Jayanti Venkataraman

Analysis of Arbitrarily Oriented Microstrip Transmission Lines in Arbitrarily Shaped Dielectric Media Over a Finite Ground Plane

A numerical analysis is presented for a multiconductor transmission line in multilayered Iossy, dielectric regions where the ground plane is of finite extent. The transmission fines are infinitely long and vary in cross section from finite to infinitesimally thin. The Greens function for such a two-dimensional transmission line involves an arbitrary constant. If the ground plane is infinite, the method of images could be used where this constant cancels out. However, in the case of a finite ground plane, the constant has to be evaluated. Here a numerical method is presented where the constant could be eliminated rather than evaluated by imposing the condition for the total charge to be zero. The transmission lines, dielectric regions, and the ground plane can have arbitrary cross sections.

Printing Radio Frequency Identification (RFID) Tag Antennas Using Inks Containing Silver Dispersions

Abstract Rotary letterpress and flexographic printing were investigated for their potential use in making electrically conductive structures. A variety of test patterns were designed to determine some of the printing process capabilities. Antennas for radio frequency identification tags were printed using these techniques. The ink used in this study was a dispersion of silver flakes, and organosilver compounds in an organic vehicle. A variety of printing parameters (inking time, inking speed, printing speed, and printing force) were studied. The printed test patterns and antennas were characterized by a profilometry, electron and optical microscopy, and electrical measurements.

Feasibility study for non-invasive blood glucose monitoring

The present work investigates the feasibility of a non invasive blood glucose monitoring system using an antenna placed in a cuff and wrapped around the wrist. The technique is based on the fact that glucose levels affect the dielectric properties of blood. Using a realistic tissue model of a human hand, simulations have been performed with HFSS to obtain the antenna input impedance. The resonant frequency is seen to shift with changes in blood glucose levels. Based on our previous work of tissue characterization, an analytical technique can be developed to relate this frequency shift to the permittivity and conductivity of blood, from which the glucose levels are determined.

A Feasibility Study of Tissue Characterization Using LC Sensors

Bio-implantable sensors using radio-frequency telemetry links that enable the continuous monitoring and recording of physiological data are receiving a great deal of attention. The objective of this paper is to study the feasibility of an implantable sensor for tissue characterization. This has been done by querying an LC sensor surrounded by dispersive tissues by an external antenna. The resonant frequency of the sensor is monitored by measuring the input impedance of the antenna, and correlated to the desired quantities. Using an equivalent circuit model of the sensor that accounts for the properties of the encapsulating tissue, analytical expressions have been developed for the extraction of the tissue permittivity and conductivity. Finally, experimental validation has been performed with a telemetry link that consists of a loop antenna and a fabricated LC sensor immersed in single and multiple dispersive phantom materials.

Feasibility of non-invasive blood glucose monitoring: In-vitro measurements and phantom models

The objective of the present work is to demonstrate the feasibility of non-invasively monitoring blood glucose levels. The technique is based on relating a monitoring antennas resonant frequency to the permittivity and conductivity of blood which in turn is related to the glucose levels. At first a realistic data base for the dielectric properties of blood was established through in-vitro measurements performed on blood samples obtained from 10 patients with glucose levels ranging from normal (87 mg/dl) to hyperglycemic (330 mg/dl). Using the Agilent 85070E dielectric probe and an Agilent 8720B network analyzer the dielectric permittivity and conductivity of the blood samples were measured over a frequency range of 1GHz – 10GHz. The resonant frequency of a wideband antenna strapped to the patient was monitored as the patient ingested fast acting glucose tablets. It has been noted that the antenna resonant frequency increases as the glucose level increases. Blood phantom models have been built to replicate in-vitro measurements and the shift in the resonant frequency has been demonstrated. The work in progress is the development of an analytical model to relate the antenna response to the glucose level.

Size reduction in microstrip antennas using left-handed materials realized by complementary split-ring resonators in ground plane

The present work focuses on using left-handed materials (LHMs) for size reduction of microstrip antennas. Section I discusses the choice and design of a suitable periodic structure to realize negative permittivity and/or permeability. The Complementary Split-Ring Resonator (CSRR) is easiest to implement. Section II discusses the design and construction of the antennas with CSRRs in the ground plane. Design, construction and measurement have been performed and validated with simulated results. In Section III, based on the simulated and measured results a design methodology is proposed.

A Wireless Interconnection Framework for Seamless Inter and Intra-Chip Communication in Multichip Systems

Computing modules in typical datacenter nodes or server racks consist of several multicore chips either on a board or in a System-in-Package (SiP) environment. State-of-the-art inter-chip communication over wireline channels require data signals to travel from internal nets to the peripheral I/O ports and then get routed over the inter-chip channels to the I/O port of the destination chip. Following this, the data is finally routed from the I/O to internal nets of the destination chip over a wireline interconnect fabric. This multihop communication increases energy consumption while decreasing data bandwidth in a multichip system. Also, traditional I/O does not scale well with technology generations due to limitations of pitch. Moreover, intra-chip and inter-chip communication protocol within such a multichip system is often decoupled to facilitate design flexibility. However, a seamless interconnection between on-chip and off-chip data transfer can improve the communication efficiency significantly. Here, we propose the design of a seamless hybrid wired and wireless interconnection network for multichip systems with dimensions spanning up to tens of centimeters with on-chip wireless transceivers. We demonstrate with cycle accurate simulations that such a design increases the bandwidth and reduces the energy consumption in comparison to state-of-the-art wireline I/O based multichip communication.

Gain enhancement of patch antenna using double negative superstrate realized by a high dielectric with triangular lattice of holes

There are many methods for size reduction of microstrip antennas most of which come at the expense of the gain. Amongst techniques for gain enhancement, one method uses double negative material (DNG) as superstrates. In this paper, the DNG material developed in [1] has been used as a superstrate. From an analysis of different configurations of the antenna and the DNG superstrate, gain enhancement of 3.5 dB and radiation patter beam shaping have been achieved.

IMPUT IMPEDANCE TO A PROBE-FED RECTANGULAR MICROSTRIP PATCH ANTENNA

ABSTRACT An improved theory for the input impedance of a probe-fed microstrip patch antenna has been developed. The natural modes are established on a transverse resonance condition which incorporates the angularly dependent reflection coefficients and a dynamic wall susceptance associated with the patch boundaries. The input reactance is shown to be largely associated with the evanescent waves confined to the vicinity of the probe while the input resistance is associated with the excitation of the mode at resonance. Analytical results are presented to describe the input impedance of a rectangular patch antenna as a function of its dimensions, substrate thickness and dielectric constant, probe dimensions and location and the frequency.

On the Benefits of Creeping Wave Antennas in Reducing Interference Between Neighboring Wireless Body Area Networks.

We consider the on-body, off-body, and body-to-body channels in wireless body area networks utilizing creeping wave antennas. Experimental setups are used to gather measurements in the 2.4 GHz band with body area networks operating in an office environment. Data packets providing received signal strength indicators are used to assess the performance of the creeping wave antenna in reducing interference at a neighboring on-body access point while supporting reliable on-body communications. Results demonstrate that creeping wave antennas provide reliable on-body communications while significantly reducing inter-network interference; the inter-network interference is shown to be 10 dB weaker than the on-body signal. In addition, the inter-network interference when both networks utilize creeping wave antennas is shown to be 3 dB weaker than the interference when monopole antennas are used.