Comparative studies of the rain attenuation predictions for tropical regions

The radio waves propagating through the earth atmosphere will be attenuated due to the presence of atmosphere particles, such as water vapor, water drops and the ice particles. Meanwhile, the atmospheric gases and rain will both absorb and scatter the radio waves, and consequently degrade the performance of the link. The results of various studies conducted in temperate and tropical regions have been published in research papers. This paper presents the summary of comparative studies on different rain attenuation prediction methods for terrestrial microwave links tropical regions. Basically the models described in this paper include those of the ITU-R, revised Moupfouma, revised Silva Mello and Lin model. The objective of this study is to reveal the most suitable rain attenuation prediction model for the Malaysian tropical region. This paper will provide useful information for microwave engineers and researchers in making decision over the choice of most suitable rain attenuation prediction for terrestrial links operating in a tropical region. Even though the ITU-R model underestimates the rain attenuation at higher frequencies, the test results have clearly indicated that it is most suitable for predicting terrestrial rain attenuation in tropical Malaysia, compared to others

A multi band mini printed omni directional antenna with v-shaped for RFID applications

This paper presents a mini multi-band printed omni-directional antenna with v-shaped structure for radio frequency identification (RFID) applications. The proposed multi-band antenna is developed from the initial v-shaped design which is only capable of working as a single-band antenna. By deploying a concept of dipole antenna to an initial design, the proposed antenna is accomplished to operate with two different modes of RFID system which are passive and active modes at frequencies of 915MHz and 2.45 GHz respectively. The passive RFID tag is invented when a chip of Ultra High Frequency (UHF) is integrated with a proposed multi-band antenna. This passive tag, which is able to radiate with the measured signal strength, shows that the reading ranges are boosted almost two times compared to the conventional inlay antenna. The maximum reading range of passive RFID tag with inlay antenna is 5 m, though a reading range up to 10m is achievable through the deployment of the proposed antenna at a measurement field. Implicitly, the measurements carried out on the antenna are in good agreement with the simulated values. Moreover, the size of the mobile passive RFID tag has been substantially as 100mm × 70 mm, even though the antenna is fabricated with an inexpensive FR-4 substrate material. With the reasonable gain, coupled with cheaper material and smaller size, the proposed antenna has attractive potentials for use in RFID applications with multiple frequency antenna for active and passive tags

Development of RFID EPC Gen2 Tag for Multi Access Control System

A Radio Frequency Identification (RFID) use radio waves to identify an object, this technology become useful for the future because of the advantages. Access system using RFID card is commonly used in a building, parking area, housing complex, etc. This paper explore and develop the use of RFID EPC Class1 Gen2 tag for multipurpose access system for   identification and access control, such as personal identity identification, door access control and gate entry permit or access control. With the same tag Identity (ID) user can access many areas. RFID EPC Class1 Gen2 tag working at UHF band 902-928 MHz, this type of tag more suitable for multi access control because of scaterring technique in reading for the tag, as for gate access need longer distance read range. All users ID and information stored at the one central database, every transaction at the controlled were recorded in a control system.DOI:http://dx.doi.org/10.11591/ijece.v3i6.385

Miniaturize size of dual band branch-line coupler by implementing reduced series arm of coupler with stub loaded

An extremely reduced size branch-line coupler operating at dual frequencies of WLAN band 2.45 GHz and 5.8 GHz is presented which is 58% smaller compared to the conventional design. The technique presented introduces the combination method in which the length of series lines is half than the length of shunt branch lines and the loading of stub tapped to the center of the series branch line that forms the couplers arms. Furthermore, the coupler accurately divides the input signal by two parts with the same power and 90° phase difference. Also, the reflection coefficient and the isolation are as good as conventional one. The agreement of the measurement and simulated confirms the theory and validates the proposed coupler design. The measurement shows 33.83% and 9.22% bandwidth for the lower and upper frequency, respectively

Switched Beam Smart Antenna for Wireless Local Area Network

In wireless communication system, interference is one of the issue facing that can disturb in communicating between base station and mobile devices. This paper propose switched beam smart antenna system, an octagonal configuration of directional antenna is introduced and selecting beam to desire user. Each beam of antenna covered 45 degrees; by assembly of all directional antennas to create an omni-directional configuration with coverage all the beam 360 degrees. To control of the beam switching, an inexpensive microcontroller PIC 16F877 from microchip used, radio signal strength of mobile device receive as reference signal and compare to each of beam, the highest signal received is selected than microcontroller will lock to the desire beam. A few samples of received signal strength to be analysis by an algorithm to avoid multiple signals and select actual signal strength received. In this experiment 2.45 GHz ISM band used for the transmitter and receiver and testing have been conducted in outdoor environment. Results shows that switched beam smart antenna working fine base on mobile device location and able to switch the beam while mobile device is moving

