After fixing the metal mesh on the fixture, a mixture of isocyanides and polyol of ratio 2:3 is put into the mold and the reaction is allowed to take place. The reaction is exothermic and carbon dioxide gas is released as a byproduct. In the multi-layered meshed foams, the distance between the adjacent meshes is 3mm.

B. EMI shielding test Setup
The electromagnetic interference (EMI) shielding effectiveness is measured by using an experimental setup consisting of a transmitter transmitting radiation of 8 GHz -12 GHz and a receiver. A spectrum analyzer is used to generate a plot of the Shielding Effectiveness (SE) of the sample being tested. In this setup, the transmitter and the receiver are placed 30 cm apart excluding sample thickness and the sample is placed in between as shown in the photograph. The plot is obtained on the analyzer for the frequency range of 8GHz -12GHz.

B. EMI Shielding Performance Test
The result of the EMI Shielding performance test was obtained in the form of a graph as shown in figures 8, 9, 10, 11 and 12. The results have been summarized in Table 1.   The negative value of shielding effectiveness merely represents the loss of EM wave power concerning the incident EM wave. The comparison should be made based on the absolute value of the shielding effectiveness. According to the graphs obtained from the EMI shielding effectiveness experiment, the foam with the copper mesh was found to have the maximum shielding effectiveness followed by brass, iron and steel sample.
The single layered samples have little less Shielding Effectiveness in comparison to multilayered samples. And among all, the samples with copper mesh have better SE followed by brass, Iron and steel which is around 32 dBs.
V. CONCLUSIONS The physical and chemical properties of the samples are found, and the shielding effectiveness is characterized using the EMI shielding test.
• The sample with copper mesh was found to have the maximum shielding effectiveness followed by the sample with brass, iron and steel meshes. • Multilayered samples have little more shielding effectiveness then single layered samples. • The machinability of the shielding material is improved because of the meshes. Now it is easy to shape the shielding material into different shapes and retain the same. • Thus, we can derive from our investigation that in the frequency range of 8 GHz-12 GHz the flexible foam with different meshes can be actively used to