Statistics of rainfall rate at 60 minutes integration time in Malaysia

Background: This paper presents the statistics of rainfall at 60- minute integration time in Malaysia for the period of 12 months from January to December 2009. Objective: To analyze the statistics and characteristics of rainfall intensity measurement at KLIA, Malaysia. To study the behavior of measured rainfall intensity and represent the annual distribution of the measured rainfall through cumulative distribution functions together with different types of rainfall that occurred in 2009. Results: The results obtained show the cumulative distribution functions and amount of the rainfall rate for that particular year. The results also show the different cumulative distribution functions for four different rainfall types that occur in 2009. Conclusion: The study of the 12-month tipping bucket data has given the characteristics of the collected rainfall. From the results obtained, it shows that Malaysia is within equatorial region with the characteristics of two distinguishable rainfall rates that occurs during the whole year

Design of dual-linearly polarized patch antenna at millimetrewaves

Phased array antenna capable of providing wider scanning range of beam radiation. The conventional phased array antenna mostly covered a single polarization of beam radiation. Therefore, by improving the phased array antenna design by implementing dual polarization will enhance the capacity of beam radiation to radiate at wide angular angle. A dual linearly polarized phased array antenna slanted at ±45° has been designed to operate at frequency of 28 GHz by using CST tool. Based on the simulation performance, the reflection coefficient (S11) and radiation pattern of both single and array antenna shows a good performance. The S11 value for both single and array antenna are -11.36 dB, and -20.17 dB, respectively. The gain of single slanted -45°, single slanted +45°, and 1x2 ±45° array patch antenna are 7.48 dB, 7.47 dB, and 7.08 dB

Assessment of radar reflectivity-rainfall rate, Z-R relationships for a convective event in Malaysia

Abstract— Various relationships between radar reflectivity Z and rainfall rate R commonly identified as Z-R relationships have been derived in order to provide better accuracy for rainfall rate estimation using weather radar. It is critical for the air traffic management at the airport to accurately detect existence of potential microburst and wind shear. There are numerous factors that can certainly affect the accuracy of Z-R relationships including poor hardware calibration. However, the inaccuracy of Z-R relationships also might be due to the differences between the precipitation at the ground level and the precipitation aloft because radar does not scan all the way down except at close range. Several Z-R relationships had also been proposed in the attempt to achieve better accuracy for rainfall estimates by radar system in the tropical region. Nonetheless, the most accurate Z-R relationship for Malaysia weather radar is yet to be investigated and to be identified within the study period. This paper presents the preliminary analyses of previously proposed Z-R relationships for Malaysia weather using new radar data and ground rainfall rate. Comparisons were made between values obtained from the previously proposed relationships for radar and the ground truth measurements. It was identified that the previously proposed relationships estimations are significantly lower than the rain gauge data

Initial assessment of radar reflectivity-rainfall rate, Z-R relationships for moderate rain events in Malaysia

and rainfall rate (R), identified as Z-R relationships have been derived to facilitate the rainfall rate estimation by weather radar. Most of the previously proposed Z-R relationships were implied as too generalized and only applicable within the region that has identical climate characteristics or behavior. Based on such notion, the most accurate Z-R relationship applicable for Malaysian weather radar therefore needs to be investigated and identified. In this paper, two renowned models will be evaluated on how well they fit to Malaysian weather radar data. Preliminary comparisons between the previously proposed Z-R relationships using newly acquired radar data in Malaysia and ground-based rain gauge measurements are also presented. The use of inaccurate relationship can cause error in radar rainfall estimates. This might pose unacceptable risk for the aviation industry where accurate, dependable weather information deduced by radar system is expected at all times

Impact of outdated CQI report on adapted well-known packet scheduling algorithm when streaming video

Given that there are overgrowing demands for video streaming application in the downlink Long Term Evolution Advanced (LTE-A), effective scheduling of these delay-sensitive real-time packets are critical. However, there remains a challenge where (re)transmission of video packets in the downlink LTE-A may subject to numerous impairments including outdated Channel Quality Information (CQI) report. This paper studies the impact of outdated CQI on the adapted Maximum-Largest Weighted Delay First Performance (M-LWDF) namely Adapted M-LWDF1 (AM1) and Adapted M-LWDF2 (AM2) algorithms. Note that the AM1 algorithm chooses a user first then (re)transmit packets to the selected user on the best mobile cellular channels whereas scheduling decision in AM2 algorithm is made on per mobile cellular channel basis. Simulation results demonstrate the robustness of the AM2 algorithm in minimizing the detrimental effects due to outdated CQI report when streaming vide

Rain induced scintillation measurement on satellite link in tropical climate

Attenuation time series were collected to study the rain induced scintillation during September 2011 – August 2012 from MEASAT3 satellite operating at Ku-band. In this paper, scintillation statistics are analyzed in rainy condition extracted manually from 188 rainy events. The scintillation distributions are represented scintillation intensity and amplitude by monthly, seasonal, worst-month and annual distributions. Probability density function (PDF) of scintillation intensity correspondingly agrees to Generalize Extreme Value (GEV) fit. In addition, model validation to the measured data is also provided

