Nur Emileen Abd Rashid

Enhancement of bandwidth through I-shaped Defected Ground Structure

This paper discuss on a rectangular microstrip patch antenna incorporated with I-shaped Defected Ground Structure (DGS) metamaterial which exhibit an enhancement of 118% bandwidth compared to the conventional design. The antenna is designed for S-band application, resonates at 2.45 GHz. The I-shaped DGS shows the metamaterial characteristics with negative permeability, μ and permittivity, ε through Nicolson-Ross-Weir method. The circuit was designed using Computer Simulation Technology (CST) Microwave Studio. Based on the simulation, the antenna also shows other improvement in term of gain and return loss of 17.6% and 71.89%, respectively. The Size of the radiating patch was also reduced for about 21% The performance of the fabricated antenna such as antenna gain, return loss, bandwidth and directivity were also measured using the Vector Network Analyzer (VNA) for a verification.

Multilayer dual-mode dual-band bandpass filter

This paper presents a single ring resonator using multilayer technique for dual-band bandpass filter. The resonator is composed of two resonators with each one having a quarter-wavelength coupled-line connected in series to a transmission line. The two resonators are arranged in parallel to form a single ring dual-band bandpass filter topology. The controlling impedance parameters of this ring are Zr for the transmission line and even- and odd-mode characteristic impedances i.e. Zoe and Zoo for the coupled-lines. Observations on the controlling parameters are conducted to investigate the effect of each parameters in terms of bandwidth, matching level and the transmission zeros. For validation, the filter is realized using multilayer technique, designed at 2 GHz on FR-4 microstrip substrate. The results exhibited good isolation between the two passbands with centered transmission zero attenuated above 40 dB while the centered frequencies were found at 1.59 GHz in the first passband and 2.41 GHz in the second passband. The simulated and measured result is presented throughout this paper to validate the concept.

Properties of dielectric combline resonator for base station filters

This project mainly looked at combline resonators; such resonators are based on quarter wavelength long coaxial structures, and also considered the design tradeoffs in dielectric combline resonators to achieve higher Q for base-station filters in mobile communication. Changing the design of conventional combline resonators, by replacing the metallic inner with a dielectric inner, achieves a higher Q without increasing the volume of the resonator. The design tradeoffs in frequency and Q for the TM mode are examined with the aid of an EM modelling package.

Reconfigurable ring filter with controllable frequency response.

Reconfigurable ring filter based on single-side-access ring topology is presented. Using capacitive tuning elements, the electrical length of the ring can be manipulated to shift the nominal center frequency to a desired position. A synthesis is developed to determine the values of the capacitive elements. To show the advantage of the synthesis, it is applied to the reconfigurable filter design using RF lumped capacitors. The concept is further explored by introducing varactor-diodes to continuously tune the center frequency of the ring filter. For demonstration, two prototypes of reconfigurable ring filters are realized using microstrip technology, simulated, and measured to validate the proposed concept. The reconfigured filter using lumped elements is successfully reconfigured from 2 GHz to 984.4 MHz and miniaturized by 71% compared to the filter directly designed at the same reconfigured frequency, while, for the filter using varactor-diodes, the frequency is chosen from 1.10 GHz to 1.38 GHz spreading over 280 MHz frequency range. Both designs are found to be compact with acceptable insertion loss and high selectivity.Reconfigurable ring filter based on single-side-access ring topology is presented. Using capacitive tuning elements, the electrical length of the ring can be manipulated to shift the nominal center frequency to a desired position. A synthesis is developed to determine the values of the capacitive elements. To show the advantage of the synthesis, it is applied to the reconfigurable filter design using RF lumped capacitors. The concept is further explored by introducing varactor-diodes to continuously tune the center frequency of the ring filter. For demonstration, two prototypes of reconfigurable ring filters are realized using microstrip technology, simulated, and measured to validate the proposed concept. The reconfigured filter using lumped elements is successfully reconfigured from 2 GHz to 984.4 MHz and miniaturized by 71% compared to the filter directly designed at the same reconfigured frequency, while, for the filter using varactor-diodes, the frequency is chosen from 1.10 GHz to 1.38 GHz spreading over 280 MHz frequency range. Both designs are found to be compact with acceptable insertion loss and high selectivity.

The influence of different baseline lengths to ground target signature in a FS micro-radar network

A Forward Scatter Radar topology based on two-ray path propagation configuration is discussed. Based on this configuration, a study on the influence of different targets crossing baseline lengths to the targets spectra in Forward Scatter Radar (FSR) is conducted. By using simulated and measured signals, it was observed that, the stability and similarity of targets power spectra depends on the baseline length. The employment of baseline normalization procedure is shown to improve significantly the differences in the spectra.

