Mimi Aminah Wan Nordin

Bandwidth enhancement of a compact antenna based on the composite right/left-handed (CRLH) Transmission-Line (TL)

A new composite right/left-handed (CRLH) metametrial antenna with wide bandwidth is presented. Enhancement to the bandwidth of the structure was achieved by incorporating parallel plate between the vias and the ground planes. The plates serve to reduce the shunt capacitance of the structure. The proposed antenna is a tri-band and its length, width and height at the first resonant frequency are lambda0/26, lambda0/26 and lambda0/27, respectively; where, lambda0 is the free space wavelength.

Design and Optimization of Dual Band Microstip Patch Antenna Using Slots Pair

In the recent communication engineering, communication links require antennas which can operate more than one application band. Multiband antennas with microstrip patch are designed basically for mobile and aerospace applications, the reasons for that is that these antennas have very light weight, low profile and low power consumption. These antennas have many shapes to get the bandwidth and the gain required. This paper attempts to design Microstrip Patch Antenna to facilitate dual band operation using multiband design formula proposed in literature. Two frequencies of 1.8 and 2.4 GHz were designed for mobile and wireless LAN applications. Antenna has been designed and optimized using computer simulation technology CST electromagnetic simulator. Desired dual band has been achieved by very simple geometry of pair of slots. Pair of slots antenna has been fabricated and tested using vector network analyzer (VNA) in the Lab. Test result is found very good agreement with simulated result.

Assessment of Statistical and Empirical Conversion Methods of Integration Time for Rainfall Rate in Malaysia

This paper presents some preliminary observations of assessments regarding the precipitation intensity conversion methods from 60- to 1-min integration time. There are two conversion methods were identified and used for this findings; Rice-Holmberg and Khairolanuar et al. conversion methods. Different type of precipitation were analyzed and implemented in analytical method of Rice-Holmberg and characteristics of rainfall rate distributions were evaluated from the empirical method of Khairolanuar et al. Rainfall intensity data were acquired from Malaysia Meteorological Department (MMD). The rainfall rate data consist of twelve consecutive months from January to December 2009. The evaluations for the acquired data were carried out to produce annual rainfall rate cumulative distribution and as well as its cumulative distribution at 1-min integration time utilizing the aforementioned conversion methods. The comparisons of the performance of these two methods were also examined. Based on the evaluation, it can be observed that Rice-Holmberg and Khairolanuar et al. produced percentage errors around 19 % as compared to ITU-R P.837 at 0.01 % of time exceedance.

Comparison of Conversion Methods from 60- to 1-min Integration Time for Rainfall in Malaysia

This paper presents some preliminary assessments of the precipitation rate conversion methods from 60-min to 1-min integration time. The conversion methods used in this study are Moupfouma and Khairolanuar et al., and ITU-R P.837. Rainfall rate data of twelve-months duration from January to December 2009 were acquired from Malaysia Meteorological Department (MMD) and exploited for the evaluation. The rainfall data were collected from MMD rain gauge station located at Kuala Lumpur International Airport (KLIA). The investigations comprise of producing annual rainfall rate cumulative distributions of the measured data. The equivalent 1-min annual rainfall rate cumulative distributions using conversion methods as mentioned above. Predicted values of annual 1-min cumulative distribution established by ITU-R P.837 are used as references. The equivalent 1-min equivalent cumulative distribution obtained from Moupfouma’s and Khairolanuar et al.’s methods are then compared with that of ITU-R P.837 to validate the applicability and efficiency of each method. According to the results, it can be observed that Khairolanuar et al.’s method capable of generating equivalent 1-min rainfall values with smallest percentage difference as compared to ITU-R P.837 at 0.01 % of time exceedance.

Classification of Precipitation Types Detected in Malaysia

The occurrences of precipitation, also commonly known as rain, in the form of “convective” and “stratiform” have been identified to exist worldwide. In this study, radar return echo or known as reflectivity have been exploited in the process of classifying the type of rain endured. The Malaysian meteorology radar data is used in this investigation. It is possible to discriminate the types of rain experienced in such tropical environment by observing the vertical characteristics of the rain structure. Heavy rain in tropical region profoundly affect microwave and milimetre wave signals, causing interference on transmission and signal fading. Required fade margin for wireless system largely depends on the type of rain. Information relating to the two most prevalent types of rain are critical for the system engineers and researchers in their endeavour to improve the reliability of communication links. This paper highlights the quantification of percentage occurrences over 1 year period of 2009.

Fade Margin Estimation Technique Using Radar Data for Satellite Link

The fade margin is an important parameter used by the operator to measure the link availability for a given time. Fade margin is a parameter that is used in the design of satellite links to ensure optimal performance of the link. A new technique is proposed where the fade margin of a satellite link can be estimated using attenuation statistics of radar data. Data set acquired from Malaysian meteorological radar for the year 2009 is used in the study. Radar return or reflectivity is used in the process of generating the attenuation values. The reflectivity is first converted into rainfall rate value and the specific attenuation is then calculated. The rain attenuation values can be derived by the multiplication of the specific attenuation and the path length affected. The rainfall rate derived from radar information is used in calculating the slant path attenuation of the satellite link. The databases of rain attenuation is then compiled with the time duration to acquire the cumulative distribution function (CDF) for the specified link. The satellite link investigated are based on the RazakSAT link in relation to its ground station located at Sg Lang, Banting, Selangor, Malaysia for X-band and MEASAT-3 satellite in relation to its ground station at Cyberjaya, Selangor, Malaysia for Ku-band.