Experimental Solid State Physics on f- electron Systems(Annual Report (from April 1997 to March 1998))

Satellite communication systems a superior capacity. Millimeter wave offers a allocation, involves small-sized antenna experiences less congested spectrum enviro rain posses a crucial intimidation to such satell links especially in tropical region where the severely affect the signal. Rain is the factor that the implementation of higher frequency communications in this region. Time diversity plausible mitigation technique to coun impairments. It is envisioned that the tech requiring extensive auxiliary’s equipment. Th the likely improvement of a future Ka-band Earth link using proposed time diversity ( tropical regions. The analyses relating to prediction of a satellite communication link assimilating TD scheme are also included. The and its associated equations were determin memory capacity requirement of TD. The integrated accordingly at the receiver with attenuation due to rain endured by the propag Index Terms— fade mitigation techniqu tropical regions, satellite communication

Design of Hybrid Koch-Minkowski fractal dipole antenna for dual band wireless applications

— In many wireless applications, antenna comes with variable sizes. The interest for small and compact antennas in wireless applications is increasing due to the mobility of the wireless devices. Internet of Things (IoT) defined as a network of small, low cost, low power, ubiquitous electronic devices. It is expected that WiFi proves to be one of the solutions for IoT technology. WiFi Alliance has introduced an unlicensed band of 900 MHz (HaLow) in 2017 to support IoT which requires low power, high data rate and long range. Hence, the demand for small antennas is substantial especially due to the booming industry in mobile communication. Generally, an antenna at low frequency exhibits large size of antenna. This paper presents the design of fractal dipole antennas for dual band wireless applications. The designs are based on hybrid Koch-Minkowski fractal method for the benefits of miniaturization. The antenna designs have been simulated using CST Microwave Studio and fabricated using Rogers 5880 substrate. Based on the results, it is observed that the fractal antennas are able to operate at dual frequencies, at 900 MHz and 2.6 GHz with return loss of 18dB and 16 dB respectively. The small size, thin and lightweight of antenna design (115 mm x 22.5 mm x 0.285 mm) makes it an attractive feature for compact wireless applications

Design of circular patch antennas at mmWave

Recently, the increasing demands of 5G of higher data rates, and lower latency have been progressively investigated to cater the modernization and technology development. In order to achieve higher data rates, it is important to improve the bandwidth as well its gain. The antenna performance is crucial to determine the achievable bandwidth and gain. One of the parameters that influence the antenna performance is the thickness of the substrate. In this paper, a circular patch antenna is designed by using Rogers RT5880 of dielectric constant 2.2, and loss tangent 0.0009. The substrate thickness has been varied in order to investigate its effect to antenna performance i.e. return loss. The substrate thickness that has been investigated are 0.127 mm, 0.381 mm, 0.508 mm, 0.787 mm, and 1.575 mm, which are the standard thickness of Rogers RT5880. The simulation works are performed by CST Microwave Studio. The tasks are divided into two parts; i) the different substrates thickness are investigated while other parameters remain constant and ii) the radius of the circular patch of the antennas have been optimized in order to achieve the resonance frequency at 28 GHz based on the abovementioned substrate thickness used. The performance of the antenna is described in terms of its return loss, bandwidth, and gain. In (i), the results show that as the substrate thickness increases, the resonant frequency decreases under conditions of other fixed parameters value. The highest bandwidth is 1.17 GHz for substrate thickness of 0.508 mm while the highest gain is 7.52 dB for substrate thickness of 0.381 mm. For (ii), the highest bandwidth is 1.37 GHz for substrate thickness of 0.508 mm meanwhile the highest gain is 7.56 dB for substrate thickness of 0.381 mm at the resonant frequency of 28GHz

A wideband circularly-polarized spiral antenna for Cube Sat Application

In this paper, a wideband circularly-polarized spiral antenna is proposed to be used for CubeSat application. The antenna covers two of CubeSat frequencies; the S-band (2.2 GHz) and X-band (8 GHz). The proposed antenna belongs to the wideband and frequency-independent antenna category, which are known to provide a constant radiation pattern, impedance and polarization throughout the whole bandwidth. The performance of the spiral is compared in two different conditions; in free space and above a ground plane with a separation distance of λ/4 at the operating frequency of 2.2 GHz and 8 GHz. The spiral above the ground plane exhibits a unidirectional radiation and higher gain with an increase of 26.6% (2.2 GHz) to 34.6% (8 GHz) than the free space spiral. Moreover, the return loss also managed to stay within the ideal limit of S11<-10dB (-19.528 dB at 2.2 GHz, and -21.92 dB at 8 GHz) and exhibits circularly-polarized radiation with low axial ratio < 3 dB (0.78 dB at 2.2 GHz, and 0.89 dB at 8 GHz)