Saswati Ghosh

Ultrawideband Performance of Dielectric Loaded T-Shaped Monopole Transmit and Receive Antenna/EMI Sensor

This letter presents the performance of a T-shaped monopole antenna loaded with an annular dielectric resonator as an ultrawideband transmitting/receiving antenna. By adjusting the length of the monopole and load arm, a 10-dB bandwidth of 110% is achieved while maintaining monopole-like radiation pattern. The antenna factor of the same antenna, while used as electromagnetic interference (EMI) sensor is also presented for the desired and cross-polarized component of incident electric field. The results for antenna factor show an ultrawide bandwidth with the cross-polarization isolation better than 86 dB/m for the T-monopole/DRA as EMI sensor. The simulated result for return loss is verified with the measured data from a prototype antenna.

LOADED WIRE ANTENNA AS EMI SENSOR

This paper describes the performance of different loaded wire antennas (e.g., inverted L, T, I and C-shaped antennas) as electromagnetic interference (EMI) sensors. Loaded wire antennas in transmitting mode are widely used for low frequency communication. However, while using these antennas as EMI sensors, the extra loading is likely to introduce the reception of cross-polarized component of incident electric field and investigation on this has not yet been performed. This paper highlights the results of the initial investigation on the performance of these loaded antennas as EMI sensors in terms of the Antenna Factor for the desired and cross-polarized component of incident electric field. The Method of Moments with Pulse basis function and Point-matching technique has been used to evaluate the current distribution on the antenna surface and hence the Antenna Factor.

Band-Notched Modified Circular Ring Monopole Antenna for Ultrawideband Applications

This letter proposes a planar modified circular ring antenna for ultrawideband (UWB) applications with band notch performance. By suitably adjusting the antenna parameters, a return loss of 10 dB is achieved over the desired frequency range (3.110.6 GHz) except the notch frequency band. The band-notched characteristic is achieved by introducing a tuning stub inside the ring monopole. The results for return loss and radiation pattern are simulated using electromagnetic simulator WIPL-D. The time domain behavior of the antenna in terms of the fidelity factor is evaluated using Computer Simulation Software (CST) transient solver. A prototype antenna is fabricated, and the simulated result for return loss is compared to the measured result.

Design of Planar Crossed Monopole Antenna for Ultrawideband Communication

This letter proposes a planar crossed monopole antenna for ultrawideband application. The numerical simulations using Computer Simulation Technology (CST) transient solver and WIPL-D demonstrate that the impedance bandwidth of a rectangular monopole dramatically increases by including the cross plate. Parametric study on the crossed plate parameters is conducted to achieve the return loss of 10 dB over the desired frequency range (3.1-10.6 GHz). The stability of radiation pattern is also presented. The measured result for the return loss of a prototype antenna shows the same bandwidth as the simulated result.

Simple Crosstalk Model of Three Wires to Predict Nearend and Farend Crosstalk in an EMI/EMC Environment to Facilitate EMI/EMC Modeling

Electromagnetic coupling to cables has been a major source of EMC and EMI problems. In this paper, the methods of predicting the EM coupling and propagation in multiconductor transmission lines are presented. Crosstalk is an important aspect of the design of an electromagnetically compatible product. This essentially refers to the unintended electromagnetic coupling between wires and PCB lands that are in close proximity. Crosstalk is distinguished from antenna coupling in that it is a near field coupling problem. Crosstalk between wires in cables or between lands on PCBs concerns the intra-system interference performance of the product, that is, the source of the electromagnetic emission and the receptor of this emission are within the same system. With clock speeds and data transfer rates in digital computers steadily increasing, crosstalk between lands on PCBs is becoming a significant mechanism for interference in modern digital systems. To predict the crosstalk we designed a simple model of three conducting wires and took measurements for both nearend and farend crosstalk. Also the same model is being simulated by CST Microwave Studio (3D Electromagnetic Solver).

