Anup Kumar Gogoi

Super wideband antenna with single band suppression

In this paper, a band-notched compact printed monopole super wideband (SWB) antenna has been designed and fabricated. The SWB antenna composed of a radiating patch with a 50 V triangular tapered feed line which is connected through a feed region, and a chamfered ground plane (CGP), that covers the frequency band from 0.9–100 GHz (ratio bandwidth of 111.1:1) with a reflection coefficient |S11| , 210 dB, except in the notched band of 4.7–6 GHz for Wireless local area network IEEE 802.11a and HIPERLAN/2 WLAN band. To realize the band notch characteristics a C-shape parasitic element is employed near the CGP etched with two symmetrical L-slots and placed under the radiating patch. Proposed antenna structure occupies a relatively small space (30 × 40 × 0.787 mm) and achieved much wider impedance bandwidth as well as higher gain compared with the existing ultra wideband and SWB antennas.

Few More Quasi-Orthogonal Space-Time Block Codes for Four Transmit Antennas

In this paper, we derive few new quasi-orthogonal space-time block codes for four transmit antennas. These codes differ from each other and existing codes in character matrices and/or correlated values in character matrices. These codes can be constructed using elementary sub-matrices. We also derive corresponding maximum-likelihood decoders for the proposed codes. We observe that decoding complexity of some of these codes is less as compared to the rest of them for rectangular-QAM modulation. Bit error rate performance of these codes have been shown to be same as those of existing quasi-orthogonal space time block codes for four transmit antennas over quasi-static flat Rayleigh fading channels.

Subtractive clustering of vertices for CPCA based animation geometry compression

In the Clustered PCA(CPCA) algorithm for compressing the animation geometry sequences, the vertex trajectories are clustered using the K-means algorithm followed by the Principal Component Analysis(PCA) of the clusters. However, the compression performance of the method is constrained by the initial random selection of the cluster centres. This paper presents a stable method for initializing the cluster centres by the subtractive clustering technique prior to the application of the K-means algorithm. Simulation results on some test animation sequences show better performance of the CPCA with the proposed initialization compared to the CPCA with random initialization.

Design Issues of Piezoresistive MEMS Accelerometer for an Application Specific Medical Diagnostic System

ABSTRACT This paper reports the design and simulation of finite element method (FEM)-based micro-electro-mechanical-systems (MEMS) piezoresistive accelerometer used in a strapdown medical diagnostic system. A square proofmass with four flexures is used in this design. Here, p-doped single-crystal silicon are used as eight piezoresistors implanted on the flexures for sensing the maximum stress; and they are connected in the form of a wheatstone bridge with each arm containing two piezoresistors. Basically, here two different geometric configuration but of same material have been designed and simulated using FEM-based tool for dynamic range (±)2g. To assure better performance characteristics, different analysis for both the configurations are done. Configuration 1 is found to have better performance with respect to load withstanding capability, eigen value analysis, better response characteristic, and low cross-axis sensitivity. Furthermore, the measurement scheme adopted is the wheatstone bridge, which gives better performance as offset is almost nullified.

MPPT of solar photovoltaic cell using perturb & observe and fuzzy logic controller algorithm for buck-boost DC-DC converter

Solar Photovoltaic (PV) power keeps changing with solar insolation(S) and ambient temperature (T) because PV cell exhibits non-linear current-voltage characteristic. So the Maximum Power Point (MPP) varies with the changing S and T. However with the advancement of power electronics converter technology, it is now possible to operate the PV power at its MPP in order to improve the overall efficiency. This paper presents maximum power point tracking (MPPT) based on Perturb & Observe (P&O) and Fuzzy Logic Controller (FLC) for PV with dc-dc buck boost converter for the purpose of performance evaluation and comparison analysis thereof. Both the algorithms were simulated in MATLAB-Simulink with 100W PV module (Solar Alpex Panel 1552P-3613G-166109) connected to buck-boost dc-dc converter. The results of simulation and analysis indicate that the proposed FLC algorithms provide better MPP than that of conventional P&O method. FLC algorithms significantly improve the efficiency of MPPT and provides faster responses particularly during fast changing environmental conditions besides the fact that it is simple and can be implemented with PIC Microcontroller or FPGA.

A novel super wideband notched printed trapezoidal monopole antenna with triangular tapered feedline

A novel ultra broadband planar monopole antenna with band notch characteristics is presented. An ultra broadband of 3.1 GHz-94.7 GHz (31:1) is achieved. Improved designs are used for microstrip feed line, feed region of the antenna and radiating element to obtain ultra broadband characteristics. A triangular tapered microstrip feed line is used, nearly optimal taper or curve is employed in the feed region and the ground plane feed gap is optimized to 1.4 mm. The radiating element isa trapezoidal patch. The overall dimensions of the antenna are 40×30×1.6mm3. Band notch characteristics in WLAN operating region is achieved by placing a U-shaped slot in radiating patch. The peak of notch characteristics occurs at 5.55 GHz in 4.85 GHz-5.85 GHz rejection band. Moreover, good omni-directional radiation pattern, approximately constant peak gain and better efficiency is observed. A simple design for ultra broad bandwidth adds merit to this antenna. This antenna can be used for ultra wideband (UWB) and super wideband (SWB) applications.

Design and analysis of FEM based MEMS accelerometer for detection of postural tremor in Thyrotoxicosis

This paper reports the design and simulation of FEM based MEMS piezoresistive accelerometer used in a strap-down inertial measurement unit (IMU) for detection of postural tremor in Thyrotoxicosis. A square proofmass with four flexures is used in this design. Eight piezoresistors are implanted for sensing the maximum stress and they are connected in the form of a wheatstone bridge with each arm containing two piezoresistors. This type of arrangement minimizes cross axis sensitivity and provides a sensitivity of 6.2mV/g; the dynamic range being (±)2g. MEMS structure has been designed and simulated using FEM based multiphysics software COMSOL 4.3 and the entire IMU unit consist of the accelerometer and associated signal conditioning unit.

Performance of a coherent BPSK receiver in an impulsive noise environment

The performance of a digital communication system in the ELF/VLF range operating in situations like a mine environment is strongly affected by atmospheric noise which has an impulsive component on a white Gaussian background. We analyze the bit-error-rate performance of a coherent BPSK receiver subject to such noise.

Regressive linear prediction with doublet for speech signals

In this paper we proposed a new line prediction algorithm, Regressive Linear Prediction with Doublet (RLPD) for speech signals. Unlike conventional Linear Programming (LP), nth sample of signal x(n) is predicted based on p + 2 previous samples by forming p regression lines. Each line is formed by using two alternative samples from p + 2 samples. As a result, the obtained all pole filter is able to perform better than conventional counterpart for small p. RLPD predictor is obtained by minimizing square of the prediction error. The experiment show that the performance of the RLPD method is effective compared to the LP method for the voiced speech signals corrupted with additive white gaussian noise.

Design of T-Shaped Slot Antenna for UWB Communications Systems

The design and performance of a compact Tshaped slot antenna for ultra wideband (UWB) communication systems is presented in this paper. Multiple resonant bands are generated and unified to form a wider bandwidth from 2.9 to 11.7 GHz for S11