Domenico Gaetano

Footwear Antennas for Body Area Telemetry

Antennas designed to link footwear sensors within body centric networks are introduced with two small UWB antennas, one directional and another quasi-omnidirectional. The radiating characteristics are evaluated for three positions on a sample sports shoe using a detailed simulation model and measurements with a homogenous foot phantom. Antenna performance is assessed for resilience to close proximity loading by the footwear materials and the phantom foot.

Breast cancer detection using interferometric MUSIC: experimental and numerical assessment.

PURPOSE In microwave breast cancer detection, it is often beneficial to arrange sensors in close proximity to the breast. The resultant coupling generally changes the antenna response. As an a priori characterization of the radio frequency system becomes difficult, this can lead to severe degradation of the detection efficacy. The purpose of this paper is to demonstrate the advantages of adopting an interferometric multiple signal classification (I-MUSIC) approach due to its limited dependence from a priori information on the antenna. The performance of I-MUSIC detection was measured in terms of signal-to-clutter ratio (SCR), signal-to-mean ratio (SMR), and spatial displacement (SD) and compared to other common linear noncoherent imaging methods, such as migration and the standard wideband MUSIC (WB-MUSIC) which also works when the antenna is not accounted for. METHODS The data were acquired by scanning a synthetic oil-in-gelatin phantom that mimics the dielectric properties of breast tissues across the spectrum 1-3 GHz using a proprietary breast microwave multi-monostatic radar system. The phantom is a multilayer structure that includes skin, adipose, fibroconnective, fibroglandular, and tumor tissue with an adipose component accounting for 60% of the whole structure. The detected tumor has a diameter of 5 mm and is inserted inside a fibroglandular region with a permittivity contrast εr-tumor/εr-fibroglandular < 1.5 over the operating band. Three datasets were recorded corresponding to three antennas with different coupling mechanisms. This was done to assess the independence of the I-MUSIC method from antenna characterizations. The datasets were processed by using I-MUSIC, noncoherent migration, and wideband MUSIC under equivalent conditions (i.e., operative bandwidth, frequency samples, and scanning positions). SCR, SMR, and SD figures were measured from all reconstructed images. In order to benchmark experimental results, numerical simulations of equivalent scenarios were carried out by using CST Microwave Studio. The three numerical datasets were then processed following the same procedure that was designed for the experimental case. RESULTS Detection results are presented for both experimental and numerical phantoms, and higher performance of the I-MUSIC method in comparison with the WB-MUSIC and noncoherent migration is achieved. This finding is confirmed for the three different antennas in this study. Although a delocalization effect occurs, experimental datasets show that the signal-to-clutter ratio and the signal-to-mean performance with the I-MUSIC are at least 5 and 2.3 times better than the other methods, respectively. The numerical datasets calculated on an equivalent phantom for cross-testing confirm the improved performance of the I-MUSIC in terms of SCR and SMR. In numerical simulations, the delocalization effect is dramatically reduced up to an SD value of 1.61 achieved with the I-MUSIC in combination with the antipodal Vivaldi antenna. This shows that mechanical uncertainties are the main reason for the delocalization effect in the measurements. CONCLUSIONS Experimental results show that the I-MUSIC generates images with signal-to-clutter levels higher than 5.46 dB across all working conditions and it reaches 7.84 dB in combination with the antipodal Vivaldi antenna. Numerical simulations confirm this trend and due to ideal mechanical conditions return a signal-to-clutter level higher than 7.61 dB. The I-MUSIC largely outperforms the methods under comparison and is able to detect a 5-mm tumor with a permittivity contrast of 1.5.

Conformal UWB impulse antenna for pipe telemetry

The fidelity factor of a directional UWB antenna has been investigated for communicating telemetry data from a pipe that can contain liquids. The impedance match and the radiation patterns the antipodal Vivaldi design have been optimized for a 3.1–10.6 GHz bandwidth. The mechanical properties of the substrate material permit limited flexing and in this case, it is curved around the transverse axis of a 56 mm diameter pipe. An initial frequency domain analysis is extended with the study of a 7.5 GHz bandwidth pulse centred at 6.85 GHz. The fidelity factor of the antenna in a free-space environment was measured for comparison with the pipe-mounted setup. The proximity of the antenna and pipe is studied for signal degradation, as is the performance for empty and water-filled conditions.

Impact of Hub Location on the Performance of Wireless Body Area Networks for Fitness Applications

This letter compares the propagation properties of wireless body area networks for three different locations (head, foot, and waist) of the hub/Internet gateway on the human body. The wireless channels between the hubs and four nodes (chest, back, and upper arms) are measured for frequencies between 5 and 7 GHz on a female and a male subject performing push-ups and squats. A framework using path gain and fade depth metrics in spider plots is used for cumulative performance description. The results show that the best overall performance is for a hub located on the temple, and the worst overall performance is achieved for a hub on the waist. These results are expected to stimulate further research into the optimum hub placement on the human body.

Experimental microwave breast cancer detection with oil-on-gelatin phantom

This paper presents a 2-D breast phantom which was realized with oil-in-gelatin materials for the evaluation of three different tumor detection methods operated in the microwave spectrum 1-3 GHz. A planar monopole antenna was used to scan the phantom in a multi-monostatic configuration across 36 angular locations. Results show a better performance of an Interferometric-MUSIC approach when compared to Non-coherent Migration and Wide Band MUSIC.

Antipodal Vivaldi Antenna for Water Pipe Sensor and Telemetry

An antipodal Vivaldi antenna operates simultaneously for telemetry and sensing when placed conformally onto PVC pipes. Good radiation efficiency is realised and the antenna impedance matching remains stable when a pipe is empty or contains water. The fidelity factor performance based on an input Ultra-Wideband Gaussian pulse is a suitable figure of merit to detect water presence. Different water levels and pipe conditions correspond to fidelity factors between 90% and 96%, which are a suitable dynamic range for sensing and the appropriate quality for pulse communications for remote monitoring.

An Antenna for Footwear

Antenna design for footwear is an essential part of enabling reliable wireless links with lower-limb sensors used in body centric networks. Sensors can report biomechanical pressure data to analyse kinematic and posture parameters for a range of medical and sporting applications. Consideration is given to antenna shapes, the fit with shoe shapes, the positioning on the shoe and the radiation patterns suited to on body and off-body communications.

Insole Antenna for On-Body Telemetry

A 433-MHz antenna is proposed for integration with the insole of footwear for a body-area network. The folded dipole design with an asymmetric groundplane radiates from its edges and considers the close proximity of the human foot and ground surfaces. It functions for different ground conductivity conditions and an on-body communication link with an inverted-F antenna in the upper body area was evaluated on a static and dynamic human subject. The antenna solution was compliant with specific absorption rate (SAR) requirements, remains matched and links with upper body nodes regardless of the body posture and node location.

Anatomical loading on a UWB antenna for shoe toe box

A UWB 6.0-8.5 GHz monopole antenna for mounting on the toe-box area of footwear is designed using a detailed model of a running shoe and a foot-shaped phantom. Variation of anatomical features between individual people gives rise to different proximity and permittivity loads on the antenna. To take account of environment, the antenna design optimization considers different proximity distances for impact on the reflection coefficient and on the radiation efficiency.