Improvement of Doppler measurement using multiple-input multiple-output (MIMO) concept in radar-based automotive sensor detecting pedestrians

Purpose This paper aims to present an approach of utilizing multiple-input multiple-output (MIMO) radar concept to enhance pedestrian classification in automotive sensors. In a practical environment, radar signals reflected from pedestrians and slow-moving vehicles are similar in terms of reflecting angle and Doppler returns, inducing difficulty for target discrimination. An efficient discrimination between the two targets depends on the ability of the sensor to extract unique characteristics from each target, for example, by exploiting Doppler signatures. This study describes the utilization of MIMO radar for Doppler measurement and demonstrates its application to improve pedestrian classification through actual laboratory measurements. Design/methodology/approach Multiple non-modulated sinusoidal signals are transmitted orthogonally over a MIMO array using time division scheme, illuminating human and non-human targets. The reflected signal entering each of the receiving antenna are combined at the radar receiver prior to Doppler processing. Doppler histogram was formulated based on a series of measurements, and the Doppler spread of the targets was determined from the histograms. Results were compared between MIMO and conventional single antenna systems. Findings Measurement results indicated that the MIMO configuration provides able to capture more Doppler information compared to conventional single antenna systems, enabling a more precise discrimination between pedestrian and other slow-moving objects on the road. Originality/value The study demonstrated the effectiveness of using MIMO configuration in radar-based automotive sensor to enhance the accuracy of Doppler estimation, which is seldom highlighted in literature of MIMO radars. The result also indicated its usefulness in improving target discrimination capability of the radar, through actual measurement.

Intelligent Management System for Home Appliances A conceptual approach using Hardware Description Language

IoT (Internet of Things) is an emerging trend in the market and smart appliances are a subset of IoT. The IoT helps integrate digital and wireless technologies in home or kitchen appliances. Furthermore, M2M (Machine to Machine) communication is likely to create a key opportunity in the smart appliances market. Smart appliances are the next generation of home appliances that have the ability to receive, interpret, and act on a signal received from a user. This paper is a demonstration of designing a multipurpose remotely controlled system for electrical household appliances. The project simulation design is carried out by Hardware Description Language (HDL) programming.

Miniaturization of printed monopole antenna through fractal geometry and partial cutting methods for UHF application

This paper reports an investigation on a combination of fractal geometry and half cutting methods in designing a printed monopole antenna for low frequency application. The effects of the combination of fractal shape and partial cutting methods to the printed monopole antenna performances were studied. All designs operate at the Ultra High Frequency (UHF) band. The fractal geometry was proposed in order to shift down the resonant frequency while partial cutting method helps to a further reduction of the overall size of the antenna. Based on the results, it was found that the overall size of the proposed antenna is 53.68 % smaller than the conventional printed monopole antenna at the same resonant frequency. The monopole antenna size is 70.89 × 135.82 × 1.67 mm3. It has gain of 2.72 dBi with omnidirectional radiation pattern.

Single ring dual-band bandpass filter with meander for 2.5 GHz and 5.2 GHz

A single ring resonator dual-band bandpass filter using quarter-wavelength resonators suitable for WLAN application is presented in this paper. Both side of ring resonator consist of quarter-wavelength parallel coupled-lines. In further reducing the size of the filter, meander structure is applied to an existing design. Using different number of meander slots, a microstrip dual-band single ring resonator are applied and realized on FR4 substrate to suite filter operating at 2.5 GHz and 5.2 GHz. Simulation is carried out in analyzing the performance of the design using high frequency system simulation software and fabrication is done to validate the topology.

Single mode ring resonator with harmonic suppression

A single-side-access ring resonator for bandpass filter is presented. The characteristics of the resonator were investigated in terms of width and gap of the ring line and coupled-lines on microstrip. It is found that the frequency response and bandwidth of the resonator can be controlled by controlling the width and gap of the ring elements. The resonator was tested on Tachonic substrates and simulated using em fullwave simulator for verification. The response showed that at higher side of out-of-band frequency response, the resonator suffered with spurious effect. To improve the effect, a 3rd order low pass filter was introduced which eventually modifies the ring structure. To validate the concept, the modified ring resonator was fabricated on Tachonic and the results showed improvement of spurious effect as compared to the nominal ring resonator. The rejection level of 30 dB was found at 4.34 GHz compared to the nominal design at 4.99 GHz with parasitic resonance at 2fo had been successfully suppressed more than 20 dB. Based on this modified structure, the size had been reduced by 13.42 % compared to the nominal ring resonator.