Interaction of antenna systems with human body

The research investigates the influence on the human body on a communication system. To understand this, the effect of hands free kit (HFK) on energy absorption in the body was investigated when operating a smart phone at 2G. Findings on the research are given in the thesis report. Also, the influence of the way in which a phone is held on a phone s received power was investigated. The result was compared to that obtained using a hand phantom acquired from SPEAG. This was to check if the hand phantom best represents the human hand when using it in experiments. The setup for the experiment was in an anechoic chamber at Loughborough University. The mobile phone transmitted in the 2G system. In further experiments carried out on the body, two antennas were attached to the body in six different orientations to receive power from a source creating a Single Input Multiple Output (SIMO) system. The antennas used were monopoles mounted on a circular ground plane. These antennas were designed and constructed with the influence of the body taken into consideration. The use of diversity techniques to improve transmission to an on-body system is investigated with the antennas on the body. For each alignment, the transmission to the on-body was compared with the transmission to the corresponding off-body (free space). Experiments for this work were carried out in three environments

SAR variations in the face due to semi-rimmed spectacles and polarized sources at GSM900 and GSM1800

This paper presents experimental and simulated results from a study looking at the effects of semi-rimmed spectacles on the specific absorption rates (SAR) inside the head. Measurements were carried out using a modified specific anthropomorphic mannequin (SAM) phantom head incorporated into a DASY4. 1g SAR was recorded for 14 different semi-rimmed spectacles using CW dipole sources at 900MHz and 1800MHz. Simulations have also been conducted using the digitised SAM head and a pair of spectacles

Rohacell radomes for delicate antennas on the body at 2.4GHz

This paper presents the use of two generic on-body antenna types, a probe and a magnetic dipole with and without a radome constructed of Rohacell. Its is shown that Rohacell minimally attenuates the electromagnetic signal transmitted or received by the antenna concluding to the cover being essentially transparent to radio waves at 2.4GHz and 5.8GHz. In on-body meaurements radomes can be used to protect the antenna surfaces from damage and protect nearby personnel from being accidentally struck by quickly rotating antennas. Performance of two on-body antennas is considered on and off the body by measurement and simulation. Results show that the Rohacell protection has negligible effect on the performance of the antenna systems regardless of loading by humans and polarity. This paper aims to enlighten use of Rohacell to protect antennas used for body centric experiments and experiments in body-centric settings

Human effect on twin antenna on-body for three diversity techniques at 2.4 GHz

Since the user is generally in the near field On-body antennas are accepted as more complex to optimise than their free space counterparts. Use of the body as a platform for wearable electronics is a topical subject. Omnidirectional antennas are thought to be useful for antennas in body area networks. However, the desirable properties of omnidirectional radiation patterns close to humans are severely diminished due to the lossy load nature of biological matter and high levels of scattering due to shadowing and mismatch. To alleviate these problems two or more antennas can be used on the body. In this paper, two on body antennas are used with three different combination techniques in order to evaluate the diversity performance and then compared with their free space equivalents. Three diversity techniques are used – Selective, Maximal Ratio and Equal Gain. The frequency of operation was 2.4GHz

A study of perturbations in linear and circular polarized antennas in close proximity to the human body and dielectric liquid filled rectangular and a cylindrical phantom at 1.8 GHz

In the design and synthesis of wearable antennas isolation distance from the body is a critical parameter. This paper deals with the comparison of perturbations caused to the matching of simple linear and circular polarized patch antennas due to the close proximity of a human torso and rectangular box and cylindrical phantoms filled with muscle simulating liquid at 1.8GHz. The isolated variable is return loss, S11(dB). Results show that at these frequencies a cylindrical phantom resembles the body more closely than a rectangular phantom

A study of perturbations in linear and circular polarized antennas in close proximity to the human body and dielectric liquid filled rectangular and a cylindrical phantom at 1.8 GHz

In the design and synthesis of wearable antennas isolation distance from the body is a critical parameter. This paper deals with the comparison of perturbations caused to the matching of simple linear and circular polarized patch antennas due to the close proximity of a human torso and rectangular box and cylindrical phantoms filled with muscle simulating liquid at 1.8GHz. The isolated variable is return loss, S11(dB). Results show that at these frequencies a cylindrical phantom resembles the body more closely than a rectangular phantom

Human effect on on-body selective combining at 2.4 GHz

Use of the body as a platform for wearable electronics is a topical subject. Omnidirectional antennas are thought to be useful for antennas in body area networks. However, the desirable properties of omnidirectional radiation patterns close to humans are severely diminished due to the lossy load nature of biological matter and high levels of scattering due to mismatch. To alleviate these problems two or more antennas can be used on the body. In this paper, two on body antennas are used with selective combining and then compared with their free space equivalents. The frequency of operation is 2.4GHz