The design of multi-band planar inverted-F antennas for mobile handsets with the aid of a novel genetic algorithm and their specific absorption rate

Wireless communications have progressed very rapidly in recent years and mobile handsets are becoming smaller and smaller. Present-day mobile cellular communication systems include combinations of the AMPS, GSM-900, DCS-l800, PCS-1900, UMTS, and WLANs in the 2.4GHz and 5.2GHz bands. User requirements for access to the various aforementioned wireless telecommunication services have resulted in a rapid technological push to unify these different systems in a drastically decreased size single mobile handset. All this combined with strict limitations set for the energy absorbed by the users of mobile terminals has created a need for improved antenna solutions and better understanding of small antennas. The objective of this thesis is to develop novel multi-band handset antenna design solutions to satisfy the specific bandwidth requirements of mobile cellular communication systems. [Continues.

A Study on EMF Exposure Assessments With Different Metrics for User Equipment Antennas at 6 and 10 GHz

User equipment (UE) needs to comply with regulations limiting the exposure of the human body to electromagnetic fields (EMFs). In this paper, three exposure metrics including specific absorption rate (SAR), incident power density, and absorbed power density are quantified for different UE antenna designs. The study is conducted for three antennas - planar dipole, inverted-F antenna (IFA), and planar inverted-F antenna (PIFA), at two frequencies - 6 and 10 GHz, and for evaluation distances from 4 to 10 mm, which are within or close to the antenna’s reactive near field. The exposure ratios of the metrics are quantified according to the relevant EMF limit values. For validation purposes, prototypes are fabricated, and SAR and incident power density are measured. The average difference between the numerical and experimental results is 0.4 dB for SAR and 0.9 dB for the incident power density, meaning that good agreement between simulations and measurements is obtained. The study provides valuable input for EMF as- sessment requirements and test methodologies for emerging technologies at or close to the transition frequency between different exposure metrics

Miniaturized Antenna Design For Wireless Biomedical Sensors

This thesis is focused on the design and simulation of miniaturized antennas for wireless biomedical sensors. The motivation of the work was to provide a solution for wireless systems that are embedded or placed on the body. Currently, small antennas are on demand to be implanted inside the body or placed closely to the body. The performance of such antennas, gain and efficiency, is affected by the lossy tissues that surround them. The goal of this work was to design antennas that are placed on a living body and integrated with a sensor system implanted in living tissue, to measure the dielectric properties of the tissue. The antenna type that this work was based on is Planar Inverted F Antenna (PIFA). The assumption was that the antenna is placed on skin layer and not embedded inside a tissue layers. A few antennas were designed and simulated. Two major studies were performed. First, an antenna, which was originally proposed in literature for wireless communication systems, was adopted and revised for biomedical applications. The antenna performance while it was on two tissue layers (skin and fat) was studied and optimized. The objective was to understand how miniaturization and the surrounding environment affect the antenna resonance frequency and performance. A second study was performed to design a novel PIFA antenna to improve the performance and reduce the size further

Investigation of dosimetry in four human head models for planar monopole antenna with a coupling feed for LTE/WWAN/WLAN internal mobile phone

The objective of the present study is to evaluate the Specific Absorption Rate (SAR) within the human head model exposed to the radiation of planar monopole antenna with T-shaped coupling feed and an inductive shorting strip. The presented design has a compact structure, a planar configuration and occupying a small size of 36×20mm2. Two wide bands can be generated by the proposed antenna 546 MHz (734-1280 MHz) and 1066 MHz (1934-3000 MHz) for the LTE/WWAN/WLAN internal mobile phone. The antenna performance parameters comprising return loss, radiation patterns, and gain are discussed. In this research work four different human head models have been implemented: homogenous spherical head, spherical seven layer model, Specific Anthropomorphic Mannequin (SAM) phantom and HUGO human head model. On the other hand the effects of operating frequency and gap distance between the mobile phone antenna and the human head model on distributions of the SAR inside the human head are investigated. All the simulations are done for three different distances between the antenna and the head model (5 mm, 10 mm and 20 mm). Moreover, the SAR levels for the head tissues are calculated in accordance to the two currently accepted standards: Federal Communications Commission (FCC) and International Commission on Non-Ionizing Radiation Protection (ICNIRP)

Design and Measurement-Based Evaluation of Multi-Antenna Mobile Terminals for LTE 3500 MHz Band

Design of multi-element antennas for small mobile terminals operating at higher frequencies remains challenging despite smaller antenna dimension and possibility of achieving electrically large separation between them. In this paper, the importance of the type of radiating elements operating at 3400-3600 MHz and their locations on the terminal chassis are highlighted. An isotropic radiation pattern that receives incoming signals from arbitrary directions is obtained by combining the radiation patterns of multiple antennas with localized chassis current distribution. Four multiport antennas configurations with two- and eight-element antennas are designed and evaluated experimentally in indoor propagation environments. Our proposed designs of multi-element antennas provide the highest MIMO channel capacity compared to their counterparts using antennas with less localized chassis current distribution, even in the presence of user's hand

Effects of hand on EM absorption and antenna performances for internal handset PIFA