Performance Analysis of Microstrip Grid Array Antenna on Different Substrates for 5G Mobile Communication

This paper investigated the performance and characteristics of microstrip grid array antenna (MGAA) on three different substrates which are Rogers RT5880LZ, Taconic RF-43, and Fr-4. For this work, the proposed MGAA has been designed at 15 GHz for 5G mobile communication application. The proposed microstrip grid array antenna consists of 12 cells block with 19 radiating elements and was feed using the 50 Ω coaxial port from the ground plane. A comprehensive study on the effect of substrate on the performance of MGAA is carried out. S-parameters, gain, and efficiency of MGAA on all those substrates have been used as parameters in determining the performance of proposed antenna in order to fulfill the design criteria for 5G mobile communication application. The design and simulation process of MGAA was done in CST Microwave Studio Softwar

A novel green antenna phase-shift system with data acquisition boards

A novel green phase shifter system is proposed in this research. The system is developed by a combination of reconfigurable beam steering antennas and data acquisition (DAQ) boards. A combination of two reconfigurable beam steering antennas, located side-by-side, forms a spatial configuration structure with a fabricated ‘green’ element plank of rice husk placed in between. The concept of a spatial configuration technique has been ‘mutated’ by shifting the structure of spiral feed line and aperture slots of first beam steering antenna by as much as 45 ◦ . The PIN diode switches connected to the DAQ boards enable the intelligent capability of the spatial antennas. The activation of certain degree radiation patterns of either the first beam steering antenna or the second beam steering antenna depends on the memory of the DAQ boards — Beam Manager. When an intruder comes from the cardinal angles of 0◦/ 360◦, 90◦, 180◦, or 270◦, its range and angles’ location will be automatically detected by the first antenna through the output ports of the 1st DAQ: P1.0, P1.1, P1.2, and P1.3. The second antenna is then activated by the output ports of the 2nd DAQ: P2.0 up to P2.3, to adaptively maneuver the beam towards four different ordinal directions of 45◦, 135◦, 225◦, and 315◦

Interference coupling loss between highaltitude platform gateway and fixed satellite service earth station at 5850-7075 MHz

High Altitude Platform Station (HAPS) is a new type of communications station that is expected to operate in parallel with terrestrial and satellite systems. Under agenda item 1.20 of next World Radio Conference 2012 (WRC-12), a new spectrum allocation for HAPS gateway link is proposed in the frequency band 5850-7075 MHz. Although the proposed band will provide reliable communication, the band is already saturated by the allocations of Fixed Satellite Service (FSS) earth station transmissions that have signal levels much higher than those in HAPS systems. Besides, the current HAPS spectrum sharing regulation method has limitations, such as coordination using separation distance as a dominant factor, ignoring the frequency isolation effects, and implementing Free Space Loss (FSL) model as a default propagation mechanism; thus, pessimistic results lead to large separation distances. To illuminate HAPS' chance for spectrum sharing with existing services, this paper proposes a new spectrum-sharing prediction method using the spectral technique of Net Filter Discrimination (NFD) along with the antenna height within a deployment area. Reduction in required physical isolation is achieved, and frequency isolation produces an Interference Coupling Loss (ICL) that can utilize the radio spectrum resource as efficiently as possible

Microwave signal attenuation over terrestrial link at 26 GHz in Malaysia

The effect of rain on the microwave systems is more critical especially for countries located in tropical and equatorial region that experience high rainfall rate throughout the year. In order to predict a reliable and an accurate rain prediction model, it is required to determine the one-minute integration time of rainfall rate together with direct measurement of rain attenuation. In order to counter the current trend of employing higher frequencies especially in tropical and equatorial regions, there is an urgent need to carry out studies related to the effect of rain in order to get a better rain attenuation prediction model. Therefore, the purpose of this study is to investigate the effect of rain on terrestrial microwave system operating at 26 GHz in Malaysia. The rain intensity with one minute integration time is measured at Universiti Teknologi Malaysia-Skudai (UTM-Skudai) and 99 rain gauges located throughout the Peninsular Malaysia. This study explains the detailed experimental set up and analyses of both rain rate and rain attenuation measurements. The analysis on large-scale study area includes the comparisons between the measured rainfall data and the Drainage and Irrigation Department (DID) rainfall data and also with the Malaysia Meteorological Services (MMS) rainfall data. This study has successfully proposed a new rain rate and rain attenuation prediction model and the obtained results show satisfactory performance and good agreement