Informatics Publishing Limited

U. Ratna Kumari ¹, P. Mallikarjuna Rao ², G. S. N. Raju ³

Affiliations
1 Department of ECE, GIT, GITAM University, Visakhapatnam – 45, IN
2 Department of ECE, AU College of Engineering, Andhra University, Visakhapatnam-03, IN
3 Department of ECE, AU College of Engineering, Andhra University, Visakhapatnam-03, IN

Abstract

The Circular Antenna Array with Dipole radiators is practical antenna array to scan the entire azimuthal plane. The beams with narrow beamwidth and less side lobe level are very useful point to point communication. As the Circular Antenna Array suffers with high sidelobe level and broad beam problems an attempt is made here to reduce these radiation parameters with an efficient metaheuristic optimization technique BAT algorithm. Thinning process is applied on the optimized array for better results. An extensive comparison is brought out between optimized thinned array and uniformly distributed fully populated array.

Keywords

Circular Antenna Array, Dipole, Narrow Beams, Bat Algorithm and Thinning.

Full Text

     

S. Aruna ¹, G. S. N. Raju ¹, P. V. Sridevi ¹

Affiliations
1 Department of Electronics and Communication Engineering, College of Engineering (A), Andhra University, Visakhapatnam - 530003, Andhra Pradesh, IN

Abstract

In defence radar applications, slotted waveguides have excellent, predictable and replicable antenna parameters, when their mechanical manufacturing tolerances defined accurately and controlled. Open slot radiators in the narrow wall of rectangular waveguides are popularly used in several radar applications. Slots used are either longitudinal or inclined depending on the desired polarizations. The longitudinal slots are used for the generation of vertical polarized fields and vertical slots are used for horizontally polarized fields. Sometimes both polarizations are required in succession in defence radar applications. However when longitudinal inclined slots are coupled to a T-arm forming H-plane T-junction, they produce only vertically polarized fields. In this case it is possible to have more parameters for the design of the arrays. At the same time above two types of radiators exhibit different characteristics. In the view of this fact, intensive investigations are made, to bring out and consolidate their comparative characteristics. The admittance parameters, coupling and VSWR are numerically computed using the concept of TE, TM, hybrid and self-reaction concepts.

Keywords

H-Plane T-Junction, Hybrid and Self-Reaction, Longitudinal or Inclined Slot, Open Slot Radiators, Rectangular Waveguides, VSWR.

Full Text

   

U. Ratna Kumari ¹, P. Mallikarjuna Rao ², G. S. N. Raju ²

Affiliations
1 Department of ECE, GITAM University, Visakhapatnam – 45, IN
2 Department of ECE, AU College of Engineering, Andhra University, Visakhapatnam - 03, IN

Abstract

Pattern Synthesis is one of the important problems in all communication systems including radars. The beams with narrow beamwidth and less side lobe level are very useful in point to point communication. Most often patterns are designed using conventional design techniques. However, most of them do not yield optimized and desired patterns. In view of all these facts, intensive investigations are carried out thoroughly on the pattern synthesis techniques with the objective of obtaining narrow beams with low sidelobes from linear arrays using different novel evolutionary algorithms. The Linear Antenna Array with Dipole radiators is practical antenna array to scan the entire azimuthal plane. Hence different Optimization techniques are applied on this Linear Antenna Array. Later thinning process is applied on the optimized array for better results. An attempt is made to compare Optimized thinned array and uniformly distributed fully populated array. The results are found to be very much effective which can be used for different wireless communication applications.

Keywords

Sidelobe Level, Narrow Beams, Optimization, BAT Algorithm, Thinning.

Full Text

     

K. Sravan Kumar ¹, Babak Yazdanpanah ¹, G. S. N. Raju ²

Affiliations
1 Center for Biomedical Engineering, Department of ECE, Andhra University, Visakhapatnam, IN
2 Department of Electronics and communication Engineering, Andhra University, Visakhapatnam, IN

Abstract

Electrocardiogram (ECG) signal is generally corrupted by various artifacts like baseline wander, power line interference (50/60 Hz) and electromyography noise and these must be removed before diagnosis. The task propounded in this article is removal of low frequency interference i.e. baseline wandering and high frequency noise i.e. electromyography in ECG signal and digital filters are implemented to delete it. The digital filters accomplished are FIR with various windowing methods as of Rectangular, Hann, Blackman, Hamming, and Kaiser. The results received are at order of 300,450,600.The signal taken of the MIT-BIH database which contains the normal and abnormal waveforms. The work has been in MATLAB where filters are implemented in FDA Tool. The result received for entire FIR filters with various windows are evaluated the waveforms, power spectrums density, signal to noise ratio (SNR) and means square error (MSE) of the noisy and filtered ECG signals. The filter which shows the excellent outcomes is the Kaiser Window.

Keywords

ECG, FIR Filter, Windowing Methods, MATLAB.

Full Text