Nisha Sarwade

Antenna Array Performance with Number of Elements for Aperture Distributions

ABSTRACT The main feature of an antenna array is its ability to form and scan the shaped main beam by using the amplitude and phase inputs as the controlling parameters at element level. In this paper, a comprehensive analysis of various parameters of a uniformly spaced linear array with respect to a number of elements for different amplitude distribution/window functions has been presented. There is a general assumption that any given window function will realize the expected parameters of the array even for a small number of array elements. A systematic study has been done to bring out very clearly the minimum number of elements that is required to realize antenna performance for a particular amplitude distribution. Effect of number of elements to obtain the desired first side lobe level and efficiency is presented. Contributions have been made to discuss the effects on directivity, gain, and beamwidth of the linear array.

Simulation of lock in amplifier (LIA) for very low signal measurements

In this paper we present the simulation of a Lock-in amplifier completely based on LabVIEW. The software processes the signal analysis of the submerged intelligent signal in noise. We describe some characteristics of the Lock in amplifier including output voltage vs. phase and output phase vs. noise. Lock in Amplifier is used to measure the very small signals, even in the presence of broadband noise, which is several times greater than the signal itself. Since the signal processing takes place on the computer, the output is display in the form of waveform. Tab Based system will allow easy access of LAB VIEW Software.

Design analysis and testing of Wilkinson Power Divider with harmonics suppression using Defected Ground Structures

Wilkinson Power Divider is a passive component used in wireless communication as a key device, for dividing RF / microwave power. Defected Ground Structures (DGS) have been developed to improve characteristics of microwave devices & circuits, due to its band-stop property. In this paper, a new effective technique of suppression of second & third harmonic in Wilkinson Power Divider is proposed by using two square headed dumb-bell shaped DGS. The electromagnetic simulation results obtained by using IE3D software shows fairly good agreement with the results gained by applying basic transmission line theory & with the testing results found after implementation of the proposed device. As per the testing results, the error in shift in the frequency where it has maximum return loss is 6.8%. This is due to fabrication tolerances & high-frequency parasitic effect.

Non-Identical Rectangular Microstrip Antenna Arrays for Amplitude Tapering

ABSTRACT A design technique of an antenna array with amplitude distribution/tapering to suppress the first side lobe level by exploiting the property of the rectangular microstrip antenna (RMSA) is proposed. Non-identical antenna array elements have been designed using the RMSAs by varying their width and hence the gain (keeping the length and hence the frequency same) to obtain the amplitude distribution for a desired first side lobe level. This eliminates the need of a complicated feed network with unequal power division to realize amplitude tapering. The conceptualized design is verified for a number of corporate-fed arrays and an analysis is carried out to give design guidelines with respect to the number of elements in the array. A symmetric corporate-fed 8-element antenna array with a cosine-square over pedestal amplitude distribution, operating at 1.8 GHz, has been designed and fabricated to validate the proposed concept. There is a reasonable agreement between simulated and measured results.

Connectivity Model for Molecular Communication-Based Nanomachines Network in Normal and Sub-diffusive Regimes

Nanomachines network is an interconnection of nanomachines (NMs) capable of communicating with each other. NMs networks are expected to provide an intelligent alternative to contemporary wireless sensor networks due to their biocompatibility, pervasiveness, and energy efficiency. However, connectivity issues of NMs networks are yet to be explored fully. This paper presents a probabilistic connectivity model for molecular communication-based NMs network which involves transmission of a message via diffusion of messenger molecules. This model has been developed through signal to interference and noise ratio (SINR) analysis considering effects of co-channel interference (CCI) and intersymbol interference (ISI). It is found that ISI is the dominating factor in degrading the network connectivity than CCI. Also, results have shown that selection of symbol time is crucial and should depend on internode distance (or transmission range), for higher network connectivity. Physical obstructions in transmission media lead to anomalous diffusive behavior. This paper has investigated effects of sub-diffusion on the connectivity of NMs network to reveal that presence of physical obstructions can be a favorable condition in MC-based NMs networks if symbol time is adjusted accordingly.

On the performance of quantum cryptographic protocols SARG04 and KMB09

Since the first protocol, proposed by Benette and Brassard in 1984 (BB84), the Quantum Cryptographic(QC) protocols has been studied widely in recent years. It is observed that most of the later QC protocols are variants of BB84 with the intention of addressing one or more problems incurred during the practical implementation of BB84 protocol. Amongst many candidates, SARG04 provides robust performance for the weak coherent pulse implementation of QC. Another follower protocol, KMB09 provides improvement in quantum communication distance between Alice and Bob (the classical communicating parties). Both these protocols are chosen to compete, as they found to be a suitable choice for incorporating QC in existing wireless technology. In this paper we present the performance analysis of these two protocols with respect to protocol efficiency, Quantum Bit Error Rate (QBER) and robustness against eavesdropping.

Signal processing of Spectral Domain Optical Coherence Tomography

Medical imaging techniques that are found in hospitals are X-ray imaging, MRI, ultrasound imaging, CT scan. Recently, a lot of scientific research work is being carried out with the aim of the improvement of these methods and the discovery of new non-invasive techniques. As a result, a new optical imaging technique, called Spectral Domain Optical Coherence Tomography (SD-OCT) was proposed in the early 2000s. Optical Coherence Tomography (OCT) is an emerging imaging technique having resolution in the μm range and depth of imaging in the mm range. In this paper we have described the basic principle, theory, types of OCT, signal processing steps and its applications in medical field. We have discussed some of the results related to signal processing that we got from simulation using MATLAB and Lab VIEW.

Designing and performance analysis of nano machines network for synthetic immune system

Nano machines network is a new networking concept wherein molecular cell sized devices perform specific tasks while coordinating with each other using molecular communication. Such a network can be employed to develop synthetic immune system. In this paper, a nano machines network is designed to mimic negative selection mechanism used in biological immune system. Since negative selection is used to perform binary classification, such a network can be used in real life applications like air/ water purification, detecting oil spill in water bodies, surveillance against chemical and biological weapons etc. For performance analysis of this design, the network is treated as a single server queue. For simulation, the inter-arrival time is generated on the basis of viral infection model while service time is based on inverse Gaussian distribution.

Naturally Tapered Series Fed Arrays for First Sidelobe Level Reduction

Series fed arrays with feed at the centre element have been used as a natural tapered array for first sidelobe level (FSLL) reduction. The fact that all elements of the series fed arrays do not receive equal power has been used to realize natural tapering in these arrays. An analysis with respect to number of elements and size of the elements for the series fed arrays used is clearly brought about.

A compact modified corporate feed network for antenna arrays with non-identical rectangular microstrip antenna elements

An antenna array with modified compact feed has been designed with non-identical elements using cosine square amplitude distribution with the purpose of reducing the first side lobe level. The proposed feed network uses an overall area of 25.47% less than that of a similar array with conventional corporate feed network. Experimental results of this six element array validate the theoretical parameters.