Maisarah Abu

Design synthesis of 5.8 GHz octagonal AMC on a very thin substrate

This paper proposed a development of 5.8 GHz Artificial Magnetic Conductor, AMC using very thin substrate with thickness of 0.13 mm. Different shapes of PEC metallization are discussed in order to achieve the highest bandwidth of unit cell AMC. Another approaches for increasing the bandwidth is by applying the ring patch around the substrate as well as implementing the DGS ground plane. The proposed design produces 1.96 % bandwdith of unit cell. Applying the 2 x 4 unit cell arrangement gives the best result for directivity equal to 6.75 dBi, gain of 6.83 dB, efficiency = 98.41 % and return loss = -45.63 dB.

2.45 GHz RFID reader array antenna with hexagonal geometry arrangement

In this paper, 2.45 GHz Radio Frequency Identification (RFID) reader antenna with hexagonal geometry is proposed to obtain a high gain directional pattern. The mittering technique is used at each junction of the transmission line to reduce the power loss. The parametric study is conducted to get the best dimension and position of all six elements of truncated patch antenna to operate at 2.45 GHz. The simulation and measurement readings of the antenna are compared. In conclusion, the performance of the designed antenna improves the referenced antenna in terms of gain and size. The measured gain is 9.0 dBi and the size of the designed antenna is about 37% smaller than the referenced antenna.

A 2.45 GHz Harmonic Suppression Rectangular Patch Antenna with Circular Polarization for Wireless Power Transfer Application

ABSTRACT This paper presents a 2.45 GHz harmonic suppression rectangular patch antenna with circularly polarized for wireless power transfer applications. The miniaturized proximity-coupled antenna has the advantage of excellent higher harmonic suppression of up to −3 dB at harmonic frequency. This characteristic is achieved by introducing a U-slot and the symmetrical arm of inverted U-stub embedded on the transmission feed line. The overall size of the proposed antenna gives 36% reduction of substrate area as compared to conventional designs. The antenna is designed, optimized, and simulated on FR-4 substrate of dielectric constant 4.3, loss tangent 0.019, and height 1.6 mm offering moderate gain and good axial ratio of 1.48 dB. Details of the simulated and experimental characteristics of the antenna are presented and discussed.

Magnetic and Microwave Absorption Properties of Magnetite-Durian Shell Nanocomposite Sheet in Gigahertz Range

In this paper, a novel microwave absorber of thin, light weight, flexible, green and low cost magnetic nanocomposite sheet that can work in high frequency range is fabricated. The vast and increasing numbers in electronic and telecommunication devices has create electromagnetic interference (EMI) in which may lead to application disturbance. Therefore, electromagnetic (EM) wave absorber with the ability of high absorption rate is strongly demanded. Here, durian shell (Durio zibethinus Murray) embedded magnetite (Fe3O4) nanocomposite sheets were prepared via pulping and lumen loading technique. The nanocomposite sheets were fabricated by varying the weight percentage of the filler content (2-10 wt% of Fe3O4) at constant thickness and varying the thickness of the sheets (0.1-1.0 mm) at constant filler content. FESEM micrograph shows that the Fe3O4 nanoparticles are in cubical and spherical shape with the 20–50 nm of size range. The microwave absorption properties of the sheets were tested by a vector network analyze (VNA) in the frequency range of 4-18 GHz. The samples were also tested using vibrating sample magnetometer (VSM) in order to study the magnetic properties. The absorption or maximum reflection loss (RL) of the samples increases continually and the increase of both filler content and sample thickness has led to the shift of dip to lower frequency region.

Ultra Thin Flexible Octagonal Metamaterials Absorber

With the rapid growth of communications via the Internet, the need for an effective firewall system which has not badly affect the overall network performances has been increased. In this paper, a Field Programmable Gate Array (FPGA) -based firewall system with high performance has been implemented using Network FPGA (NetFPGA) with Xilinx Kintex-7 XC7K325T FPGA. Based on NetFPGA reference router project, a NetFPGA-based firewall system was implemented. The hardware module performs rule matching operation using content addressable memory (CAM) for higher speed data processing. To evaluate system performance, throughput, latency, and memory utilization were measured for different cases using different tools, also the number of rules that an incoming packet is subjected to was varied to get more readings using both software and hardware features. The results showed that the designed firewall system provides better performance than traditional firewalls. System throughput was doubled times of the one with Linux-Iptables firewalls.

