Farid Zubir

Design, implementation and performance of ultra-wideband textile antenna

Communication technology is increasingly pervading everyday life. The rapid progress in wireless communication besides the increasing interest in wearable antennas and electronics in civil, medical, sport wear and military domains promises to replace wired- communication networks in the near future in which antennas are in more important role. Recently, there has been growing interest in the antenna community to merge between wearable systems technology, Ultra-Wideband (UWB) technology and textile technology. All these together have resulted in demand for ∞exible fabric antennas, which can be easily attached to a piece of clothing. In this paper, three difierent structures of UWB antennas using clothing materials and suitable for wearable application were fabricated and presented. The substrate of the designed antennas was made from jeans textile material, while radiating element and ground plane are made out of copper tape. The operating frequency of all three designs is between 3GHz and 12GHz. Measured results are compared with simulations and good agreement was observed.

Log Periodic Fractal Koch Antenna for UHF Band Applications

In this paper, the design of Log Periodic Fractal Koch Antennas (LPFKA) is proposed for Ultra High Frequency (UHF) band applications. The procedure to design the LPFKA with three different numbers of iterations in order to reduce the antenna size is discussed. The Computer Simulation Technology (CST) software has been used to analyze the performances of the designed antennas such as return loss, radiation patterns, current distribution and gain. The antennas have been fabricated using FR4 laminate board with wet etching technique. Using fractal Koch technique, the size of the antenna can be reduced up to 27% when the series iteration is applied to the antennas without degrading the overall performances. Both simulated and measured results are compared, analyzed and presented in this paper.

Design and Analysis of Microstrip Reflectarray Antenna with Minkowski Shape Radiating Element

This paper describes the design and analysis of a Microstrip Re∞ectarray Antenna (MRA) with Minkowski shape radiating element at frequency of 11GHz. This structure has been analyzed and compared with the traditional re∞ectarray element (square element patch). It is found that this antenna array has lower sidelobe level (SLL) characteristic which is down to i25dB. This MRA has maximum realized gain of 29.6dB with half-power beamwidth (HPBW) of 3.7 - . The validation for the proposed MRA is done by comparing the simulated and measured E-plane radiation pattern. A very good agreement is found from the comparison between simulation and measurement.

Triple-band printed dipole antenna with single-band AMC-HIS

In this paper, the designed of triple-band printed dipole antennas are incorporated with single-band artiflcial magnetic conductor (AMC). The single-band AMCs are designed to resonate at 0.92GHz, 2.45GHz and 5.8GHz using TLC-32 dielectric substrate. The four important parameters in AMC high impedance surface (HIS) design are also described in this paper. By simulating a unit cell of the AMC structure using a transient solver in Computer Simulation Technology (CST) software, the characteristic of the AMC can be characterized. The AMC condition is characterized by the frequency or frequencies where the magnitude of the re∞ection coe-cient is +1 and its phase is 0 - . It has high surface impedance (Zs) and it re∞ects the external electromagnetic waves without the phase reversal. This characteristic of AMC enables the printed dipole to work properly when the antenna with AMC ground plane (GP) is directly attached to the metal object. The performances of the antenna with and without AMC structure as a ground plane to the antenna such as return loss, realized gain, radiation e-ciency, radiation pattern and directivity are studied. Reported results show that the performances of the antenna are improved. Hence, the designed dipole tag antenna can be used for metal object identiflcations when the AMC structure is introduced as a ground to the antenna. The properties of the antenna are also remained well when the size of metal plate attached to them is increased.

Simulated fractals shape for unit cell reflectarray

In this paper, simulation results of an identical unit cell with different shape of printed radiating element have been briefly discussed. Since the most severe problem in reflectarrays is narrow bandwidth, there are much efforts have been done in recent years to overcome this limitation. There are two factors that causing a narrow bandwidth of the reflectarrays which are the narrow band of the radiating elements and the differential spatial phase delay between elements on the reflectarray itself. Therefore, the main purpose of this paper is to investigate the suitable shapes of element for a better reflectarray cells development. The suitable shape means it has wider linear phase range and better gradient in degree per micrometer (°/µm) which means the smaller value of gradient, so that when the frequency changes, the phase distribution only varies in a constant which is a little bit in degree (°) for the whole reflectarray structure. From the observation, minkowski element patch has wider linear phase range and koch-triangle element shape has better in gradient which is not quite sensitive in patch variation around its resonance region.

Electromagnetic Band Gap Structure for Planar Ultra Wide Band Antenna

An innovative technique involving the usage of a mushroom Electromagnetic Band Gap (mEBG) structure with an ultra wideband (UWB) antenna is reported in this work. A single unit of mEBG lattice is incorporated within a novel UWB antenna to perform the band rejection operation. The antenna can be fixed to reject or reduce the transmit power for any band within the UWB spectrums of frequencies through a careful design of this mEBG structure, thus solving the problems concerning interference and reducing the requirements for complex filtering electronics within the UWB devices.

Microstrip antenna array's gain enhancement via Electromagnetic Band Gap structures

For a point-to-point communication system, an antenna array with high gain is essential and in this work, by incorporating electromagnetic band gap (EBG) structures at a specific location within the antennas peripherals, the gain of the antenna could be enhanced further. The EBG structures reduced mutual couplings between the adjacent patches thus make them radiates effectively. On the other hand, the EBG structures located at the edge of the antenna suppressed surface waves and prevent it from propagating to the edges, thus reduced the side and back lobes. This further enhances the front radiation characteristics of the antenna and also increased the gain. The techniques and guidelines on how to achieve the objectives is presented and the simulated and measured results complement each other.

Long-Range Monitoring System with PDMS Material

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.

Highly Efficient Power Amplifier for Microwave Transmitter

Sustainability is currently becoming a trend in technologies such as telecommunications. The goal is to reduce power consumption and increase the battery life of mobile nodes. The highest power consumer in the telecommunication module, the power amplifiers were designed using inefficient configurations as the older emphasize is only to achieve highest linearity possible at the output. This work proposes designs for Class E power amplifiers operating at 2.4 GHz based on nonlinear SPICE FET models using two different Sokal’s empirical equations. One emphasizes considerations of output power with quality factor, the other does not. Clear differences can be observed through simulation results as the newer Sokal’s equation proved to be more efficient. This analytical solution can be used to design future power amplifiers where efficiency is the prime concern.

The effects of straight-pin type earring worn on the head on SAR at 2.4 GHz and 5.8 GHz

This paper presents the effect of metallic items on the antenna performance and SAR at 2.4 GHz and 5.8 GHz. The simulations were performed by means of CST Microwave Studio. The patch antenna was used as the radiating source while the metallic items were modeled as λ/4 and λ/2 straight pin-type earrings respectively. The results have shown that the head has shifted the antenna resonant frequencies at both frequencies investigated. This study has also indicated that the additional metallic item in close proximity to the head has an additional effect on antenna resonance, albeit quite a small one. However, the straight-pin type earrings have significantly increases the amount of energy absorbed in the human head at both frequencies tested.