Abstract
Electro Magnetic Compatibility (EMC) Chamber requires high performance absorber material to assure the quality of EMC chamber related to Radio Frequency (RF) shielding effectiveness of the corresponding chamber. RF shielding effectiveness is measured following EN 50147-1 testing method. EMC laboratory of BPPT (Indonesian Agency for the Assessment and Application of Technology uses polyurethane absorber material which absorbs the carbon-neoprene mixture to maintain consistent RF performance over a broad frequency band, especially in the frequency range of CISPR 22 radiated emission test between 30 MHz to 6 GHz, limits in CISPR 22 (Information technology equipment-radio disturbance characteristics-limits and methods of measurement). This paper proposes alternative absorber materials based on organic materials: rice husk, coconut husk, cotton and sawn wood crumbs. In the early phase of this research, the frequency under consideration are 900 MHz and 1800 MHz. These frequencies are mostly used by mobile phone devices, therefore at this phase the resulted organic material absorber may be used for alternative mobile phone casing before to be used as absorber material for EMC laboratory in a broader frequency band. The organic materials are produced by mixing them with cement, carbon, and resin. Free space testing method is used in the measurements. Results has shown a mixture of 50% coconut husk with resin absorb the most radiated emission in 900 MHz, while 30% of coconut husk will absorb the most radiated emission in 1800 MHz.
Highlights
Unintentional electromagnetic emission from household equipments, electronic gadgets, and the newly upcoming IoT (Internet of Things) becomes a potential disturbance in their environment, especially to other Information Telecommunication Equipments (ITE) and to human’s health
There are standard available to ensure that the radiated emission of any mobile phones comply to the limit regarding Specific Absorption Rate (SAR), which means the unwanted radiated emission from a mobile phone will not have a hazardous impact to human health
Measurement test for rice husk and wood saw husk with VNA for absorption capability has shown that a mixed layer of rice husk without any additional carbon (50 grams weight) may absorb radiated emission in 900 MHz by reflection loss of -21.779 dB
Summary
Unintentional electromagnetic emission from household equipments, electronic gadgets, and the newly upcoming IoT (Internet of Things) becomes a potential disturbance in their environment, especially to other Information Telecommunication Equipments (ITE) and to human’s health. There are already standard to ensure that ITE in the market is comply to a defined limit such as CISPR 22 [1], which means the radiated emission of this ITE will not disturb the other ITE in their surrounding. There are standard available to ensure that the radiated emission of any mobile phones comply to the limit regarding Specific Absorption Rate (SAR), which means the unwanted radiated emission from a mobile phone will not have a hazardous impact to human health. The limits given in the standards are sometimes not enough to ensure that our environment is free from the unwanted radiated emission, especially when a specific condition required such as in Compatibility Electromagnetic Chamber (EMC). BPPT EMC is a semi anechoic chamber with polyurethane absorbers as given in Figure 1, which is mainly functioned as a room, with reflection coefficient of the chamber absorbing walls approaching zero value, to represent a free space environment
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