Analysis on element shape geometries to enhance reflection coefficient and gain of reflectarray antenna

An analysis on element shape geometry is presented in this paper to enhance the reflectarray element bandwidth, to produce a more reliable phase distribution over the reflectarray antenna aperture and to have a good reflection element performance. The shape analysis consists of circular patch element, circular ring element and circular square ring element. The reflection coefficient parameter focuses on phase range, phase slope, bandwidth and return loss performance for each analysis and presented in this paper. It is shown that the proper selection of element shape geometry will significantly affects the reflection coefficient of reflectarray element and the antenna gain performances.

Miniaturized Implantable Ultra-Wideband Antenna with Bio-Compatible Substrate Material

Ultra-wideband (UWB) technology was nowadays increased in interest for various applications due to its distinctive characteristics where it able to carry signals passes through obstacles unlikely narrow-band frequency that tends to reflect the signal. Through this paper, a design of miniaturized implantable UWB antenna utilizing various bio-compatible materials is studied. These materials are to be compared and determined the best material to be used for the design in terms of its return loss, center frequency, bandwidth, antenna gain and total efficiency. The antenna is designed in a structure of circular-ring with slit patch antenna using CPW profile with dimension of 10×10 mm2. As for the materials used in this study are Silicon, PDMS and Teflon PTFE. Each of this substrate has a thickness of 0.5 mm, 2.5 mm, and 1.5 mm correspondingly. After comparing these three materials, the one that gives the best result is Teflon PTFE with return loss at 11.91 GHz and 5.58 GHz bandwidth that covers from 9.16 GHz to 17.74 GHz frequency range. The antenna gives out total gain and efficiency of 2.54 dB and 86.5% respectively.

Bendable Hexagonal Resonator Designs for Chipless Tag

This paper presented a new design of bendable hexagonal resonator for chipless RFID tag. A linearly polarized plane wave and Radar Cross Section (RCS) probes were used in simulation set-up. The optimized resonator was fabricated on a thin fast-film substrate with dielectric constant, εr=2.7 and substrate thickness, t = 0.13 mm. The fabricated resonator consisted of 3 hexagonal slots which represented three bit 1s. The measurement was performed to validate the designed resonator. It was measured using two transmitting and receiving horn antennas along with the network analyzer. The measured magnitudes were-24.292 dB, -28.854 dB and-32.234 dB.

A Facile Coating Method for Superhydrophobic Magnetic Composite Sheet from Biodegradable Durian Peel for Electromagnetic Wave Absorbance Application

Most of the electromagnetic (EM) wave absorbers are commonly made from polymer-based materials. A large number of polymers are resistant to the environmental degradation and are thus responsible for the buildup of polymeric solid waste materials. These solid wastes cause acute environmental problems and remain undegraded for quite a long time. In a view of the awareness and concern for the problems created by the polymeric solid wastes, new biodegradable cellulosic composite with low cost and nontoxic materials, have been designed and developed. However, the properties of natural fibers that tends to absorb water, thus limiting their application. In this study, precipitated calcium carbonate (PCC) was added with stearic acid (SA) in order to generate a hydrophobic coating formulation. PCC works as filler and SA acts as surface hydrophobic modification agent. Polymer latex was then added to the coating compound as the binder. The composite surface morphology was inspected using scanning electron microscope (SEM). Results show that durian peel composite sheet had successfully achieved a superhydrophobic surface with a water contact angle of 154.85° which exceed 150°.

Stacked patch antenna harmonic suppression at 2.45 GHz for wireless power transfer

This paper presents antenna harmonic suppression for wireless power transfer systems. It is demonstrated that application of open stub on the feed line, curvature slots and notch at the antenna patch suppressed undesired signals exhibit near second order effectively. The partially ground with a circular slot at ground plane is introduced to minimize the overall patch size. The patch antenna is designed on an FR-4 substrate with εr = 4.7 and 1.6 mm of its thickness. The proposed designs yield -29.536 dB return loss at fundamental modes and suppress all the harmonics until the acceptable range up to -3 dB. The proposed antenna, enhanced the bandwidth about three times and offer moderate gain 4.378 dB and gives advantage whereby the patch antenna can work as radiating and filtering of RF signals in a single module without using a filter circuit which contribute additional insertion loss to the systems.