H. Nornikman

Free space measurement technique on dielectric properties of agricultural residues at microwave frequencies

Principles to determine dielectric properties measurement using microwave free-space transmission measurements technique is presented in this paper. The projects main objective was to measure the dielectric properties of different agricultural waste material at microwave frequencies, which in turn, can serve as a potential alternative, replacing conventional printed circuit board (PCB) using FR4 material. A system, which includes a PNA vector network analyzer, horn antennas, and Agilent Technologies 85071E material measurement software were used and described in detail. Techniques and procedures essential in obtaining reliable permittivity data for agricultural waste products were also discussed. The waste products - rice husk, rice straw, and kenaf were studied in the frequency range of 2.2 to 3.3 GHz. These agricultural waste materials were mixed with two distinct resins, namely, Urea Formaldehyde (UF) and Phenol Formaldehyde (PF). Each type of resin was also investigated using different percentage of resin moisture content, and the results were analyzed thoroughly.

Study and Simulation of an Edge Couple Split Ring Resonator (Ec-SRR) on Truncated Pyramidal Microwave Absorber

Split ring resonator (SRR) structure can potentially be incorporated onto the truncated pyramidal microwave absorber. This study considers three difierent patterns of edge couple split ring resonator (EC-SRR) designs. Each EC-SRR design is then placed onto the truncated pyramidal microwave absorber. Outer split gap dimension widths of the EC-SRR are varied, and the various S21 performances are compared. This EC-SRR truncated pyramidal microwave absorber is simulated using CST Microwave Studio simulation software. The study and simulation are performed in low frequency range (0.01GHz to 1GHz) as well as in microwave frequencies range (1GHz to 20GHz). Simulation results of this EC- SRR show improvement of re∞ection loss and S11 performance in the high frequency range of the pyramidal truncated microwave absorber.

RUBBER TIRE DUST-RICE HUSK PYRAMIDAL MICROWAVE ABSORBER

Rubber tire dust-rice husk is an innovation in improving the design of pyramidal microwave absorbers to be used in radio frequency (RF) anechoic chambers. An RF anechoic chamber is a shielded room covered with absorbers to eliminate unwanted re∞ection signals. To design the pyramidal microwave absorber, rice husk will be added to rubber tire dust since the study shows that both have high percentages of carbon. This innovative material combination will be investigated to determine the best re∞ectivity or re∞ection loss performance of pyramidal microwave absorbers. Carbon is the most important element that must be in the absorber in order to help the absorption of unwanted microwave signals. In the commercial

Setup and results of pyramidal microwave absorbers using rice husks

Agricultural wastes are considered not useful and are commonly dumped or burned after crop harvesting. Rice husks from paddy (Oryza sativa) are example of agricultural wastes. Rice husks have been investigated as the material for the pyramidal microwave absorbers. The setup for the fabrication and measurement of the rice husks pyramidal microwave absorbers are discussed. An 8£8 array of pyramidal microwave absorber using the rice husks-polyester-MEKP mixture has been designed and fabricated. There are four main stages in this work: the collection of the raw rice husks materials, the mould fabrication, the pyramidal microwave absorber fabrication and the experiments performed to determine the re∞ection loss performance of the rice husks pyramidal microwave absorbers. Experimental

Performance Simulation of Pyramidal and Wedge Microwave Absorbers

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.

Development Of Pyramidal Microwave Absorber Using Sugar Cane Bagasse (SCB)

The need to flnd ways to efiectively 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 Technologys (CSTs) Microwave Studio. This absorber was operated in the microwave frequency range between 0.1GHz and 20.0GHz.

THE USE OF DIELECTRIC MIXTURE EQUATIONS TO ANALYZE THE DIELECTRIC PROPERTIES OF A MIXTURE OF RUBBER TIRE DUST AND RICE HUSKS IN A MICROWAVE ABSORBER

A change in the relative proportions of a mixture of rubber tire dust and rice husks will cause a change in the mixtures electrical permittivity and its ability to absorb electromagnetic energy. An open- ended coaxial probe was used in conjunction with three dielectric mixture equations (the Kraszewski equation, the Landau equation and the Lichtenecker equation) to obtain the dielectric properties of a mixture of rubber tire dust and rice husks (RTDRH) over the frequency range of 7GHz to 13GHz. Lichteneckers equation for dielectrics proved to be a useful practical formulation for determining the efiective permittivity of homogeneous dielectric mixtures. The efiectiveness of these dielectric mixture equations in determining the efiective permittivity of RTDRH was investigated in this study. A newly developed mixture equation was derived based on these dielectric

Effect on source signal condition for pyramidal microwave absorber performance

In designing a microwave absorber for anechoic chamber, there are many condition can affect the performance of microwave absorber. In this work, four conditions are discussed to compare the reflectivity or S11 of the pyramidal microwave absorber. The conditions are different signal source position, areas, angle, and lastly the distance between signal source and pyramidal microwave absorber. These pyramidal microwave absorber are simulated in CST Microwave Studio by using the rice husk as it based material that have dielectric constant, εr = 2.9. This absorber has been designed to operate effectively in frequency range of 1 GHz to 20 GHz

Reflection loss performance of hexagonal base pyramid microwave absorber using different agricultural waste material

Hexagonal base pyramid microwave absorber is the new design of microwave absorber. In this work, two sub-shapes are considered to compare it reflection loss performance. The shapes are hexagonal and truncated hexagonal base pyramid. Three sample of agricultural waste are used that is rice husk, rice straw and banana leaves. Before that, free space measurement technique is applied to define the dielectric constant and tangent loss of the material used. These microwave absorbers have been designed to operate effectively between the frequencies of 1 GHz and 20 GHz.

Printed omnidirectional antenna for RFID applications

This paper proposed the dual band printed omnidirectional antenna for RFID applications at 2.45GHz. This antenna is made up from the double U-stubs and meander collinear structure. The antenna is based on the microstrip type of antenna. The return loss of the proposed antenna at 2.45GHz is -10.61dB and the bandwidth is 122MHz. The gain that has been achieved for this proposed antenna is 3.798dB.