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Investigation of oil palm ash microwave absorber for broadband application
Abstract
The investigation of oil palm ash microwave absorbers involves the design, simulation and fabrication of an effective broadband frequency for anechoic chamber. The resistive and magnetic materials in the oil palm ash compose its potential to be used as microwave absorbing materials. These oil palm ash absorbers are simulated using CST Microwave Studio. The arch measurement is executed to investigate the reflectivity performance of the oil palm ash absorbers. These absorbers are designed to operate effectively between the frequencies of 8 GHz and 12 GHz for broadband application.
... Biowaste such as bagasse is a very efficient material for microwave absorption and is reported better than rice husks due to its more carbon content. Noordin et al. (2012) reported the fabrication of microwave absorber using oil palm ash. The chemical composition of oil palm ash consists of CaO, MgO, SO 3 , K 2 O, SiO 2 , Fe 2 O 3 and CO 2 . ...
... ), banana leaves(Noordin et al. 2012), dried banana leaves(Kaur et al. 2015), agriculture waste (banana leaves/rice husk/rice straw, wheat straw)(Ma et al. 2019), rice husk(Nornikman et al. 2011), coconut shells(Salleh et al. 2011), tea waste(Akgül et al. 2019), peanut and hazelnut shells ...
The materials used in electrical and electronic applications have great importance and broader applications, but they have severe electromagnetic interference (EMI). These materials have extensive applications in broadcasting, medical industries, research, defence sectors, communication and similar fields. The EMI can be addressed by using effective EMI shielding materials. This review presents a detailed, comprehensive description for making electromagnetic interference shielding material by recycling various wastes. It starts with highlighting the overview of electromagnetic interference shielding (EMI) and its theoretical aspects. It provides a comprehensive and detailed understanding of recent trends in the novel approaches towards fabricating EMI shielding from industrial waste, agricultural waste and other miscellaneous wastes. This paper critically reviews the works related to the recycling of wastes like red mud (waste from the aluminium refining industry), ground tyre rubber, tea waste (biowaste) from tea industries, bagasse (waste from sugar cane industry), peanut and hazelnut shells (agricultural waste), waste tissue paper and polyethylene and other miscellaneous wastes like hydrocarbon carbon black and ash for the fabrication of highly effective electromagnetic (EM) interference shielding materials. Highly effective results have been reported using red mud showing maximum efficiency of 51.4 dB in X-band range, various agricultural waste displaying reflection loss of up to − 87.117 dB (in the range 0.01 to 20 GHz) and miscellaneous waste giving EMI SE of 80 dB in X-band frequency. A separate section is dedicated to emphasizing future work and recommendations.
Graphical abstract
... In the market, there are several types of microwave absorbers such as wedges, pyramidal, flat, and convoluted. Among the varieties that have been long in the market for business purposes are pyramid types [4].The dielectric properties are important in the design of electrical and electronic equipment and suitable techniques for determining the dielectric properties of various materials applications have been developed. The interest of dielectric properties is describing the behavior of material subjected to the microwave frequency. ...
Nowadays, the resources of roofing materials are abundant, which are the essential materials to build houses. It is of great significance to develop the roofing material with absorbing function for shielding electromagnetic radiation. This study is conducted to design a corrugated bamboo roofing microwave absorber that can absorb electromagnetic wave for frequencies 1 to 12 GHz. Three types of roofing bamboo with different designs namely Model A, Model B and Model C has been developed. The size of all types of proposed roofing bamboo is 60 cm width x 60 cm in length. The design is simulated using Computer Simulation Technology (CST) Microwave Studio software. The arch method is used to analyse microwave absorber performance. It contains of a wooden structure in the shape of semi-circular for enabling the proper positioning towards transmitting and receiving the two horn antennas. Bamboo can be used as an absorbent material. The expected result for bamboo roofing microwave absorber is to get a high performance of microwave absorption which is above 20 dB. The third model or Model C has recorded the highest value of an absorption level.
... Biocomposites have environmental advantages such as low density, high specific strength, enhanced energy recovery, CO 2 neutrality after burning, easy processing, bio-degradability and low cost [3][4]. Hence, many studies have been made to realize the prospective of using agricultural waste such as rice husk, kenaf, sugarcane bagasse and pineapple leaf fiber as an alternative material for electromagnetic absorber [5][6][7][8][9]. ...