Cilj ovog istraživanja je analizirati učinke ruke na elektromagnetsku (EM) apsorpciju i funkcioniranje antene. U radu se procjenjuje EM apsorpcija pomoću specifične brzine apsorpcije - specific absorption rate (SAR) u ljudskoj glavi i ukupne apsorbirane snage od strane korisnika. U radu se razmatraju parametri djelovanja antene uključujući učinkovitost zračenja, ukupnu učinkovitost, pojačanje i širinu frekvencijskog područja. Analiza je provedena pomoću mobilnog telefona položenog na obraz i s nagibom na obraz. Glavni dio istraživanja temelji se na finite-difference time-domain (FDTD) metodi. Rezultati pokazuju da su se SAR vrijednosti smanjile i da se ukupna snaga koju je korisnik apsorbirao brzo povećala zbog umetanja ručnog modela. Ruka korisnika također dovodi do znatnog smanjenja komunikacijskog učinka antene. Osim toga, predstavljena analiza daje neke korisne naznake za dizajn antene mobilnog telefona s obzirom na položaj ruke.The aim of this investigation is to analyse the effects of hand on electromagnetic (EM) absorption and antenna performances. The EM absorption is evaluated by using the specific absorption rate (SAR) in the human head and total absorbed power by the user in this paper. The antenna performance’s parameters comprising radiation efficiency, total efficiency, gain and bandwidth are considered in this investigation. The analysis was performed using mobile phone with a human head and hand model in both cheek and tilt positions. The main part of the investigation is based on the finite-difference time-domain (FDTD) method. The results show that the SAR values are decreased and total absorbed power by user increased rapidly due to insertion of hand model. The user’s hand also leads to degrade antenna’s communication performance considerably. Moreover, the presented analysis provides some useful indication to design handset antenna considering hand effects

Tunable decoupling and matching concepts for compact mobile terminal antennas

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Effects of hand on EM absorption and antenna performances for internal handset PIFA

Cilj ovog istraživanja je analizirati učinke ruke na elektromagnetsku (EM) apsorpciju i funkcioniranje antene. U radu se procjenjuje EM apsorpcija pomoću specifične brzine apsorpcije - specific absorption rate (SAR) u ljudskoj glavi i ukupne apsorbirane snage od strane korisnika. U radu se razmatraju parametri djelovanja antene uključujući učinkovitost zračenja, ukupnu učinkovitost, pojačanje i širinu frekvencijskog područja. Analiza je provedena pomoću mobilnog telefona položenog na obraz i s nagibom na obraz. Glavni dio istraživanja temelji se na finite-difference time-domain (FDTD) metodi. Rezultati pokazuju da su se SAR vrijednosti smanjile i da se ukupna snaga koju je korisnik apsorbirao brzo povećala zbog umetanja ručnog modela. Ruka korisnika također dovodi do znatnog smanjenja komunikacijskog učinka antene. Osim toga, predstavljena analiza daje neke korisne naznake za dizajn antene mobilnog telefona s obzirom na položaj ruke.The aim of this investigation is to analyse the effects of hand on electromagnetic (EM) absorption and antenna performances. The EM absorption is evaluated by using the specific absorption rate (SAR) in the human head and total absorbed power by the user in this paper. The antenna performance’s parameters comprising radiation efficiency, total efficiency, gain and bandwidth are considered in this investigation. The analysis was performed using mobile phone with a human head and hand model in both cheek and tilt positions. The main part of the investigation is based on the finite-difference time-domain (FDTD) method. The results show that the SAR values are decreased and total absorbed power by user increased rapidly due to insertion of hand model. The user’s hand also leads to degrade antenna’s communication performance considerably. Moreover, the presented analysis provides some useful indication to design handset antenna considering hand effects

The effect of jewellery and the human hand on SAR and antenna performance

This thesis investigates the effect of the human hand and metallic jewellery items worn on the human head and hand on SAR and on the antenna radiation patterns at 900 and 1900 MHz. The field excitation is provided by means of a A./4 monopole antenna on top of a metal box to emulate a simple handset. A planar inverted 'F' antenna (PIFA) is also used for comparison with the monopole. This thesis presents a detailed parametric study utilizing computer simulations via the Transmission Line Matrix (TLM) method and measurements from the DASY 4 SAR measurement system. Two different head and hand geometries are considered. Firstly a homogenous spherical head and block-hand were used in the simpler simulation, while the more realistic head and hand models were employed for the detailed study. The hand models include fingers which allow the metallic jewellery rings to be examined. The human hand has a significant effect on Specific Absorption Rate (SAR) and on the antenna pattern due to energy absorption and possible reflection at the hand dielectric boundary. In addition, the effects of different sizes, orientation, and distance of the metallic loop-like jewellery items relative to the antenna have been investigated. The metallic rings worn on the hand tend to reduce the SAR and could also alter the antenna radiation performance. The wrist worn bangle has very little effect on the results at the frequencies tested due to its position that is relatively far away from the handset antenna. The earrings could significantly influence the SAR and the radiation patterns, but the effects varied depending on the earring's diameter, its position relative to the head, the frequency and the type of antenna in use. The effect of the combination of the hand, the earring and the finger ring only show minor difference on the SAR values and on the antenna radiation patterns. Measurements of the effects of the hand and metallic jewellery items on SAR were performed inside a Standard anthropomorphic model (SAM) head phantom. A novel liquid hand phantom with realistic fingers has been manufactured, which allow the effect of metallic ring to be further investigated. Measurement results support the simulation results