R. Gowri

Rain fade mitigation using linear prediction technique in wireless communication

Proposed work shows the rain fade mitigation technique in wireless communication using linear prediction. Two year signal data from IPSTAR satellite at 20.2 GHz is used in this work. Proposed work can be used on different frequencies by using frequency scaling. Experimental signal is used to analyze original variations of the atmosphere. Delhi earth station data provided by SAC, Ahmadabad is used. The outcome of this work is very useful in short term signal behavior and rain fade mitigation technique to support power control in wireless communication.

Modeling of rain attenuation using equiprobability of rain fade and rain fall

Proposed work shows the modeling of rain attenuation. This modeling is based on rain rate versus rain attenuation characteristics by using equiprobability. Total three years data of signal and rain is used in this work. Data includes the information of received signal strength from IPSTAR satellite and rain fall data. Two year signal data at 20.2 GHz and two year rain data of corresponding period is used to develop rain attenuation model and one year data is used for validation. Delhi earth station data provided by SAC, Ahmedabad is used. The outcome of this work is very useful in short term signal behavior and rain fade mitigation technique to support uplink power control.

Long-Term Variability in Rain Attenuation Statistics over Indian Region

Proposed work shows the rain rate versus rain attenuation characteristics on the basis of equiprobability. Two year signal data from IPSTAR satellite at 20.2 GHz and two year rain data of corresponding period is used to develop rain attenuation characteristics. Delhi earth station data provided by SAC, Ahmedabad is used. The outcome of this work is very useful in short term signal behavior and rain fade mitigation technique to support uplink power control.

Various PSK modulation schemes for wireless communication

In this paper, various PSK Modulation schemes for wireless communication systems are designed and simulated using MIC techniques are presented. Three modulation schemes namely, Bipolar phase Keying (BPSK), Quadrature phase shift keying (QPSK), Eight-Phase-Shift Keying modulators (8-PSK) are designed at the S-band (2.4 GHz) that allows to achieve a very high accuracy in phase with very low power consumption. The configuration of the proposed PSK modulator is of parallel type, simulated using microstrip. The isolation between the carrier input port and the output port is very high and the phase error is the less than 2°. The substrate used for the PSK modulator is FR4 and the specification for substrate is dielectric thickness (h)=0.8mm, conductor thickness(t) = 0.035mm, dielectric constant(€)=4.4 and tangent loss=0.001.

Characterization of various coplanar waveguide discontinuities

The mathematical modeling and analysis of various CPW discontinuities are presented in this paper. Simulations of these discontinuities are done through ADS and its electrical equivalent parameters are evaluated through MATLAB programming (M-file) for open, short and GAP. And compared with closed form relations. Various discontinuities analyzed are open end, short, step, GAP, bend. The analysis is being done with reference to conventional CPW. The dispersive characteristics of these discontinuities are analyzed at 2.4, 5 and 8 GHz.

Analysis and Characterization of Edge Coupled Coplanar Waveguide Discontinuities for Filter Applications

This paper presents a technique for analysis and characterization of several types of edge coupled coplanar waveguide (ECCPW) discontinuities such as ECCPW open end-capacitive, ECCPW short circuit inductive and ECCPW symmetric stepped discontinuities in center conductor at elements at 30 GHz with coupling coefficient 17dB as microwave reactive elements. The topology assumes the fact that ECCPW coupled strip with small gap is equivalent to the center conductor strip of the CPW structure. The model element values de embedded for the measured S-parameters. The results show that ECCPW discontinuities can be used successfully as reactive elements for related applications. ECCPW are widely use in realizing band pass filters in communication circuit. Open end discontinuity shows the return loss (S11) of -0.282 dB, short circuit discontinuity gives the return loss(S11) of -0.010 dB and step discontinuity return loss (S11) of -12.9 dB and S12 of -17.667 dB with coupling coefficient of -17dB. Being simple and computationally efficient, the method is suitable to deal with extensive edge coupled CPW discontinuities problems. All discontinuities structure realizing on substrate 450-μm thick GaAs with dielectric constant 12.9.

Miniaturized Wilkinson power divider with harmonic suppression with stubs

This paper presents the comparative study of miniaturization of Wilkinson power divider along with higher harmonics suppressed. The circuit is designed at 2.4 GHz keeping in mind of wireless applications. Comparison is being made with respect to SWR, size, insertion loss with respect to the change in the length of the line. The miniaturization of the power divider is realized with capacitive loading which is being realized in the form of distributed element and not through lumped capacitor. Open circuited stub is being used for the capacitive loading. Reduction of transmission line segment from λ/4 to λ/12 is being analyzed with respect to SWR, insertion loss and percentage of bandwidth utilization. Power divider is realized on FR4 dielectric substrate (constant =4.5, height =1.5mm) and the simulations are performed using Genesys and ADS. The proposed power divider exhibits 40% size reduction, insertion loss not exceeding 0.7 dB and providing return loss better than +30 dB with the good isolation between the output ports and not reducing percentage of bandwidth utilization below 75.

Design of compact and high performance edge coupled coplanar waveguide band pass filter

This paper present new technique for designing the compact and high performance edge coupled coplanar waveguide band pass filter (ECCPW-BPF) at the operating frequency 30 GHz. The simulated results show good agreement with low pass band insertion loss approximate-3dB and high return loss (greater than 10 dB). The design edge coupled coplanar waveguide band pass filter (ECCPW-BPF) has 10% bandwidth at a centre frequency of 30 GHz. These filter exhibit attractive characteristics in term of miniaturization, return loss, insertion loss, selectivity, and the suppression of spurious frequency bands. The characteristics show that design filter is very useful for applications in the wireless communication systems.

High performance microstrip antenna arrays for mobile adhoc network

This paper presents a 2×2 planar array with high gain and less area as compared to 1×4 linear array suitable for the application of MANET (Mobile adhoc network). The antenna arrays consist of four triangular patch antenna elements designed on RT/Duroid substrate and the resonant frequency of these antennas is 1.29 GHz. The designed antennas provide the reflection coefficient below -18 dB. The gain of 2×2 planar array is found about 13 dB and the area is 94732 mm2 whereas 1×4 linear array provide the gain about 12 dB and the area is 97671 mm2.

Circularly Polarized Antenna Array for L-Band Applications

The design of antenna array in the wireless communication system can be used to achieve high gain, steering capability and also to reduce the effect of fading. These antenna array is suitable for L-band applications such as military, global positioning system, digital audio broadcasting and other telecommunication areas. This paper presents a simple, low cost, low profile triangular micro strip antenna array with circular polarization providing high gain by 4×1 array. The designed antenna array provide the return loss below-20 dB and the gain of this antenna array is found to be around 12 dB. The resonant frequency of this antenna array is 1.29 GHz. Single triangular micro strip patch is resonating at 1.29 GHz and quarter wave transformer with power division method is used for matching the loss due to reflection. Single patch is providing the gain of 6.31dB.