Mohd Fais Mansor

A Miniaturized Antenna with Negative Index Metamaterial Based on Modified SRR and CLS Unit Cell for UWB Microwave Imaging Applications

A miniaturized antenna employing a negative index metamaterial with modified split-ring resonator (SRR) and capacitance-loaded strip (CLS) unit cells is presented for Ultra wideband (UWB) microwave imaging applications. Four left-handed (LH) metamaterial (MTM) unit cells are located along one axis of the antenna as the radiating element. Each left-handed metamaterial unit cell combines a modified split-ring resonator (SRR) with a capacitance-loaded strip (CLS) to obtain a design architecture that simultaneously exhibits both negative permittivity and negative permeability, which ensures a stable negative refractive index to improve the antenna performance for microwave imaging. The antenna structure, with dimension of 16 × 21 × 1.6 mm3, is printed on a low dielectric FR4 material with a slotted ground plane and a microstrip feed. The measured reflection coefficient demonstrates that this antenna attains 114.5% bandwidth covering the frequency band of 3.4–12.5 GHz for a voltage standing wave ratio of less than 2 with a maximum gain of 5.16 dBi at 10.15 GHz. There is a stable harmony between the simulated and measured results that indicate improved nearly omni-directional radiation characteristics within the operational frequency band. The stable surface current distribution, negative refractive index characteristic, considerable gain and radiation properties make this proposed negative index metamaterial antenna optimal for UWB microwave imaging applications.

Feature Extraction Technique using Discrete Wavelet Transform for Image Classification

The purpose of feature extraction technique in image processing is to represent the image in its compact and unique form of single values or matrix vector. Low level feature extraction involves automatic extraction of features from an image without doing any processing method. In this paper, we consider the use of high level feature extraction technique to investigate the characteristic of narrow and broad weed by implementing the 2 dimensional discrete wavelet transform (2D-DWT) as the processing method. Most transformation techniques produce coefficient values with the same size as the original image. Further processing of the coefficient values must be applied to extract the image feature vectors. In this paper, we propose an algorithm to implement feature extraction technique using the 2D-DWT and the extracted coefficients are used to represent the image for classification of narrow and broad weed. Results obtained suggest that the extracted 2D-DWT coefficients can uniquely represents the two different weed type.

Microstrip Antenna Design for Femtocell Coverage Optimization

A mircostrip antenna is designed for multielement antenna coverage optimization in femtocell network. Interference is the foremost concern for the cellular operator in vast commercial deployments of femtocell. Many techniques in physical, data link and network-layer are analysed and developed to settle down the interference issues. A multielement technique with self-configuration features is analyzed here for coverage optimization of femtocell. It also focuses on the execution of microstrip antenna for multielement configuration. The antenna is designed for LTE Band 7 by using standard FR4 dielectric substrate. The performance of the proposed antenna in the femtocell application is discussed along with results.

Analysis of different transparent conductive thin films element on monocrystalline silicon cell

An analysis of phase response from different types of transparent conductive thin film is presented in this paper. Surface current performance of each film which was shaped with triangular loop shape is then investigated. It has been demonstrated from the CST simulated results that element of Kapton film exhibits the best scattering parameter performance with bandwidth over 15% and linear phase range over 360°.

Left-handed metamaterial inspired by joint T-D geometry on flexible NiAl2O4 substrate

In this paper, we introduce a new compact left-handed tunable metamaterial structure, inspired by a joint T-D shape geometry on a flexible NiAl2O4 substrate. The designed metamaterial exhibits an extra-large negative refractive index bandwidth of 6.34 GHz, with an operating frequency range from 4 to 18 GHz. We demonstrate the effects of substrate material thickness on the effective properties of metamaterial using two substrate materials: 1) flame retardant 4 and 2) flexible nickel aluminate. A finite integration technique based on the Computer Simulation Technology Microwave Studio electromagnetic simulator was used for our design, simulation, and investigation. A finite element method based on an HFSS (High Frequency Structure Simulator) electromagnetic simulator is also used to simulate results, perform verifications, and compare the measured results. The simulated resonance peaks occurred at 6.42 GHz (C-band), 9.32 GHz (X-band), and 16.90 GHz (Ku-band), while the measured resonance peaks occurred at 6.60 GHz (C-band), 9.16 GHz (X-band) and 17.28 GHz (Ku-band). The metamaterial structure exhibited biaxial tunable properties by changing the electromagnetic wave propagation in the y and z directions and the left-handed characteristics at 11.35 GHz and 13.50 GHz.

28/38GHz dual band slotted patch antenna with proximity-coupled feed for 5G communication

This paper presents a slotted-rectangular patch antenna with proximity-coupled feed operated at dual band of millimeter-wave (mmV) frequencies, 28GHz and 38GHz. The antenna was built in multilayer substrate construct by 10-layers Low temperature Co-fiber Ceramic (LTCC) with 5 mils thickness each. The slotted-patch and thick substrate are configured to enhance the bandwidth and obtain a good result in gain as well. The bandwidth using are 21.3% at 28GHz and 13.0% at 38GHz with the direction gains are 8.63dBi and 8.62dBi at 28GHz and 38GHz respectively.

Cuboid dielectric resonator antenna array placed on # slots for LTE femtocell base stations

A Cuboid Dielectric Resonator Antenna fed by microstrip feed line is studied. The dielectric resonator of the antenna is made by a material with high dielectric constant ∊r=30. The impedance matching of dielectric resonator can be improved by using a # slot in the ground. In additional, a two elements array is used to enhance the performance of the antenna. This proposed antenna is suitable for long-term evolution (LTE) band 7 and LTE band 38 femtocell base stations with impedance bandwidth more than 200 MHz.

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.

Capacitive loading radiating element for reconfigurable reflectarray at Ku-band

A single-layer linearly polarized reflectarray element namely Concentric Circle Square Ring (CCSR) for Ku-band is presented in this paper. The adjustment of the reflected phase of the reflectarray element via variable capacitive loading which is realised by connecting the two rings with varactor diode. By using the full-wave EM field simulator-CST, simulation of the single element to perform exact measurement in standard waveguide were obtained. The measurement indicates that the element with attachment of varactor diode has good capability of changing the reflection phase between 0 to 20 V supplied to the diode.

Bandwidth performance analysis of different glass's dielectric permittivity on reflectarray radiating element

This paper presents the performance of bandwidth from a triangular loop shape radiating element stacked on a glass with variation of dielectric permittivity values. In this study, the dielectric permittivity value of the glass was varied from 1.5 to 10. A Kapton film (radiating element) was positioned on top of the glass and grounded with a copper layer. The radiating element was designed to operate at Ku-band frequency range. Simulation results from the CST microwave studio showed that a small dielectric permittivity value improve the reflectarray element bandwidth significantly.