Manmohan Sharma

A miniature wideband antenna for wearable systems

This paper presents a miniature wideband antenna with a CPW feed fabricated on a Rogers RO 3210 substrate for operation in the top half of the UWB band for utilization in wearable systems, in particular a UWB pulse based time-of-flight motion tracking system. This miniature antenna makes use of a compact SMP connector instead of the traditional SMA coaxial connector. Use of SMP connector further helps in reducing the overall size of the antenna which is 7.9mm × 16.38mm in physical dimensions including the antenna feed. The antenna is small enough that it can fit on a fingertip. Because of its compact size and reasonable performance in the vicinity of human body, the antenna can be used for wearable applications and portable devices. This antenna has been demonstrated to have an impedance bandwidth of 4.9 GHz to beyond 11 GHz. The measured results are in good agreement with the simulations.

Fidelity Pattern Analysis of a CPW-Fed Miniature UWB Antenna Using Different Excitation Pulses

This letter presents numerical and experimental investigations of the fidelity factor of a novel coplanar waveguide (CPW)-fed miniature tapered-slot antenna. Different excitation pulse types have been employed to study the effect of the antenna and the propagation channel on the received pulse quality. The antenna is intended to be used in a pulse-based time-of-flight motion tracking system, which requires minimum distortion to the received pulse for the accurate retrieval of the sent data. A distinguishing aspect about this study is that the fidelity analysis has been carried out both in free-space and with the antenna mounted on the human body considering an extended spatial range compared to previously reported work. The results show that the miniature ultrawideband (UWB) antenna offers a very limited pulse distortion. Excellent average fidelity value of over 0.95 has been obtained by employing appropriate input pulses, even when the antenna is mounted on the human body. Furthermore, the effect of fidelity on communication performance of an ultrawideband antenna system has been studied by modeling an impulse-based UWB system. It has been demonstrated that the high pulse fidelity of the antenna leads to consistent bit error rate (BER) values in various spatial directions.

Experimental investigation of 3D localisation of an on-body UWB antenna using several base stations

This paper presents an experimental study of localisation of a body mounted ultra-wideband (UWB) antenna. Several three-dimensional localisation experiments have been performed, using a miniature tapered-slot antenna mounted on the human body as a mobile station and three Vivaldi antennas as base stations, to comprehend the level of accuracy that can be achieved and assess how precisely the tiny movements of the mobile station could be resolved. Time of Arrival data fusion and peak detection techniques have been used to compute the position of the target node in terms of x, y, z cartesian coordinates. The antennas are envisioned to be employed in a pulse based time-of-flight motion tracking system, using the upper end of the UWB band. The geometry and performance of a UWB Vivaldi antenna designed for the project is also presented.

Time domain analysis of a miniature tapered-slot UWB antenna

This paper presents the time domain study of a miniature tapered-slot ultra-wideband antenna. Firstly, the antenna geometry and frequency domain performance are briefly discussed. Subsequently, a detailed analysis of the time domain behavior of the antenna has been provided. Through the measurements, the transfer function and group delay of the antenna system are obtained. Then, using the convolution approach, the impulse response has been investigated. The antenna is shown to have good performance in time domain as well as frequency domain.

Investigative analysis of the influence of different simplified human body models on a miniature ultra-wideband antenna

This paper presents numerical and experimental study of the influence of various types of simplified human equivalent phantoms and actual human body on the reflection coefficient and bandwidth of a miniature ultra-wideband antenna. Four multi-layered body models, with different geometries and cross-sections, along with both dispersive and non-dispersive characteristics have been used in the analysis. A sensitivity analysis of the UWB antenna to the distance from the body models and their sizes has been provided to assess the most suitable model in terms of accuracy and computational time. Measurements have also been carried out with the antenna placed in close proximity to a real human test subject and results have been compared.

Wireless telemetry performance of transplanted organ monitoring at ultra wideband range considering respiration-induced organ movement

In this paper, we aim to assess the performance of a transplanted organ monitoring system by considering the effect of respiration-induced organ movements and locations of the on-body antenna. A heterogeneous human model was used in our numerical investigations. The performance of an implanted antenna and its in-body channels around the liver area are studied using ultra wideband (UWB) technology. S-parameter results for various separating distances between the implanted antenna and the on-body antenna were acquired and investigated. The results demonstrate the influence of organ movement as well as the surrounding tissues on the level of signal attenuation. Our analysis indicates that UWB channel has the potential to be successfully utilized for the transplanted organ monitoring in this in-body scenario.

UWB Sensor Nodes for Tracking of Human Motion in Medical and Rehabilitation Applications

This paper presents the experimental and investigational studies involving the use of compact ultra-wideband sensor nodes for tracking the human body motion. A standalone ultra-wideband positioning system developed by making use of commercially available impulse-radio UWB chips has been utilized for the localisation measurements. The operating principles of the technique used for position estimation and the results of various three dimensional localisation measurements undertaken using the system are provided. Details of the transmitter and receiver antennas and the UWB chip, the core components of this system have been discussed. Average localisation accuracy in the range of 1 to 5 cm has been achieved. The system makes use of time difference of arrival approach to estimate the 3D position of the target on-body node.

Investigation of TOA-Based Ranging Accuracy of a Miniature Ultra-Wideband Antenna for Human Motion Capture Applications

This paper presents an investigative study of the ranging capabilities of a miniature tapered-slot UWB antenna and an analysis of the influence of the human body on the accuracy of range estimates. The study involves determining how precisely the point-to-point distance between two identical tapered-slot antennas can be deduced through the signal Time-of-Flight from the transmitting antenna to the receiving antenna. Channel Impulse Response and peak detection techniques have been used for range estimation. Both on-body and free-space scenarios have been considered for this study. Very high accuracy is observed in calculating the range estimates between the two antennas, both when the antennas are in free-space and when placed on the human body.