Goh Chin Hock

Circuit modeling of an UWB patch antenna

An ultra wideband (UWB) patch antenna is analyzed in this paper. The design uses FR-4 substrate with dielectric constant of 4.9 and thickness of 1.6 mm. Circuit model of such antenna is developed under AWR microwave office environment. Obtained results from simulating the antenna in CST microwave studio are then compared with the results taken from the Circuit Model.

An Impulse UWB Patch Antenna with Integrated Bandpass Filter

An Ultra wideband patch antenna is tested in this paper for Impulse UWB applications. The UWB patch antenna is integrated with UWB bandpass filter of desired operating frequency range. The design is on FR-4 substrate with dielectric constant of 4.4 and thickness of 1.6 mm. Impulse performance and angle of operation for such antenna are shown.

Circuit Modeling for Rectangular Printed Disc Monopole Antenna with Slot for UWB System

In this paper, a circuit model is done for rectangular printed disc monopole antenna with slot for ultra wideband application. For this circuit modeling, patch cavity model consists of series resistor and inductor which represent the surface resistance and surface inductance with the combination of LC circuit as the resonant circuit is introduced. Moreover, a slot is etched on the patch antenna and represented by a series LC circuit for its circuit model. The result is then repeated with modification done on the slot and also the circuit model. Finally return loss result for both antenna structure and circuit model were compared and discussed.

Dielectric verification of FR4 substrate using microstrip bandstop resonator and CAE tool

This paper describes a method to determine the dielectric constant of FR4 substrate material at the operating frequency of 2.3 GHz. The method make used of computer aided engineering (CAE) tool and microstrip bandstop resonator for investigating the dielectric value of a material. In accordance with the data sheet provided by manufacturer which is 4.5 at 10 MHz, a set of preliminary dielectric values are selected in order to explain the proposed technique. Microstrip bandstop resonators with different dimension are designed and analyzed with the electromagnetic simulator. They are fabricated using conventional wet-etching process which is relatively economical compared to other method. After that, the actual responses of the square ring resonators are measured with the vector network analyzer. By matching up the simulation results to the measured results, dielectric values selected earlier are tuned accordingly. The obtained values are used to validate the accuracy of the proposed method. The method is simple to practice. It provides the beginners a fast way and relatively straightforward method in investigating FR4 materials for their research and learning.

Artificial immune system assisted Minimum Variance Distortionless Response beamforming technique for adaptive antenna system

In wireless applications, the radiation pattern of adaptive antenna system is smartly formed and steered to cancel interfering signals (placing nulls) and produces a strong peak towards the desired signal according to the calculated weight vectors. This paper proposes an enhanced beamforming technique based on Minimum Variance Distortionless Response (MVDR). The Clonal selection algorithm (Clonalg) of Artificial Immune System (AIS) has been incorporated to assist MVDR to more precisely steer its beam towards desired user and forming deeper nulls at the interfering signals. The proposed algorithm has been simulated by using uniform linear antenna with multiple array elements, with 0.5λ spacing between adjacent elements and operated in the frequency of 2.3 GHz with 20 dB noise power level. Simulation results show that AIS assisted MVDR adaptive beamforming technique is able to produce much better received SINR in comparison of conventional MVDR.

Electrical field of electrical appliances versus distance: A preliminary analysis

Every household electrical appliance that is plugged in emits electric field even if it is not operating. The source where the appliance is plugged into and the components of household electrical appliance contribute to electric field emission. The electric field may cause unknown disturbance to the environment or also affect the human health and the effect might depends on the strength of the electric field emitted by the appliance. This paper will investigate the strength of the electric field emitted by four different electrical appliances using spectrum analyser. The strength will be captured at three different distances; (i) 1m (ii) 2m and (iii) 3m and analysis of the strength of the electrical field is done based on the three different distances. The measurement results show that the strength of the electric field is strongest when it is captured at 1m and the weakest at 3m from the electrical appliance. The results proved that the farther an object is located from the electrical appliance; the less effect the magnetic field has.

Dissipation Factor Measurement of PILC Insulation at UHF

In this paper, dissipation factor measurement of Paper Insulated Lead Covered (PILC) cable insulation at ultra high frequency (UHF) is described. The material under test (MUT) is clamped between two copper sheets to form a capacitor, which is connected to the Advantest R3767CG vector network analyzer (VNA) to measure its input impedance at the resonant frequency. From the input impedance, the dissipation factor is calculated. The calculated values are then compared with data obtained from commercial system to validate the proposed method.

Design of a 5.8 GHz Rat-Race Coupler on the RO4003C® Substrate

This paper describes design of a rat-race coupler for operation at centering frequency of 5.8 GHz. The coupler is designed to have an equal power split outputs of 3 dB between output ports. Two types of power divider circuit configurations have been designed and analyzed. The coupler is designed using the electronics design automation (EDA) tool that has tuning and optimization features. The circuit design iteration and the time required have been significantly reduced as the physical dimension of the circuit is tunable. The effects of the microwave artwork on circuit performance are observed. The rat-race coupler is implemented in the microstrip line and RO4003Creg substrate is used

Design of a Beat Frequency Oscillator Metal Detector

This paper discusses the design,construction,and simulation of a beat frequency oscillator metal detector. Over the years, it has become an important issue to limit, the entry of people into certain places with weapons or instruments of harm and destruction.in this paper is a design of an effective means of detecting dangerous weapons made of metal in order to reduce crime rate in the society. It uses the principle of electromagnetic induction and adopts a digital beat frequency technique. The system uses a search coil to detect metallic objects at a close range and gives a visual, auditory and vibratory indication once the metallic object is detected. The search coil forms part of an LC oscillation circuit. The activation frequency of the LC oscillator is primarily determined by the value of involved inductor and capacitor. In case an inductance is altered, the frequency does not remain the same by changing its value through the introduction of a metallic object.

Generalized equivalent circuit model for ultra wideband antenna structure with double steps for energy scavenging

There are various types of UWB antennas can be used to scavenge energy from the air and one of them is the printed disc monopole antenna. One of the new challenges imposed on ultra wideband is the design of a generalized antenna circuit model. It is developed in order to extract the inductance and capacitance values of the UWB antennas. In this research work, the developed circuit model can be used to represent the rectangular printed disc monopole antenna with double steps. The antenna structure is simulated with CST Microwave Studio, while the circuit model is simulated with AWR Microwave Office. In order to ensure the simulation result from the circuit model is accurate, the circuit model is also simulated using Mathlab program. The developed circuit model is found to be able to depict the actual UWB antenna. Energy harvesting from environmental wirelessly is an emerging method, which forms a promising alternative to existing energy scavenging system. The developed UWB can be used to scavenge wideband energy from electromagnetic wave present in the environment.