... Due to this, organic materials such as agricultural wastes have gained a lot of interest among researchers. Different types of microwave absorbers from varied agricultural wastes have been studied such as rice husk [5] , sugar cane baggase [6], corn stove [7], dried banana leave [8], oil palm ash [9] and many others. Most of the absorbers offer good absorption performances that surpass the threshold of -10dB reflection loss. ...
This paper presents the electromagnetic wave (EW) absorption properties in terms of complex permittivity and permeability of novel green composites coconut fiber coir and charcoal powder materials. The samples were fabricated using the raw agricultural waste coconut fiber coir, charcoal powder, epoxy resin and hardener with varied composition. The dielectric properties of the materials were characterized using two-port waveguide measurement method over the X-band frequency (8.2 – 12.4GHz). The average permittivity value measured is approximately 3.00 with 10wt% charcoal has the highest permittivity of 3.59. Apart from that, all samples exhibit good reflection loss of better than -25dB which means more than 99% absorption rate. The result shows the composite material is a promising organic material for electromagnetic absorber applications.
... The others material that used is sugar cane baggase , banana leaves (Farhany, 2012), rubber tire dust (Cheng, 2012), rubber wood sawdust-based (Azizah, 2015), corn stover (Smythe, 2014) absorbing paint (Hasnain, 2012), rice husk-carbon nanotube composites (Lee, 2013, oil palm ash (Noordin, 2012), sugarcane-beach sand based (Panwar, 2014) and others. ...
Green technology wedge microwave absorber is design is done by using the rice husk as the main material. This material effect to reduce the size and effect the environment friendly. Besides that, the shape of microwave absorber is the important parameter that affects the performance of RF absorbers. In this work, different dimension of wedges are discussed to compare the reflection loss or S11 result of wedge microwave absorber. The frequencies range that consider in this works starting at 0.01 GHz to 10 GHz. The design is started with the basic design (Design A) of wedge microwave absorber is contains two wedge with height = 15 cm. For Design B, a wedge microwave absorber with varies dimension of centre absorber height from 6 cm to 14 cm. This microwave absorber is design in CST Microwave Studio using agricultural waste of rice husk with dielectric constant of 2.9.
... Recently, the electromagnetic absorbing materials that show outstanding microwave absorbing properties not only at room temperature but also at high temperature are widely used in commercial and military applications12345678910. Silicon nitride (Si 3 N 4 ) ceramics are well known for not only high-temperature strength, good oxidation, resistance, thermal–chemical corrosion resistance, thermal shock resistance and low thermal expansion coefficient in the field of thermal structure materials, but also its excellent electrical insulation properties, low dielectric constant and loss tangent in the field of microwave transmission materials1112. ...
C f –Si 3 N 4 sandwich composites were prepared by gelcasting using α-Si 3 N 4 powder, SiC-coated carbon fibers and sintering additives as starting materials. The microstructure and composition, dielectric properties of C f –Si 3 N 4 sandwich composites were investigated. SEM and EDS analysis results reveal that the SiC interphase could effectively overcome incompatibility between carbon fiber and silicon nitride matrix under the condition of pressure-less sintering at 1700 1C. The investigation of microwave absorbing property reveals that, compared with the Si 3 N 4 ceramics, both the real (ε') and imaginary (ε'') permittivity of C f –Si 3 N 4 sandwich composites show strong frequency dispersion characteristics at X-band. Microwave absorption ability of the C f –Si 3 N 4 sandwich composites are significantly enhanced compared with pure Si 3 N 4 ceramic, and the reflection loss gradually decreases from À3.5 dB to À 14.4 dB with the increase of frequency, while the pure Si 3 N 4 ceramic keeps at À0.1 dB. Particularly, the relationship between permittivity of C f –Si 3 N 4 sandwich composites and frequency at X-band has been established through an equivalent RC circuit model. Results showed that both ε' and ωε'' are inversely proportional to the frequency square ω 2 , and the predicted results agree quite well with the measured data.
... With the development of high-tech surveillance and precision guidance technologies, the demand of stealth ability in weapons has reached a higher level [1][2][3], especially in air weaponry operated on high temperature [4][5][6][7][8][9][10][11][12]. Ceramic matrix composite is one of the most advantageous high-temperature stealth materials presently studied due to their desirable properties of high specific strength and specific modulus, as well as resistance to erosion and oxidation. ...
