N. H. Abd Rahman

Frequency reconfigurable aperture-coupled microstrip patch antenna using Defected Ground Structure

This paper designs and simulates frequency reconfigurable microstrip patch antenna using Defected Ground Structures (DGS) with aperture coupled feed line. Single element with two regular slots etched on the ground layer has been designed to represent two resonant frequency 7.5 GHz and 8.85 GHz. Comparison two antenna designs without and with DGS structure is reported in this paper. Simulated results shows that etched DGS structure on the ground plane can eliminate one of the resonant frequencies. Effect of DGS structure on the designed antenna based on switching mode at the feed line.

An alternative approach to design conductive hybrid cover yarns for efficient electromagnetic shielding fabrics

E-Textiles have gained enormous attention due to their specific characteristics in various non-conventional applications such as electromagnetic shielding materials. With the advent of various high frequency-driven devices, the need to restrict the non-ionizing radiations from their undesired effects became imperative. Due to the ease of production, better electrical conductivity and durability, the conductive hybrid cover yarns with continuous metallic filaments have earned its place as the most convenient form of yarns to develop E-textiles. However, controlling the amount of conducting material in yarns poses a challenge as the increase in size of the metallic filaments are associated with reduced electromagnetic shielding effectiveness due to increased stiffness of yarns, which resists in proper interlacement and hence causes openness in fabrics. The proposed design of conductive hybrid cover yarns is proven to have better tensile properties and modulus, therefore this design is more suitable to produced fabrics with higher cover factors. The amount of conducting material in the proposed design increased significantly without changing the size of the continuous filaments. Moreover, 99.9% shielding effectiveness is achieved with this increased metal content in fabrics in S-band and partly C-band microwave frequencies.

Achievement of a bifurcated beam by a bend array configuration

For the next generation (5G) mobile base station antennas, authors are developing a cylindrical lens antenna featuring a simple configuration compared to the present array antenna configuration. In order to achieve a cylindrical lens antenna, feed element should produce a bifurcated beam radiation. In this paper, the bifurcated beam is conformed by a bend array configuration. Relations of array element number and objective beam shape are investigated.

Accurate feed position designing for Malaysia beam coverage

For satellite communication, precise Malaysia coverage is requesting. In this paper, multi beam coverage is studied. In order to arrange multi beams at exact positions, exact feed position are determined through focal region ray tracings. Then, a multi beam reflector antenna is designed and beam allocations are examined. Adequateness of feed position determination is ensured by exact beam position achievement.

Accuracy estimations of a negative refractive index cylindrical lens antenna designing

In order to conform mobile base station antenna simply for the next generation mobile system (5G), a cylindrical lens antenna is developing. For the lens material, negative refractive index is used so as to reduce lens thickness. In this paper, relations of lens parameters and lens shapes are investigated. Design parameters for achieving practical thin lens shapes are clarified. Moreover, lens shaping accuracies are investigated through checking the refractive angles or ray paths on lens surfaces. All refractive angle results agree very well with the theoretical value. Adequateness of lens shaping results is ensured.

Simulation of radiation pattern reconfigurable microstrip patch antenna using feeding delay line technique

This paper proposes radiation reconfigurable patch antenna using feeding delay line technique. By using simulation and optimization from Computer Simulation Technology (CST) the 2 × 2 antenna array is designed and investigated. The direction of radiation pattern is controlled by interchanging two different lengths of corporate feeding network using OPEN and SHORT states of feeding line network. Working at 7.5 GHz for meteorology application, three directions of radiation pattern are obtained from the proposed reconfigurable antenna according to the states of feeding line network, −30 degree, 0 degree and +30 degree. Good results from the simulation and optimization analysis promise the feasibility of the proposed technique.

Design of serial feeds for a bifurcated beam of bend-array configuration

This paper presents the design of serial feed radiators in cylindrical lens antenna system for mobile base station application. The authors are developing a cylindrical lens antenna featuring a simple configuration compared to the present array antenna configuration. In order to achieve the cylindrical lens antenna, bifurcated beam radiation shall be produced by the feed elements. In this paper, the bifurcated beam is achieved by adopting a bend-array configuration, consisting of four rectangular array elements with serial feed network. To ensure good and balance performance of the array antenna, the orientation of electric fields and the excitation amplitude of each element are considered. The optimized array structure is then arranged in bended structure to obtain the bifurcated beam pattern. To verify the radiation characteristic, simulation result of the bifurcated beam radiation is shown in terms of the current distribution. Good agreement between the beam pattern and the current distribution is obtained, showing that the serial feed network is accurate and effective to produce the bifurcated beam radiation for cylindrical lens antenna system.

Beam scanning of phased array antenna using phase modification method for satellite application

This paper presents the design of a 1×4 microstrip array antenna operating at 6.3GHz for C-band communication satellite application. The project aims to investigate the ability of the array to control the direction of the main lobe through a systematic least mean square method and to validate the design through accurate electromagnetic analysis. The array element consists of rectangular microstrip patch fed by inset feed. The single rectangular microstrip patch size and feed position is obtained by theoretical calculation, MATLAB and CST Studio software simulation. Based on the single element design, an array of four elements with equal sizes and spacing is designed. The desired beam direction is determined through passive feed control of the transmission line length to adjust the phase of the radiation pattern. A good performance antenna with 10.78dB gain and 42.46% efficiency is produced. A clear relation between phase coefficient and beam direction has been achieved.

The recognition of biocomposite antenna substrate via coaxial probe method and substrate sensor

The research paper covered two novelty that measures the dielectric properties by using the coaxial probe method for 1 GHz to 20 GHz and recognition of the proposed substrate by using substrate sensor circuit. The dielectric properties measurement involved KEYSIGHT 85070E probe kit and the substrate recognition circuit using the microcontroller PIC16F877A with light depending resistor sensor. The substrate sensor used visibility method to cascade the analogue input with the changes of the light source. The stability output for dielectric constant (1.86 to 3.45) and loss tangent (0.0066 to 0.0754) obtained for five different compositions of biocomposite antenna substrate. Besides that, the recognition of the proposed substrate succeeded with the microcontroller recognise each of the substrates and display via a liquid crystal display the type of proposed substrate according to the composition. The stability of the dielectric properties measurement results distributes by the implementation of measuring tool to overcome the warping issue. The circuit performed as expected to recognise each of the proposed substrates and offer portability for the substrate recognition process.

Optimized parabolic reflector antenna for Malaysia beam coverage

Reflector antennas remain the most preferred option for satellite communication. However, some applications require the beam to be shaped precisely to the specific coverage region in order to provide high data rate services with constant signal availability. As for small region like Malaysia, it is very crucial to obtain precise beam shaping because it is located nearby other countries thus, unnecessary radiation power over undesired nearby regions shall be reduced. The shaped footprint is designed by using multi beam technique where many feed horns are employed. In previous designing, severe horn overlapping were shown and this problem has been analytically studied by the relation between the feed horn size and feed position displacement. The relation of feed horn size and feed position displacement is numerically clarified with parameter of the beam separation angle and the focal-length-to-diameter ratio (F/D) of a parabolic reflector. As a result, antenna structure for escaping feed horn overlapping are obtained.