J. S. Mandeep

Rain attenuation predictions at ku-band in South East Asia countries

The rain attenuation in the 12-GHz band and one-minute- rain rate were measured at four satellite beacons located in South East Asia countries over a three-year period (2002-2004). The cumulative distribution of rain rate obtained as well as cumulative distribution of rain attenuation obtained are presented and compared with the rain prediction models. Most of the rain prediction models showed noticeable deviation to the measured values above the existence of the breakpoint (the point at which the slope changes). The results can be employed to guide the design and application of slant-path communication systems, especially in South East Asia countries.

Microstrip bandpass filter at S band using capacitive coupled resonator

A microstrip bandpass filter with a new type of capacitive coupled resonator is presented. The filter is designed to be smaller compared to the same type of parallel-coupled bandpass filter. The filter is designed for a centre frequency of 2.5 GHz that lies in the S-band frequency range. The insertion loss at fo is 2.4 dB and the measured 3 dB bandwidth is 8.6%. The agreement between the predicted and measured results is excellent, and even the circuit simulator gives a very good prediction for the filter characteristics.

Equatorial Rainfall Measurement on Ku-Band Satellite Communication Downlink

Communication systems operating at frequencies above 10 GHz in equatorial climates are subjected to many fade occurrences due to heavy rain. Rain rate analysis using 1-minute data for 10 years (1996–2006) measurements in Penang shows that the rain exceeded 126.8 mm/h for 0.01% of a year (R0.01). Simultaneous measurements of Ku-band rain attenuation give A0.01 as 22 dB. The rain rate and attenuation are characterized by the presence of breakpoints in the respective exceedance curves. The attenuation exceeds the fade margin for about 8.8 hours in a year.

Design of cartesian feedback RF power amplifier for L-band frequency range

A phase-alignment system is used fully integrate a power amplifier, Cartesian feedback linearization circuitry, and a phasealignment system. The phase-alignment system employs a new technique for offset-free analog multiplication that enables it to function without manual trimming. This paper demonstrates how the phase-alignment system improves the stability margins of the fully integrated Cartesian feedback system. The power amplifier itself, integrated on the same die, operates at 1 GHz and delivers a maximum of 30 dBm of output power into a 50-load. The class AB design for open loop and close loop power amplifier with Cartesian feedback, demonstrated a good linearity of 50 dBc and 80 dBc, respectively. The operating power is 2 W at 1000 MHz frequency.

DESIGN OF A DUAL MONOPOLE ANTENNA WITH WIDEBAND FREQUENCY

In this article, a design for wideband dual-frequency folded dual monopole antenna is presented. By the proper choice of the dimensions of the Y-shape patch and the gap distance for the feeding structure, an additional resonant mode and wide impedance matching can be realized. Both simulated and experimental results, such as antenna impedance bandwidth, antenna radiation characteristic, and antenna gain have been presented and discussed. The lower impedance bandwidth covers from 8.78 GHz to 9.05 GHz, and the upper impedance bandwidth covers from 11.64 GHz to 12.01 GHz.

Case Study of the Rain Attenuation at Ka Band

This paper presents one year rain rate intensity and rain attenuation at Universiti Sains Malaysia (USM). Communication systems operating at frequencies above 10 GHz in equatorial climates are subjected to many fade occurrences due to heavy rain. Measurement of rain attenuation at Ku-band will be used to estimate the rain attenuation at Ka-band. The Ramachandran and Kumar model was used to calculate rain attenuation at Ka-band. Rain rate analysis using 1-minute data measurement at USM shows that the rain rate exceeded 110 mm/h for 0.01% of a year (R 0.01). Simultaneous rain attenuation (A 0.01) at Ku-band was at 18 dB and by using the predicted model, the rain attenuation at Ka-band was found to be 30 dB at 0.01% of time rain attenuation exceeded.

Statistics of annual and diurnal cloud attenuation over equatorial climate

At frequencies above 10 GHz, cloud attenuation in equatorial climate is one of the components that need to be characterised for low-availability satellite links. In addition to annual and worst month cumulative cloud attenuation, the statistics of seasonal and diurnal variations are required for providing detailed insights into system design. The authors present the cloud occurrences observed during different months, seasons and cloud attenuation results obtained from Penang, Malaysia, for a period of 5 years. A comparison of the present results with the results obtained from the existing models is also presented.

Tropospheric Scintillation Measurement in Malaysia at KU-band

This paper compares the predicted monthly scintillation means of nine scintillation prediction models to the monthly mean of the empirical data collected from the beacon receiver located at USM which has a frequency of 12.255 GHz and elevation angle of 40.1°. The impact of tropospheric scintillation has to be considered in the design and planning of satellite communication systems at frequencies above 10 GHz.

Worst Month Rain Statistics Measurement in Malaysia

Excess attenuation due to rainfall is one of the most important constraints to the performance of microwave radio links. In temperate climates at frequencies above 10 GHz, rainfall rates have significant effects on the performance of microwave radio links. Therefore the behavior of radio communication links varies seasonally over a year. This paper presents on the results obtained from the analysis of 3 years rainfall rate and attenuation measurements that were carried out in Universiti Sains Malaysia (USM). The collected data were used to derive the average worst month statistics and its relationship with the average annual distribution. This relationship was found to be suitable with the one proposed by ITU. Therefore the average 3 years of the worst month data provides further support to usefulness of the ITU worst month model.

Investigation of microwave properties of high permittivity ceramic substrate

The study of new compositions of high permittivity dielectric materials at microwave frequency is proposed in this paper. New types of dielectric materials will be developed, measured and implemented into working electrical microwave models with the help of microwave simulation software. After fabrication, the performance and characteristics of these materials will be studied and a comparison will be made in order to find the most effective material and design for use in real world microwave devices and designs. A simple dielectric resonator structure will then be developed to simulate the use of the new dielectric material in future microwave applications.