Gelcasting was employed to fabricate Si3N4/SiC whisker (SiCw) composite ceramics, and the effects of heat-treatment temperature on the length-to-diameter ratio of the whiskers and SiCw content on microwave dielectric properties were studied. Compared with pure SiCw of spherical structure obtained at temperature of 1,750 °C(Ar), pure SiCw treated at 1,600 °C(Ar) showed rod-like structure, higher dielectric properties and more evenly distribution in Si3N4/SiCw composite ceramics. Both the real (ε′) and imaginary (ε″) permittivity of Si3N4/SiC whisker (SiCw) composite ceramics decreased with increasing frequency and increased as the whisker content raised owing to the interface and SiCw playing a role of dipole in the frequency range of 8.2–12.4 GHz. In addition, comparing the ceramics with lower content of SiCw, the reflectivity of the composite ceramics moved to a lower frequency; the maximum absorption peak reached −22.4 dB at the whisker content of 15 wt%.
... The two most popular microwave absorbers that are currently on the market are Eccosorb's VHP-8-NRL absorber [17] and TDK ICT-030 absorber [18]. The following are references to others who have conducted research on microwave absorbers: Hasnain et al. [19], Salleh et al. [20], Yusof et al. [21], Farhany et al. [22], Noordin et al. [23], Nornikman et al. [24], Malek et al. [25], and Ibrahim et al. [26]. ...
The need to find ways to effectively utilize the large quantities of agricultural waste that are produced is indicative of the huge potential associated with producing an alternative pyramidal microwave absorber for anechoic chamber-testing applications. We propose the development of a pyramidal microwave absorber that can use sugar cane bagasse (SCB), a byproduct from the production and processing of sugar cane, as the absorbent. In this paper, we report the results of our use of dielectric probe measurement to determine the dielectric constant and loss tangent of SCB. These values were used to model and simulate an SCB pyramidal microwave absorber in Computer Simulation Technology's (CST's) Microwave Studio. This absorber was operated in the microwave frequency range between 0.1 GHz and 20.0 GHz.
Agriculture waste has huge potential to be used as an alternative material for constructing microwave absorber which is typically used in an anechoic chamber. The existing microwave absorbers are normally manufactured from chemical substances. This project is proposing the use of a new composite biomass material namely coconut coir, for constructing microwave absorbers. Generally, pyramidal shape is chosen since it is commonly used in the industry. The major part of this project involves an intense study in designing and developing the best techniques to construct pyramidal shape microwave absorber. The frequency range investigated in this work is between 1GHz to 12GHz. Referring to the commercial absorber as the standard, the reflectivity performance of this coconut coir pyramidal absorber was thoroughly investigated in this research. It is then proven that the biomass material used in this study is found to have a significant impact on the microwave absorber performance.
Nowadays, most people rely on the electronic devices for work, communicating with friends and family, school and personal enjoyment. As a result, more new equipment or devices operates in higher frequency were rapidly developed to accommodate the consumers need. However, the demand of using wireless technology and higher frequency in new devices also brings the need to shield the unwanted electromagnetic signals from those devices for both proper operation and human health concerns. This paper highlights the potential of nanocellulose for electromagnetic shielding using the organic environmental nanocellulose composite materials. In addition, the theory of electromagnetic shielding and recent development of green and organic material in electromagnetic shielding application has also been reviewed in this paper. The use of the natural fibers which is nanocelllose instead of traditional reinforcement materials provides several advantages including the natural fibers are renewable, abundant and low cost. Furthermore, added with other advantages such as lightweight and high electromagnetic shielding ability, nanocellulose has a great potential as an alternative material for electromagnetic shielding application.
This paper presents the performance effect of hollow pyramidal microwave absorber that had been applied with slotted array principle. The Sierpinski triangle was used as the slotted on the hollow pyramidal microwave absorber. This paper includes the theories, simulation and measurement result. The simulation using CST Microwave Studio Suite used to predict the Sierpinski triangle design of microwave absorber performance. Measurement had been done successfully via an arch method at 8 GHz till 12 GHz. From the increasing iteration in Sierpinski triangle principle leads to stable the impedance of absorber and resulting high absorption at frequency range between 11 GHz till 12 GHz.
