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.

User’s hand effect on efficiency of 2-port 5 GHZ mobile terminal antennas

In this paper, the influence of user’s hand on mobile terminal antenna when it placed approximately on top of Multiple Input Multiple Output radiating element antennas (PIFAs) is studied extensively. The antenna is designed to operate at 5 GHz with 1.5 GHz of -6 dB bandwidth. The effect of user’s hand with different finger positions are studied at seven positions on slit at the ground plane, seven differences height above the antenna and nine different locations around the radiating element at 2 mm height from antenna. The losses due to presence of hand are studied in terms of scattering parameters, radiation efficiency and matching efficiency. The maximum loss in term of isolation in the presence of user’s hand is found at 6 mm on the slit and it decreased as the hand move away from the slitted area on the ground plane. The maximum efficiency loss is observed when the finger is placed right on top of the radiating element with -5.85 dB compare to antenna without the presence of user’s hand. On the other hand, the result for matching efficiency indicates approximately 0.2 dB losses occurred when the fingers are varied at different height and position

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

Investigation into Low SAR PIFA Antenna and Design a Very Low SAR U-slot Antenna using Frequency Selective Surface for cell-phones and Wearable Applications

There are very important questions. “Do Electromagnetic waves have irreparable effects on human or not?” “Are there any relation between cancer and waves?” and finally “what should we do to be safe?”. In the present article, these questions will be answered simply and professionally. First of all, Specific Absorption rate (SAR) is define then L-Slot and U-slot antenna is designed and simulated using cell-phones and wearable applications, operating at  and  consist of GSM900 and GSM1800. Standard frequency band width for the first and second band is  and  for uplink and downlink and in the present research these numbers are obtained. The SAR of each antenna is measured and is compared with each other. Thanks to design of antenna, The SAR of U-Slot antenna is very low and it is almost stimulated  and this sentence means this antenna is anti-cancer. Finally, Some SRR unit-cells are designed and when they are used in structure, SAR will be more decrease. Last SAR value is  and  for each bands .In the last table, There are some comparison between different creditable references and present article SAR reduction is acceptable and it is near to  percentage

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

Ultra-broadband antenna with robustness to body detuning for 4G eyewear devices

An ultra-broadband antenna design for 4G cellular coverage in eyewear devices is presented in this paper. The antenna has been designed considering a realistic eyewear PCB and its dielectric frame. In order to overcome any negative effects from the antenna's surroundings (frequency detuning due to the head and the hand of the user), the antenna was designed to cover continuously the 700-2700 MHz band with a reflection coefficient below -6 dB instead of a dual-band behavior usually required for 4G operation: 700-960 MHz and 1700-2700 MHz. The antenna was of capacitive coupling element type with its appropriate matching network to cover the mentioned frequency interval. To emulate a realistic device, an ABS plastic dielectric frame was manufactured using 3D-printing technology. The antenna was simulated and tested in three different use-cases as: "default case with user's head", "with head and hand" and "free space" cases. State-of-the art performance is demonstrated. The specific absorption rate (SAR) behavior was also investigated through simulations and measurements to check the compliance with regulations

Fixed and reconfigurable multiband antennas

This thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel UniversityWith the current scenario of development of antennas in the wireless communication field, the need of compact multiband, multifunctional and cost effective antenna is on the rise. The objective of this thesis is to present fixed and reconfigurable techniques and methods for small and slim multiband antennas, which are applicable to serve modern small and slime wireless, mobile and cognitive radio applications. In the fixed designs, independent control of the operating frequencies is investigated to enhance the antennas capabilities and to give the designer an additional level of freedom to design the antenna for other bands easily without altering the shape or the size of the antenna. In addition, for mobile phone antenna, the effect of user’s hand and mobile phone housing are studied to be with minimum effect. Although fixed multiband antennas can widely be used in many different systems or devices, they lack flexibility to accommodate new services compared with reconfigurable antennas. A reconfigurable antenna can be considered as one of the key advances for future wireless communication transceivers. The advantage of using a reconfigurable antenna is to operate in multiband where the total antenna volume can be reused and therefore the overall size can be reduced. Moreover, the future of cell phones and other personal mobile devices require compact multiband antennas and smart antennas with reconfigurable features. Two different types of frequency reconfigurability are investigated in this thesis: switchable and tunable. In the switchable reconfigurability, PIN diodes have been used so the antenna’s operating frequencies can hop between different services whereas varactor diode with variable capacitance allow the antenna’s operating frequencies to be fine-tuned over the operating bands. With this in mind, firstly, a switchable compact and slim antenna with two patch elements is presented for cognitive radio applications where the antenna is capable of operating in wideband and narrow bands depending on the states of the switches. In addition to this, a switchable design is proposed to switch between single, dual and tri bands applications (using a single varactor diode to act as a switch at lower capacitance values) with some fine tuning capabilities for the first and third bands when the capacitance of the diode is further increased. Secondly, the earlier designed fixed antennas are modified to be reconfigurable with fine-tuning so that they can be used for more applications in both wireless and mobile applications with the ability to control the bands simultaneously or independently over a wide range. Both analytical and numerical methods are used to implement a realistic and functional design. Parametric analyses using simulation tools are performed to study critical parameters that may affect the designs. Finally, the simulated designs are fabricated, and measured results are presented that validate the design approaches