Fauziahanim Che Seman

4-port Butler matrix for switched multibeam antenna array

This paper introduced the 4/spl times/4 Butler matrix as the beamforming network combined with 4 linear antenna arrays to produce four narrow steerable beams. The designed was aimed for resonance frequency 900 MHz in application of GSM base station transmitter. The position of radiation patterns achieved by this project then compared with the theoretical calculation and simulation using the PCAAD simulation. The resultants of signal strength by four beams were indicated low level that may caused by loss factor to the components used.

Double Square Loop Frequency Selective Surface (FSS) for GSM Shielding

This paper proposes the deployment of Frequency Selective Surface (FSS) in any close building that aims to block the signals from the mobile phones without disrupting other types of communication. The proposed FSS is designed as a band-stop filter to attenuate the Global System for Mobile Communications (GSM) frequency bands operating at 900 and 1,800 MHz. The structure consists of a periodic array of double square loop elements etched on FR-4 substrate. The FSS shows a stable frequency response for the angles of incidence ranging from 0–60° with an attenuation of at least 16.7 dB. The measured results are shown to be in a very good agreement with the simulated results.

Investigations on fractal square loop FSS at oblique incidence for GSM applications

This paper proposes a fractal square loop frequency selective surface (FSS) with dual-band stop behavior. The FSS elements are etched on FR-4 substrate to attenuate signals at GSM900, GSM1800 and IMT2000 frequency bands while transmitting other microwave signals. The unit cell geometry is a modification of the conventional square loop which shows an improvement in stability for oblique incidence up to 45° for both TE and TM polarizations. The proposed FSS shifts the onset of a grating lobe to the outside of the frequency of interest without compromising the target resonant frequencies. The measured results are shown to be in a very good agreement with the simulated results.

Double square loop FSS with slots for closer band spacing at oblique incidence

This paper proposes a modified nested double square loop Frequency Selective Surface (FSS) in order to achieve a higher FSS packing density. By introducing slots to a conventional square loop, a longer electrical length of the FSS and a lower ratio of l/λ can be accomplished. The optimized FSS prototype provides a maximum attenuation of more than 30 dB alongside with 270 MHz and 690 MHz bandwidth for the lower and upper resonant frequencies, respectively. Furthermore, the proposed structure also offers a stable frequency response for both TE and TM modes at normal and oblique incidence, up to 45°. The measured and simulated results are shown to be in a very good agreement with each other.

Transmission of Microwave Signal through Metal-Oxide Thin Film of Energy Saving Glass Using Different Shape of Frequency Selective Structure

Metal oxide thin films are widely used for energy saving glass coating. This coating has the ability of blocking the infrared signal while being transparent to other visible part of the spectrum. However, there is one critical disadvantage of this metal oxide coating which it attenuates useful radio frequency and microwave signal such as GSM mobile signal, personal communication, GPS signal through them. These important microwave signals are fall within the range of 800 MHz to 2200 MHz. Frequency selective structure has been applied to solve the attenuation of microwave signal. With the adding of frequency selective structure, it can bring huge improvement of the transmission loss through it. Computer simulation using CST software is used to investigate the transmission loss through the metal oxide coated glass. The frequency selective structure will be etched out from the metallic oxide coated on the glass. Results showed that different shape of the structure will have different peak transmission loss through the glass. When cross dipole and circle shape been simulated using CST software, it can clearly see that the transmission lost and peak frequency had changed drastically. Then, triangle and pentagon shape also have different transmission through it. In addition, conductivity and electrical properties of coated metal oxide thin film is also very important. The transmission through the different ohmic sheet resistance of metal oxide thin film was also investigated. The sheet resistance value was obtained from the reported experimental results. Simulated results showed that full width half maximum, maximum transmission loss and peak frequency loss was very much dependent on the metal oxide sheet resistance. Therefore, the control of the thickness and oxygen content in metal oxide thin film are very much important to optimize the transmission loss through it for energy saving glass applications.

Characterisation of Copper Nanoparticle Ink Printed FSS for Cellular Signals Suppression

This paper proposes a copper nanoparticle ink printed frequency selective surface (FSS) for cellular signals suppression. The FSS pattern is deposited on a polyimide film by using an inkjet printing technique. The printed FSS elements undergo the post-processing called sintering, where the optimum exposure duration and temperature are determined in order to form a conductive path across the metal pattern. Later, the conductivity of the printed FSS structure deposited on polyimide film is observed. The signal suppression ability of the printed FSS is conducted using the Computer Simulation Technology (CST) Microwave Studio software.

Parametric studies of Archimedean spiral antenna for UWB applications

The paper presents the parametric study effects on the performance of two arm Archimedean spiral antenna (ASA) for UWB applications. The effects of inner radius, arm width and arm spacing are investigated in order to obtain an improved gain and axial ratio over the frequency band of 3.1-10.6 GHz. The numerical studies were performed using commercially available CST software. The results revealed that antennas performance is proportional to the increment of the arm width and spacing while inversely proportional to the increment of inner radius.

Optimization of Transmission Lost for Energy Saving Glass with Different Sheet Resistance Values

Recently, energy saving glass is commonly applied in the modern engineered building. This is due to its advantages of keeping the heat inside the building in winter while rejecting the heat when in summer. The typical energy saving glass is made by applying a very thin metallic oxide such as silver oxide or tin oxide on one side of the float glass. But at the same time, it has the disadvantages of attenuates useful microwave frequencies that ranging from 0.8 2.2 GHz. The examples of the microwave frequency at this range are GSM mobile signal, GPS and personal communication. Frequency selective surface (FSS) has been introduced to overcome this drawback of energy saving glass. In this study, the transmission of the microwave signal is observed through the simulation using Computer Simulation Technology Microwave Studio. Bandpass frequency selective surface of cross dipole shape is used for the simulation. In the simulation, conductivity and electrical properties of glass and metal oxide thin film are important. The microwave transmission was evaluated at various sheet resistance of metal oxide thin film. The results show that the minimum transmission lost increased with the ohmic resistance increased. On the other hand, the peak frequency at various sheet resistance shows constant value at around 1.25-1.30 GHz. The full width half maximum of the microwave transmission increases with the sheet resistance value. The results suggest that FSS structured metal oxide thin film with lowest sheet resistance transmits more signal in the range for GSM phone signal.

Compact Meander Line Telemetry Antenna for Implantable Pacemaker Applications

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.

Design and Analysis of Optimum Performance Pacemaker Telemetry Antenna

The demand for health technology is increasing especially in the telemetry applications. These applications generally use implanted antennas to be utilized for data transfer from patients to other reader devices. This procedure can make the health care more efficient since it provides fast diagnosis and treatment to the patient. Therefore, in order to effectively implement an implanted antenna inside the human body, thorough numerical analysis and simulations are required prior to the fabrication of antenna. In this work, an implanted antenna has been proposed to be designed at 402.5MHz within the biomedical frequency band of 402405MHz. By introducing a compact loop antenna for telemetry applications in a Pacemaker, a number of advantages can be achieved for health care such as efficient data information and quick diagnosis. Moreover, in this work an investigation of compact loop antenna with casing in Pacemaker has been carried out by placing the antenna inside the phantom of human body model.