This paper investigates the performance of multilayer pyramidal hollow green biomass coated absorbing materials. The designed absorber is simulated using CST Microwave Studio. Several experimental evaluations have been executed to investigate the performance of the tested absorber using free space arch measurement method. The frequency between 8 and 12 GHz was selected for performance evaluation. The results show that, the multilayer pyramidal shaped of microwave absorber produces excellent performance results.
An anechoic chamber is considered good when there is no signal reflection inside the chamber and also when there is no incoming signal from outside the chamber. The key element inside an anechoic chamber is the absorbing material. The evaluations of mini anechoic chamber fitted with coated absorbers were carried out by analyzing the absorption performance. The study includes the comparison of measurement with and without coated absorbers. The evaluations were carried out using 500 MHz, 2 GHz and 10GHz frequencies. The most significant result shows an absorption level of up to approximately 75% when the chamber was fitted with coated absorbers for 10 GHz.
C-f-Si3N4 sandwich composites were prepared by gelcasting using alpha-Si3N4 powder, SiC-coated carbon fibers and sintering additives as starting materials. The microstructure and composition, dielectric properties of C-f-Si3N4 sandwich composites were investigated. SEM and EDS analysis results reveal that the SiC interphase could effectively overcome incompatibility between carbon fiber and silicon nitride matrix under the condition of pressure-less sintering at 1700 degrees C. The investigation of microwave absorbing property reveals that, compared with the Si3N4 ceramics, both the real (epsilon') and imaginary (epsilon") permittivity of C-f-Si3N4 sandwich composites show strong frequency dispersion characteristics at X-band. Microwave absorption ability of the C-f-Si3N4 sandwich composites are significantly enhanced compared with pure Si3N4 ceramic, and the reflection loss gradually decreases from -3.5 dB to -14.4 dB with the increase of frequency, while the pure Si3N4 ceramic keeps at -0.1 dB. Particularly, the relationship between permittivity of C-f-Si3N4 sandwich composites and frequency at X-band has been established through an equivalent RC circuit model. Results showed that both epsilon' and omega epsilon" are inversely proportional to the frequency square omega(2), and the predicted results agree quite well with the measured data.
Palm oil mill in Malaysia own by various organization and body. The size and capacity of the mill are also different from each other. The capacity of the mill and production rate may affect the quality of the POFA. Hence, the different in quality of palm oil fuel ash (POFA) may occur. So, the properties of POFA concrete produced from each mill maybe different compare to the other. In order to determine the quality of POFA from different mills, an experiment with two types of concrete, which are OPC concrete (25Mpa), and POFA concrete with 20% replacement of POFA from the eight mills was conducted. The test comprise of compressive strength 7days, 28days and 60days and the workability of concrete at fresh state. The chemical composition for all eight mills POFA will be determined. It was found that the POFA from different mills were different in chemical composition and undergoes of production of POFA. Therefore the slump and compressive strength of POFA concrete also different from each other. POFA from Pekan mill contain highest silica contain compare to other.
The purpose of this work is to determine the absorption effect by using carbon as absorbing material. It will be used in anechoic chamber in order to avoid reflections that occur on the wall of the chamber. From polystyrene, the absorbers are cut into pyramidal shaped. The pyramidal shaped is chosen because it could meet the specified industrial standards which can work well at wide range of microwave frequency. To verify the performance of the absorber, a measurement is conducted to determine the absorption rate in frequency range 1 to 10 GHz. The absorber also compared to commercial absorber. The results shows carbon is a good material to absorb the microwave energy. The absorber that has been developed is a low cost with reliable performance.
