Anastasios Paraskevopoulos

On-body measurements of embroidered spiral antenna

This paper presents a compact and flexible embroidered spiral antenna that can be used for wearable applications. The antenna is embroidered by using a state of the art digital embroidery machine with multi-strand conducting thread Liberator™. The antenna has been measured on a Specific Anthropomorphic Mannequin (SAM) phantom and a real human. The measurement results show that the SAM phantom emulates the dielectric properties of the human body in a wide frequency band from 0.3 to 3 GHz. The far-field on-body performance of the antenna has been measured by placing the antenna on the SAM phantom in a tapered Anechoic Chamber. Near-field to far-field transformations have been used to produce the far-field performance including radiation pattern, directivity, rrealised gain and radiation efficiency.

Modelling of dynamic on-body waist-foot channel at 2.45 GHz

In this paper the dynamic communication channel is investigated between wearable antennas mounted on human body. The work has been focused on modelling the on-body waist-to-foot communication channel commonly used in sports and entertainment applications. The influence of body movement during walking and running actions on the channel path loss is investigated. The effect of the antenna type is also accounted by using two different printed antennas, Inverted-F antenna (IFA) and higher mode microstrip patch antenna (HMMPA), operating at 2.45 GHz ISM band. Slow fading effect due to body motion and polarization mismatch of antennas has been studied. For this purpose, extensive EM simulations using an adequate number of different body postures derived from animation software have been done.

Investigation of wearable antennas performance in static LOS and NLOS on-body channels

In this paper modelling of specific on-body channels is conducted by using three different antenna types. Our goal is to investigate antennas performance in different on-body contexts and examine antennas propagation mechanisms. For this purpose, a measurement campaign is performed. Results will be provided in terms of channel gain, slow and fast fading modelling by performing statistical analysis of received signal envelope.

A printed monopole ESPAR antenna for Truck-to-Truck communications

Driver safety, traffic efficiency and green transportation can be significantly improved by Truck-to-Truck (T2T) communications. This paper proposes a 5.9 GHz Electronically Switched Parasitic Array Radiator (ESPAR) antenna that employs three printed monopoles as array elements. The antenna demonstrates a reconfigurable radiation pattern and compact dimensions that make it ideal for installing it in the side mirrors of a heavy duty vehicle (truck). By adjusting the voltage supply at two PIN diode switches, the antenna can operate in three different states and provide three different radiation patterns (one quasi-omni, two directive beams) to the T2T link user. An ESPAR antenna prototype is manufactured and experimentally characterized, demonstrating a good agreement between simulation and experimental results. The proposed antenna exhibits a satisfying impedance matching and a considerable gain enhancement in the two opposite directions when the antenna operates in the directive mode. An interesting investigation is also performed on the exact location of the antenna inside the truck side mirror.