Azahari Salleh

The study of X-circular polarized by using double circle slot at 2.4 GHz

This paper discussed the study on the circular polarized patch antenna by using double circle slot technique in single patch and X-polarized patch antenna. The operating frequency for the proposed antenna is 2.4GHz with 29.86MHz of bandwidth and return loss is -34.85dB. The antenna had been designed and simulated using CST Microwave Studio simulation software. The circular polarization (CP) operation was obtained by implemented double circle slot at center of circular patch antenna. Based on simulation, it obtained a gain of 6.79dB with minimum axial ratio (AR) is 1.75dB and a 3db AR bandwidth of 214.7MHz.

Intermodulation distortion of Integrated Power Amplifier and filter using single stub tuners for green communication

Integrated Power Amplifier (PA) and filter which is part of important component for Radio Frequency (RF) transmitter is designed using Adavance Design Simulation (ADS). The main aims of the design is to provide linear amplifier and filter at the center frequency of 2 GHz and biased at the conditions of class AB. GaAs transistor is used as an active device due to ability in operating at high frequencies and can generate signals with lesser noise. Linearity of the integragted design was simulated with two tone test and the intermodulation products (OIP3) value resulted to be 50 dBm. ACPR of -50.86 dBC with 10MHz frequency spacing is achieved using the Butterworth Bandpass Filter. On the other side, high linearity will lead to more efficient transmission of the signals.

X band parallel coupled- line with dumbbell dgs filter for radar applications

Microwave filter is a kind of device, which can separate microwave signals with different frequencies. The filter has been utilized widely in many fields such as communication, signal processing, radar and other related fields. An X-band filter using parallel coupled-line technique with DGS is designed. The purpose of this paper is to observe the performance of band-pass filter with defected ground structure operating at a frequency of 10G Hz. The filter designed is run by simulation using Advanced Design System (ADS). Initially, the mid-band frequency is set to 10G Hz. The filters design and structure is based on the Chebyshev prototype characteristic. The characteristics can be visualized through the response of the reflection coefficient and transmission coefficient.

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.

INVESTIGATION OF DUAL MEANDER SLOT TO MICROSTRIP PATCH ANTENNA

A dual microstrip meander slot antenna is presented for Wireless Local Area Network (WLAN) application. The proposed antenna comprises a rectangular microstrip patch element embedded with two meander slots. The parametric study is performed to investigate the characteristics of microstrip patch antenna with double meandered slots compared to one without any meander slot. Microstrip patch antenna with dual meander slot can achieve return loss until -24.54dB. However, the gain of dual meander slot antenna is lower than the rectangular antenna. Other antenna parameters are also has been investigated such as bandwidth, radiation pattern and and directivity throughout simulation and measurement process. The proposed antenna has been designed and simulated by using CST Studio Suite 2010.

Integrated low noise amplifier with notch filter using DMS technique for ultra-wideband application

The work presents a design of single stage integrated low noise amplifier using negative feedback and inductive source degeneration with DMS technique as the notch filter. Implementation of Super-low noise InGaAs HEMT MGF4937AM transistor which covers from 3.1-10.6 GHz for LNA. Due to interference from IEEE 802.11 WLAN at 5-6 GHz in UWB standard, a notch filter is used to attenuate the undesired frequency band from the LNA. Introducing negative feedback and inductive source degeneration improve the stability of the LNA at the same time provide wideband characteristic and gain flatness for the entire band. DMS technique used as notch filter because of its microstrip characteristic which easily to integrate with other microstrip devices. This LNA integrated notch filter design is based on FR4 microstrip and designed using Advanced Design System (ADS) software. The LNA integrated notch filter provides an input return loss (S11), output return loss (S22) which less than -10 dB, the gain (S21) more than 10 dB and noise figure less than 2 dB from 3.1 to 5 GHz. From 5-6 GHz, the gain and noise figure is degrading which indicate that the particular frequency band is rejected. From 6-10 GHz, all the parameters return as the original signal.

CPW-FED compact monopole antenna for dual-band WLAN/ WiMAX applications

This paper has presents a novel design of compact monopole antenna fed by a coplanar waveguide (CPW) for dual-band applications that targeted to achieve the gain more than 1 dB. The proposed compact monopole antenna has been design only 20 × 35 mm in size. The monopole structure with two inverted U-shaped, L-shaped lateral and coplanar-way (CPW) feed line driven by 50 Ω on one side are designed with reflection coefficient that |s11| less than -10 dB. The U-shaped patch and patch laterally inverted L-shaped have been applied to generate different frequency bands 2.4 GHz and 5.2 GHz by controlling the parameter. According to the simulation and measurement result, the reflection coefficient bandwidth is about 8 - 16.51 % at both frequencies. The measured gain of the monopole is 1.18 dB at 2.4 GHz and 1.45 dB at 5.2 GHz. The proposed antenna has increased the gain and reduces the reflection coefficient as well as increases the bandwidth of the antenna.

Design 2 × 2 patch array with L Slot Antenna for WiMAX and WLAN

A dual-band antenna by use 2 × 2 patch array with L-slot is presented for simultaneously worldwide interoperability for Microwave Access (WiMAX) and wireless local area network (WLAN) application. This 2 × 2 Patch Array with L Slot Antenna is targeted to achieve the gain more than 2 dB for both frequencies by using array technique design. The antenna design structure has been modified by adding a small double L-slot inside inverse double L-slot to obtain the second band resonant frequency at 3.6 GHz for WiMAX respectively. The proposed microstrip patch array antenna comprising of four L shape slot are designed to acceptable reflection coefficient that considered at S11 less than - 10 dB. According to the simulation and measurement result, the 10 dB reflection coefficient bandwidth is about 5.72 % and 7.3 % at both frequencies. The measured gain of the array is 3.65 at 2.4 GHz and 2.0 dB at 3.6 GHz. The agreement between simulation result and the measurement ones is good. The proposed antenna has increased the gain and reduces the reflection coefficient as well as increases the bandwidth of the antenna.

Application of Digital Signal Processing In Echo Cancellation: A Survey

The advanced communications world is worried talking more naturally by using hands free this help the human being to talk more confidently without holding any of the devices such as microphones or telephones. Acoustic echo cancellation and noise cancellers are quite interesting nowadays because they are required in many applications such as speakerphones and audio/video conferencing. This paper describes an alternative method of estimating signals corrupted by additive noise or interference. Acoustic echo cancellation problem was discussed out of different noise cancellation techniques by concerning different parameters with their comparative results .The results shown are using some specific algorithms.

Smart Le Tour checkpoint using RFID

A Smart Detector Database using Radio Frequency Identification (SDDR) is a cyclist tracking device. This device can be applied in the biggest race competition. Today, the monitoring system used unable to trace not arrive cyclist. As a solution, SDDR will detect cyclist that through the checkpoints and the profile about that cyclist would be displayed at the organizers PC monitor at the last point. The profile of each cyclist can be identified by using the information from database. The information from the Radio Frequency Identification (RFID) Database Handling System will be used by the organizer such as name, address, date and time of arriving at the each checkpoint. The main purpose of this device is to reduce the use of manpower at the each checkpoint. The aim of this project is to implement the RFID tags and readers as a detector. This project will use the Ultra High Frequency (UHF) RFID Reader that will be directly connected to the PC organizer without using the interface circuit. This system has been developed by using Microsoft Visual Basic (VB) that offered graphical user interface (GUI) for display the result. The database as well support for this system is Microsoft Access (MA).