Agricultural waste bears huge potential to be applied as an alternative and bene-ficial invention for various applications. One of the identified is as an effective microwave signal absorbers for anechoic chamber. In this work, a type of agricultural waste, which is the rice husk, a by-product of paddy, is used in the design of a pyramidal microwave absorber which will be able to operate effectively in the microwave frequencies, from 1 GHz to 20 GHz. In order to test its feasibility, the best type of bonding resin must first be identified. Two types of resin, Urea Formaldehyde (UF) and Phenol Formaldehyde (PF) are mixed with the rice husk in order to investigate the dielectric property resulting from this blending process. Both materials are compared using three different percentage of binder content, which are 10%, 20% and 30%. Free Space Measurement Method is chosen to measure the dielectric constant of the different blends of rice husk. These microwave absorber are also simulated in CST Microwave Studio using the values that are obtained from the Free Space Measurement Method, in order to determine and compare the reflectivity performance in terms of S 11 result. Observation of the results showed that different blends will give the different dielectric constant, and as a result, a different mi-crowave absorber reflectivity. It also proved that with increasing binder percentage, reflectivity of the pyramidal microwave absorber is also improved. Thus, an alternative material, which is also used to be a less useful agricultural waste, is also proven potentially suitable for application as a microwave absorber.
Anechoic chambers signal absorption capability is directly correlated to its performance. One of the main components in enabling signal absorption is the design and material used in designing the absorbers. Two of the main types are pyramidal and wedge-shaped ones. In this work, truncated pyramidal and truncated wedge absorbers for anechoic chamber application have been designed to operate effectively in the microwave frequencies from 1 - 10 GHz. The absorbers were simulated using a fusion of carbon-based material with different features and coating thickness to improve their performance and significant material cost savings. Material consideration for the basic pyramidal and wedge structure has also been taken into account. The designs are simulated using CST Microwave Studio. Simulated results showed that the coating of half the absorber height produced the best performance in terms of signal absorption.
A method for reducing palm shell residues has been investigated. Using pyrolysis technique, the residues are transformed into carbons, which are later used as a lossy elements in microwave absorber application. The microwave properties of permittivity,( e), loss tangent, (tan d) and absorption performance of microwave absorber utilizing palm shell carbon mixed with unsaturated polyester resin were studied in the microwave region of 8 to 12 GHz (X-band). The measurement of ( e) and (tan d) emphasize on the influence of carbon concentration (mass %) and pyrolysis temperature in the production of the carbon. It was found out that by increasing carbon pyrolysis temperature, an increase in ( e) and (tan d) had been observed. The increase of carbon concentration inside each measured sample also influenced the increase of ( e) and (tan d) condition. The optimum (tan d) was found by using 30% carbon pyrolysed at 800oC temperature, suggesting significant contribution in dielectric loss properties of the material. The preparation of microwave absorber by utilizing 30% mass concentration of palm shell carbon mixed with unsaturated polyester resin had been tested for microwave absorption. The amplitude of the absorption was relatively measured to a metal plate reference, which resulted in a various microwave absorption with respect to the thickness of the absorber. Moderate microwave absorption around - 10 dB was achieved for most samples within the same frequency band, with maximum absorption of - 30 dB for a thickness up to 75 mm. All the data indicates the possibility of using pyrolysed carbon derived from palm shell residues in providing an affordable solution for microwave technology as well as an alternative in managing the increase of the residues throughout the country
A composite electromagnetic absorber for anechoic chambers is proposed with the structure consisting of a pyramidal foam and a lossy frequency selective surface (FSS) structure. Simulation results show that the period of absorber array and the pyramid base impact directly on absorption nulls, and the effects of pattern size, surface impedance and substrate thickness of FSS are more complicated due to interactions between the pyramidal foam and FSS structure. Two examples are discussed and the results show that improved absorption below 3GHz can be achieved by properly selecting parameters. © 2013 Antenna Society of the Chinese Institute of Electronics.