A Network Coding based Probabilistic Routing scheme for Wireless Sensor Network

Network coding scheme improves throughput and reliability in a Wireless Sensor Network. A straight forward broadcasting by flooding in a wireless sensor network is very costly and reduce the network coding benefit. The packet loss probability increases due to contention and collision which is referred as broadcast storm problem. In this paper, we have proposed a Network Coding based Probabilistic Routing scheme (NCPR) for wireless sensor network that alleviate the broadcast storm problem. The NCPR scheme also improves the network coding gain which is defined as the ratio of the native data packets transmitted with network coding to the number of data packets transmitted without network coding using same number of transmissions. Furthermore, for a large scale network the clusters are restricted to some geographical area and they want to share information with each other (battlefield scenario). In NCPR, the decoding operation can be carried at the intermediate nodes rather than only at the sink node; both intra-cluster and inter-cluster information sharing is considered. The protocol also gives protection to the sensor nodes against link failure. Simulation results are presented, which show high degree of coding gain than the flooding scheme.

Network coding-aware data aggregation for a distributed Wireless Sensor Network

Wireless Sensor Networks (WSNs) are immensely deployed for monitoring information like humidity, temperature and soil fertility. As the sensor nodes sense data and floods them in the network, the network traffic increases and may result in congestion which leads to broadcast storm problem. This paper addresses the utility of network coding to optimize data aggregation and to decrease the number of transmitted messages in a WSN. A coding-aware deployment strategy is presented which create opportunity for network coding at aggregate sensor nodes. Our deployment strategy leads to a topology which supports many-to-many network flows (multiple sources and multiple sink network flow). It also gives protection against multiple failures in the network. Furthermore, we propose a heuristic that restricts unnecessary transmissions.

ESTIMATION OF ANTENNA FACTOR OF MICROSTRIP PATCH ANTENNA AS EMI SENSOR

This paper presents the result for antenna factor of microstrip patch antenna when used as electromagnetic interference (EMI) sensor. Antenna factor is an important parameter of a sensor used for EMI measurements. The microstrip antenna has found wide application as transmit and receive antenna in modern microwave systems. In this paper, a new application of microstrip antenna as EMI sensor is presented. The result for antenna factor versus frequency of a microstrip patch antenna is presented using commercial software CST Microwave Studio. Also the experimental results for a prototype antenna are presented and compared with the simulated result.

Estimation of equivalent circuit of loaded trans-receive antenna system and its time domain studies

The time domain studies of different reduced-height loaded wire antennas (e.g., inverted L, T, I and C-shaped antennas) when used in trans-receive system is presented. Due to the reduced height of the loaded antennas, these antennas have found wide application as transmitting and receiving antenna/sensors for electromagnetic interference (EMI) measurements. However, while using these antennas in trans-receive system for wideband application, the time domain characterization of both the transmit and receive antenna is required and investigation on this has not yet been performed. This paper presents the results of the initial investigation on the time-domain performance of these loaded trans-receive systems. An optimized transmit antenna generator waveform is used to maximize receive antenna voltage amplitude (with bounded input energy), as presented in the recent literature. The frequency domain Method of Moments with Pulse basis function and Point-matching technique has been used to evaluate the current distribution on the antenna surface and hence the radiated electric field at the position of the receiving antenna. The same technique has been extended for receiving wire antenna to evaluate the Complex Antenna Factor (CAF) of these antennas. The CAF versus frequency data has been used to evaluate the input and output voltage waveform of the trans-receive system. The results have been verified with theoretical and experimental data available in reported works.

Estimation of Antenna Factor of Wire Antenna as Emi Sensor

The ratio of incident electric field at the surface of receiving antenna to the received voltage at the antenna terminal when terminated in 50 ohms load is known as the antenna factor. It is an important parameter of a sensor used for EMI measurements. To determine electromagnetic radiation from an electronic component it is required to evaluate the field strength at a certain distance from it using the sensor. If the antenna factor of the receiver and the received voltage are known then the field can be found out applying simple relations. In this paper a simple and useful Method of Moment-based theoretical technique is described to evaluate the antenna factor of wire antenna. The wire is considered as perfectly conducting with radius much less compared to the wavelength of operation. The wire is divided in large number of small segments. A point matching technique is applied to evaluate the surface current distribution due to the incident electric field. The output impedance is found out from the short circuit current and the open circuit voltage of the wire. The received voltage and hence the antenna factor is evaluated from the equivalent circuit diagram of the antenna. The data for current distribution on the antenna in receiving and transmitting mode and input impedance for transmitting mode are well comparable to the results available in literature. Studies have been extended for off-centered antenna and for oblique incidence of electric field.