Ahmad Nazri Dagang

A Reconfigurable Monopole Antenna With Fluorescent Tubes Using Plasma Windowing Concepts for 4.9-GHz Application

This paper aimed at investigating the performance of plasma windowing concept in terms of radiation pattern, gain, and S-parameter. The antenna structure consists of 12 tubes of commercial fluorescent lamps that contain a mixture of mercury vapor and argon gas, which upon electrification, forms plasma. After getting sufficient voltage, the gas inside the fluorescent tube will ionize to plasma and form a plasma column. When all of the tubes surrounding the antenna are electrified, the radiation is trapped inside. By leaving one or more of the tubes in a nonelectrified state, apertures are formed in the plasma shield, which allow radiation to escape. The plasma frequency in this experiment is equal to 5.634e11 Hz. This antenna design is at 4.9 GHz. The designing of plasma antenna using fluorescent tubes has created advancement in antenna industry especially in reconfigurable antenna field.

Mercury-free electrodeless discharge lamp: effect of xenon pressure and plasma parameters on luminance

Since there is much concern about environmental preservation, the authors have paid attention to the uses of mercury in lighting application. They have focused on the application of the xenon low-pressure inductively coupled plasma (ICP) discharge in developing cylindrical type mercury-free light sources. ICP can be operated at low filling gas pressures and demonstrates significant potential in producing high density plasma. Xenon pressure was varied from 0.1 to 100?Torr and the lamp luminance was measured. The gas pressure dependence shows an increase in luminance at pressures below 1?Torr. In order to clarify this behaviour, measurement of plasma parameters was carried out using the double probe method and its relation to lamp luminance is discussed. As the gas pressure is decreased (from 1 to 0.01?Torr), the electron temperature increases while the electron density decreases while at the same time the lamp luminance increases. There are several factors that are believed to contribute to the increase in luminance in the very low pressure region. Increases in luminance are considered to be due to the electron?ion recombination process which brings a strong recombination radiation in continuum in the visible region and also due to the effect of stochastic heating.

Electrical Conductivity and Hall Effect Study of Organic Solar Cell Using Downy Rose Myrtle Berries as Natural Dye: A Heat Treatment

This work focused on the electrical and Hall Effect of Organic Solar cell (OSC). In this work, Indium Tin oxide (ITO) glass as substrate was heated at 50 °C to 200 °C. The polymer used was Poly (3-Dodecylthiophene) (P3DT) thin film and Downy Rose Myrtle berries (RhodomyrtusTomentosa(Ait.) Hassk.) as dye. The P3DT were deposited on the ITO substrate using electrochemistry method at room temperature. While, the dye of Downy Rose Myrtle berries was deposited by layered using spin coating method. The electrical conductivity of ITO deposited thin film was explored by four point probes (FPP) under dark and under light radiation (range of 10 Wm-2 to 200Wm-2). From FPP study, the electrical conductivity was increased by the increment of light intensity and temperature of substrate. Lastly, the samples were examined using Hall Effect measurement to obtain the type of sample, Hall mobility, and highest charge carrier in the sample of OSC. The results show that the sample is suitable for further solar cell application.

A reconfigurable monopole antenna with fluorescent tubes by using plasma windowing concepts at 4.9GHz

This research aimed at investigating the performance of plasma windowing concept in terms of radiation pattern, gain and return loss. The antenna structure consists of 12 tubes of commercial fluorescent lamps that containing the mixture of mercury vapour and argon gas which upon electrification, forms plasma. After get sufficient voltage the gas inside the fluorescent tube will ionize to plasma and formed plasma column. When all of the tubes surrounding the antenna are electrified, the radiation is trapped inside. By leaving one or more of the tubes in a non-electrified state, apertures are formed in the plasma shield which allows radiation to escape. The plasma frequency in this experiment is equal to 5.634e11 Hz. This antenna design at 4.9 GHz. The advantages from this research, the design and construction of plasma antenna with fluorescent tubes can be beneficial in term of advancement in antennas technology especially in reconfigurable antenna.

Fabrication and characterization of titania/poly (3-dodecylthiopene)/red seaweed as hybrid solar cell

In this research, hybrid solar cells which consist of a combination of organic red seaweed (RS) (Kappaphycus alvarezii) and poly (3-dodecylthiophene) (P3DT) with inorganic titania nanocrystals (TiO2 NCs) materials are fabricated. These hybrid solar cells are fabricated in bilayer heterojunction of ITO/TiO2 NCs/P3DT/RS/Au via electrochemistry method using Electrochemical Impedance Spectroscopy (EIS). The optical, electrical properties and power conversion efficiency (PCE) of these hybrid solar cells that can absorb over a broad range of light spectrum were studied. The UV-Vis spectra showed that TiO2 NCs, P3DT and RS were absorbed over a wide range of light spectrum which were 200-300 nm, 300-900 nm and 250-670 nm; respectively. The FTIR spectra of the RS showed the presence of carbonyl and hydroxyl group which was responsible for a good sensitizer for these hybrid solar cells. The electrical conductivity of ITO/ (1) TiO2 NCs/P3DT/RS thin film under the light radiation of 100 Wm−2 was 0.288 Scm−1, while fo...