Abstract—In the military applications, electro-optics and electro- magnetics features of the cloths made of special textile structures and certain fibers play an important role in producing textile characterized with high ability of camouflage. This means,not allowing enemy to precisely determine the moving and mute targets using available radar or any other electro-optics sensors. The aim of this paper is to determine the effect of the composite fabrics structure parameters on the fabrication of a resistive sheet used in many radar applications. The objective sheet can be used as a lossy sheet in absorbing mechanism. The radar absorbing mechanism,has been studied with emphasis on the single layer structure mechanism,with a resistive sheet. Fabric structure of the resistive sheet was accurately chosen and coated 220,Hebeish et al. with lossy material. For coating, several formulas of fabrics using carbon black were tested to determine the best chemical treatment in accordance with their functional performance. Lab measurements have
Abstract—A proper model of RF absorber must be developed based on information such as absorber reflectivity, in magnitude and phase, for various angles of incidence, and for parallel and perpendicular polarizations. Unfortunately, these data are not available due to the practical limitations of the test fixtures to measure the RF absorber performance. Manufacturer data sheets normally specify only the magnitude of the absorber reflectivity for normal incidence. A model has been developed in this paper for pyramidal RF absorber with pyramid length shorter than a quarter wavelength and poor reflectivity performance. Since the reflection from the metal backing would be much higher than the reflection and scattering from the pyramid tips, the metal boundary may be modeled as a lossy dielectric with certain effective dielectric constant, εef f, and effective conductivity, σeff, and the thickness extends to infinity. The appropriate values of εeff and σeff can be derived based on the reflectivity information given by the manufacturer’s data sheet. The reflectivity at oblique incidence is calculated and compared with the results of method of homogenization and moment,method. A reasonable match between the different models is obtained. The plane-boundary dielectric model can be used to evaluate the degradation of reflectivity level with respect to angle of incidence. It can be used in a simulation tool for design of anechoic chamber.
The physical models of single- or double-layer microwave absorbers containing left-handed materials as well as their corresponding design principles and methods are proposed. The theoretically derived calculation formulae that may be used in the design procedures are also presented. Finally, a design example is given. The results obtained may be useful to the researchers and designers working in the area of microwave absorber theory, technology and engineering.
The most common and simple structure to reduce the level of the
reflected power from a metallic surface is the single layer structure
known as Salisbury screen which is a sheet of porous material
impregnated with graphite and spaced a quarter-wavelength off a metallic
backing plate. The main disadvantage of this mechanism is the narrow
frequency bandwidth. Many techniques have been reported to improve the
working frequency bandwidth but with some degradation in the other
technical properties of the overall structure. In this paper a novel
technique has been introduced based on a spatial kind of material called
the circuit analog screen. Theoretical analysis shows that the bandwidth
of the reflected power will be improved if the graphite sheet of the
Salisbury screen has been loaded by circuit analog screen with spatial
geometry with spatial parameters
The reflectivity of a pyramidal absorber is analyzed accurately by using the spatial network method. As a practical modeling of the pyramidal absorber, a novel modeling technique based on a synthesized capacitance model is proposed to analyze its reflectivity. The validity of the proposed model is confirmed through the comparison with results given by the accurate analysis for the normal incidence and through the comparison with experimental results. The proposed model can be applied to calculate the reflectivity of pyramidal absorber for the oblique incidence as well as for the normal incidence of electromagnetic wave
The absorber used in anechoic and semi-anechoic chambers employed
for emissions and immunity testing of digital devices is examined. Using
reflectivities obtained by the method of homogenization, the advantages
and disadvantages of urethane pyramids, twisted-pyramids, wedges, as
well as ferrite tiles, ferrite grids, and “hybrid”
combinations of urethanes and ferrites, are determined. General
reflectivity guidelines are also presented for comparing absorber used
for the electromagnetic compatibility (EMC) testing of digital devices
from 30 to 1000 MHz
Electromagnetic scattering from pyramidal and wedge absorbers used
to line the walls of modern anechoic chambers is measured and compared
with theoretically predicted values. The theoretical performance for
various angles of incidence is studied. It is shown that a pyramidal
absorber scatters electromagnetic energy more as a random rough surface
does. The apparent reflection coefficient from an absorber wall
illuminated by a plane wave can be much less than the normal absorber
specifications quoted by the manufacturer. For angles near grazing
incidence, pyramidal absorbers give a large backscattered field from the
pyramid side-faces or edges. The wedge absorber was found to give small
backscattered fields for nuclear-grazing incidence. Based on this study,
some new guidelines for the design of anechoic chambers are advocated
because the specular scattering models used at present do not appear
valid for pyramids that are large compared to the wavelength
Wedge absorber design and simulation for mice step IV
- C T Rogers
- L Coney
- G Hanson
C. T. Rogers, L. Coney, G. Hanson, " Wedge Absorber Design and Simulation for Mice Step IV ", COOL 2009.
Eric Weisstein's World of Science
- Eric W Weisstein
Eric W. Weisstein, Eric Weisstein's World of Science, 2008 http://scienceworld. wolfram. com /physics/