Mohamad Zoinol Abidin Abd Aziz

RF receiver system design for Wireless Local Area Network bridge at 5725 to 5825 MHz

In data communication system, the outdoor of Wireless Local Area Network (WLAN) technology can be implemented in bridge connection. It allows LANs in separated buildings to be connected over the distance ranging in several hundred meters. In RF system design level, the performance of the WLAN bridge also relies on the RF receiver system where it must be well designed to minimize distortions in the system. This paper presents a RF receiver system design for WLAN bridge at 5725 - 5825 MHz based on IEEE 802.11a standard. At 54 Mbps data rate, the receiver can receive minimum input power of -69.1 dBm with 19.84 dB SNR and 47.3 dB dynamic range which is comply with the standard. Beside that, the prototype of the RF receiver has been measured to verify with the simulation results in terms of gain compression and spurious responses.

Circular Polarized Patch Antenna for 1.8 and 2.4 GHz Applications

This paper presented a patch circular polarized antenna for GSM technology at 1.8 GHz and WLAN technology at 2.4 GHz. A traveling wave microstrip array antenna consisting of square truncated patch operated as circular polarized has been designed, fabricated and measured. The inter element spacing; length and width of the square and circular patches of the array antenna were optimized by successive simulations using the CST software. This antenna had radiated at 1.8 and 2.4 GHz of resonant frequency with −38.563 and −24.967 dB of return loss respectively. The axial ratio for RHS circular polarized is 0.95 < 3 dB at 2.4 GHz.

Investigation of triangular, circular and ellipse slots of Vivaldi antenna

This paper discussed on simulation investigation of triangle slot, circular slot and ellipse slot of Vivaldi antenna in term of bandwidth, reflection coefficient, gain and directivity which is operated at frequency of 10 GHz. Firstly, a normal Vivaldi antenna using FR-4 substrate had been designed and the single slot and double slot is developed. The double ellipse slots from 1mm to 5mm the gain and directivity increase from 5.460 dB to 6.805 dB and from 5.699 dBi to 7.136 dBi within their respective operating band. The advantages of a Vivaldi antenna such as simplicity, wide bandwidth, and high gain at microwave. This proposed antenna had been designed and simulated using Computer Simulation Technology (CST) simulation software.

Dual-Band Copper Rod Monopole Antenna for Wireless Communication System

In this paper, a dual-band copper rod monopole antenna for a wireless communication system is initiated. The antenna has been designed based on meander line technique using the monopole rod elements and rectangular ground structure. Each element of meander lines was designed with a half wavelength to radiate at a frequency of 2.4 and 5.8 GHz for Wireless Local Area Network (WLAN) application. The proposed antenna was designed and simulated by using Computer Simulation Technology (CST) software. The bandwidth of reflection coefficient of less than −10 dB could be observed at (f1–f2) 331 MHz and (f1–f2) 358 MHz for Design A. Then, the additional cone and inverse-cone shape reflector shifted the frequency to the left from the 2.4 GHz band and to the right at 5.8 GHz band. The desired frequency could be obtained by adjusting the size of the copper reflector.

Design Tri-Band Fractal Antenna with Minkowski Island Split Ring Resonator Structures

The paper investigates the effect of Minkowski Island split ring resonator (MI-SRR) on the microstrip fractal patch antenna. Firstly, a basic Minkowski Island had been simulated in the CST Microwave Studio. Then, the addition of several sizes of the Minkowski Island split ring resonator on the substrate had been generated tri-band resonant frequencies. The optimal result of this tri-band antenna 2.394 GHz, 3.528 GHz and 5.257 GHz with a gain of 0.874 dB, 1.41 dB and 2.94 dB and the reflection coefficient magnitudes of - 21.945 dB, - 17.154 dB and – 16.536 dB. The reflection coefficient magnitudes of the simulation and fabricated antenna also had been compared. The target application for this antenna is for WLAN and WiMAX.

Investigation of impedance modeling for a unit cell of the circle loop Frequency Selective Surface at 2.4GHz

In this paper, we present a mathematical impedance modeling for a unit cell of the circle loop Frequency Selective Surface (FSS) structure. The unit cell of the circle loop FSS is designed and simulated based on industrial, scientific and medical bands (ISM) standard by using the CST Microwave Studio software. The configuration of FSS is simulated for two types; single layer and dual layer FSS. Based on physical parameters of the design structure of the FSS, real and imaginary component of the design has been modeled mathematically.

Feed lines effects on UWB double sided circular disc bow-tie antenna

In this paper, presented a single double-sided circular disc bow-tie antenna for Ultra Wide Band (UWB) communication is being proposed. The antenna covers the UWB spectrum from 3.1 to 10.6 GHz, and had a return loss below than 10 dB throughout the entire band. The antenna feed lines were analyze in order to maximize the performance of UWB antenna. A compact antenna area of 30.0 × 60.0 mm2 is obtained. The material used is FR-4 epoxy glass substrate that has dielectric constant, εr = 4.4 and the dielectric thickness; h =1.6mm. The antenna also gives omni directional radiation characteristics with reasonable gain values over the same frequency band.

An investigation of drugs detection technique using RF radiation exposure in room temperature

In this technical paper contains the information of the Radio Frequency (RF) exposure along 10 MHz to 3 GHz frequency on pharmaceutical medicine where in this testing Paracetamol were tested. The samples were prepared at five different mol (10, 20, 30, 40 & 50 ml) and three different distances (5, 10, 15 cm) between horn antenna and the samples. The reactions from the medicine due to RF radiation are measured at S11 by fixed distance versus varied mol and fixed mol versus varied distance. The quasi-static technique and the RF exposure results, with respective specification was included and discussed.

Design of Low Noise Amplifier for Radio over Fiber at 5.2 GHz

This paper presents the design and simulation of low noise amplifier (LNA) used in an active radio access point (RAP) for Radio over Fiber (RoF) technology at 5.2 GHz. RoF is integration of optical fiber for radio signal transmission within network infrastructures that is considered to be cost effective, practical and relative system configuration for long haul transport of millimeter frequency band wireless signal. The LNA designed function is to amplify extremely low signals without adding noise, thus preserving the required Signal Noise Ratio (SNR) of system at extremely low power signal. The implementation of design is based on Agilent ATF-5143 transistor and Microwave Office software is used to perform the simulation in S-parameters. The design and simulation process including selecting the transistor based on RoF requirements, stability of transistor, matching network, biasing and optimization. The design has shown an acceptable behavior with gain of 16.046 dB and noise figure of 0.9368 dB using conjugate matching method.

Emission heights of narrow bipolar events in a tropical storm over the Malacca Strait

Emission heights for narrow bipolar events (NBEs) have been reported mostly from observations at mid latitudes but none have been reported from tropical regions. In this paper, we are reporting for the first time the heights of NBE emissions from a tropical storm over the Malacca Strait, a narrow water passage between the Malay Peninsula and Sumatra Island. A total of 49 positive NBEs (+NBEs) were detected from the storm. The NBE activity can be divided into two stages according to the emission heights and radar reflectivity data. The first stage (or S1) lasted for only 6 minutes, started with the first detected NBE, and produced 20 NBEs (41%). The emission heights ranged between 12.0 and 16.7 km. Radar reflectivity data showed that the storm reached maximum values at 55 dBZ within the period S1. In contrast, the second stage (S2) lasted longer (32 minutes) and produced 29 NBEs (59%). The emission heights were lower and ranged from 8.5 to 13.7 km. Radar reflectivity data showed that the storm reached maximum values at 50 dBZ within the period S2.