Hybrid thin films based on bilayer heterojunction of titania nanocrystals/polypyrrole/natural dyes (Kappaphycus alvarezii) materials

In this research, hybrid thin films which consist of a combination of organic red seaweed (RS) (Kappaphycus alvarezii) and polypyrrole (PPy) with inorganic titania nanocrystals (TiO2 NCs) materials were fabricated. These hybrid thin films were fabricated accordingly with bilayer heterojunction of ITO/TiO2 NCs/PPy/RS via electrochemical method using Electrochemical Impedance Spectroscopy (EIS). The effect of number of scans (thickness) of titania on optical and electrical properties of hybrid thin films were studied. TiO2 NCs function as an electron acceptor and electronic conductor. Meanwhile, PPy acts as holes conductor and RS dye acts as a photosensitizer enhances the optical and electrical properties of the thin films. The UV absorption spectrum of TiO2 NCs, PPy and RS are characterized by UV-Visible spectroscopy, while the functional group of RS was characterized by Fourier transform infrared spectroscopy (FTIR). The UV-Vis spectra showed that TiO2 NCs, PPy and RS were absorbed over a wide range of li...

Effect of Plasma Parameters on Monopole Plasma Antenna Performance

The research is focused on determining the plasma parameters such as electron temperature and density, and plasma and collision frequencies, that can be applied on plasma antenna simulation. From the characteristics of plasma parameters obtained, the antenna parameters are then investigated. The Ar-Hg discharge tube is used, and energized by using a high voltage power supply. The plasma parameters are obtained by using numerical programming namely Glomac based on the different voltage, current, pressure and size diameter of the discharge tube. Plasma antenna parameters are characterized by using Computer Simulation Technology (CST) software with different plasma frequency, gas pressure, tube size and material used to analyze the antenna performance. The plasma and collision frequencies are calculated based on the plasma parameter obtained from Glomac programming. It shows that the electron temperature decrease while electron density increase when the current is increased. The gas pressure and diameter of tubes are also influences the plasma parameters. From CST simulation, the antennas performance can be analyzed in terms of return loss, resonant frequency, bandwidth, gain, and radiation pattern. The plasma frequency increase when the electron density increases. By changing the plasma frequency, gas pressure and tube diameter, the antenna performance can be improved in particular at their return loss, gain, directivity and conductivity. In addition, the efficiency of the plasma column as a radiating element is related to the conductivity of the plasma. From this study, the characteristics of the monopole plasma antenna is investigated and evaluated.

Study of the characteristics of reconfigurable plasma antenna array

This paper presents a design and simulation of a reconfigurable array of plasma antenna. The plasma column is used as radiating elements instead of metal to create an antenna. The advantages of the plasma antenna over the conventional antenna are its possible to change the operating parameters, such as the working pressure, input power, radius of the discharge tube, resonant frequency, and length of the plasma column. In addition, plasma antenna can be reconfigurable with respect to shape, frequency and radiation parameters in a very short time. The plasma discharge tube was designed with a length of 200 mm, the radius of the plasma column was 2.5 mm and the coupling sleeve was connected to the SMA as the ground. This simulation was performed by using the simulation software Computer Simulation Technology (CST). The frequency is set in the range of 1 GHz to 10 GHz. The performance of the designed antenna was analyzed in term of return loss, gain and radiation pattern. For reconfigurable plasma antenna arr...

Analysis of reconfigurable line pattern of capillary plasma antenna array

Simulations by applying Computer Simulation Technology (CST) Microwave Studio have been done towards Hg-Ar (10 Torr and 20 Torr) capillary tubes. These capillary tubes which are 5 mm in diameter are designed as plasma antenna monopole antenna and antenna arrays (four line array, six line array and nine line array). They have been arranged in the two different dimensions, 4mm × 4mm and 8mm × 8mm. Their performance as an antenna have been analyzed and compared. The reconfigurable characteristics of these kinds of plasma antenna such as gain, directivity and return loss are calculated. The results of gain and directivity of 10 Torr of plasma antenna are stronger than 20 Torr in the 4mm × 4mm dimension. Return loss of these kinds of plasma antenna significantly dropped in different operating frequencies of microwave ranges make them suitable to be applied for multiple applications in antennas or telecommunications field. Gas pressure of plasma antenna and array distance between the capillary tubes give a sign...

RF Radiation Behavior of Rare Gas in Plasma State

This paper analyzed the performance of monopole plasma antenna based on RF charging using different number of turns of coupling sleeve and different gases. The plasma antennas were designed with 3 different gases which are argon, nitrogen and fluorescent with pressure 10 Torr. For argon plasma antenna, different pressure was designed to analyze the performance of plasma antenna with pressure 0.5 Torr, 1 Torr, 5 Torr and 10 Torr. The dimension of discharge tube for argon and nitrogen is 130 mm length and 10 mm diameter, while for fluorescent 145 mm length and 12 mm diameter. The dimension of commercialize fluorescent were used as benchmark for other plasma antenna. The commercially fluorescent tubes contain mixture of vapour mercury and argon. The plasma antennas were driven by radio frequency (RF) to sufficiently ionize the gas inside the tube to convert them into plasma state. Each antenna with different configuration of type of gas and pressure was tested while varying the number of coils turns. The antenna’s capability to operate as transceiver was verified through simulation by using CST Microwave Studio.