Design considerations of MIMO antennas for mobile phones

YesThe paper presents a new modeling and design concept of antennas using polar- ization diversity of 2 £ 2 and 3 £ 3 Multiple Input Multiple Outputs (MIMO) system that is proposed for future mobile handsets. The channel capacity is investigated and discussed over Raleigh fading channel and compared to a linear/planner antenna array MIMO channel. The capacity is also discussed over three types of power azimuth spectrums. The results are compared to the constraints capacity limits in which the maximum capacity observed

A Frequence-Reconfigurable Tuner-Loaded Coupled-Fed Frame-Antenna for All- Metal-Shell Handsets

A frequency-reconfigurable frame-antenna integrated with a coupling strip and tuner loading is proposed for all-metal-shell mobile telephones. The coupling strip introduces additional capacitance to the feeding structure of the antenna, rendering the antenna to resonate at both the lower frequency band at "a quarter-wavelength resonant mode" and the higher frequency band at "a half-wavelength resonant mode". Moreover, the antenna loaded with a tuner achieves broadband frequency-reconfiguration by tuning the effective length of radiating frame. The antenna is designed by taking into consideration all the metallic components, like front-and-back cameras, telephone receiver, and a steel sheet. The metal-frame and metal-shell of the handset coupled with a strip are used as parts of the antenna. This paper of a prototype operating in a practical handset test environment shows that the proposed antenna is able to cover the bandwidth of 824-960 MHz (GSM) and 1710-2690 MHz (DCS/PCS/UMTS/LTE) with acceptable radiation efficiency up to 40% and desirable patterns and specific absorption ratio, which is much lower than 1.6 W/kg for mobile communications.11Ysciescopu

Käsipuhelinantennien miniatyrisointimenetelmät

Tässä diplomityössä tutkittiin pienten antennien miniatyrisointimenetelmiä. Tärkeimmät käsipuhelinantenneille asetetut vaatimukset ovat laajakaistaisuus, suuri säteilyhyötysuhde sekä pieni koko. Pienentämisen ongelma on näiden vaatimusten keskinäinen suhde; yhden ominaisuuden parantaminen tapahtuu aina jonkin toisen kustannuksella. Työssä havaittiin, että eri miniatyrisointimenetelmiä soveltamalla voidaan vaikuttaa em. ominaisuuksien jakautumiseen. Aluksi työssä käytiin lyhyesti läpi pienten antennien teoriaa sekä selvitettiin matkapuhelinantenneille asetettuja vaatimuksia. Seuraavaksi esiteltiin muutaman käsipuhelimen sisäiseksi antenniksi soveltuvan antennityypin ominaisuuksia. Käsitellyt antennityypit olivat dielektrinen resonaattoriantenni ja PIFA-antenni (mikroliuska-antenni). Tämän jälkeen tutkittiin eri miniatyrisointitekniikoita ja niiden soveltamista edellä esiteltyihin antennityyppeihin. Useita antenneja tutkittiin kokeellisesti. Tavallisten impedanssi- ja säteilyominaisuuksien lisäksi mitattiin prototyyppien säteilyhyötysuhteet. Miniatyrisointi dielektrisesti kuormittamalla todettiin tehokkaaksi dielektristen resonaattoriantennien yhteydessä, mutta työssä toteutetulle erittäin ohuelle mikroliuska-antennille, jossa on enemmän metalliosia, tämä menetelmä ei sovi. Korkeapermittiivisen materiaalin lisääminen tällaiseen rakenteeseen heikensi antennin säteilyominaisuuksia aiheuttaen metallihäviöiden suhteellisen osuuden voimakkaan kasvun. Tämä johti hyvin huonoon hyötysuhteeseen. PlFA-antennin resistiivinen kuormittaminen lisäsi huomattavasti kaistanleveyttä, mutta tämä tapahtui selvästi säteilytehokkuuden kustannuksella. Muut PIFA-antenneille sovelletut menetelmät huomattiin kokonaisvaikutuksiltaan melko yhdenvertaisiksi. Reaktiivisesti kuormittamalla saavutettiin korkea säteilyhyötysuhde, mutta antennin koon pienentyessä menetettiin samalla kaistanleveyttä. Sama ilmiö havaittiin hidasaaltorakenteissa

Design of 2x2 U-shape MIMO slot antennas with EBG material for mobile handset applications.

yesA compact dual U-shaped slot PIFA antenna with Electromagnetic Bandgap (EBG) material on a relatively low dielectric constant substrate is presented. Periodic structures have found to reduce mutual coupling and decrease the separation of antenna and ground plane. A design with EGB material suitable for a small terminal mobile handset operating at 2.4 GHz was studied. Simulated and measured scattering parameters are compared for U-shaped slot PIFA antenna with and without EBG structures. An evaluation of MIMO antennas is presented, with analysis of the mutual coupling, correlation coefficient, total active reflection coefficient (TARC), channel capacity and capacity loss. The proposed antenna meets the requirements for practical application within a mobile handset.Electronics and Telecommunication

Miniaturized DGS and EBG structures for decoupling multiple antennas on compact wireless terminals

MIMO (Multiple Input Multiple Output) technology has been presented to significantly increase the wireless channel capacity and reliability without requiring additional radio spectrum or power. In MIMO systems, multiple antennas are mounted at both the transmitter and the receiver. When this technology is employed for a compact wireless terminal, one of the most challenging tasks is to reduce the high mutual coupling between closely placed antenna array elements. The high mutual coupling produces high correlation between antenna elements and affects the channel capacity of MIMO system. The objectives of this thesis are to design practical miniaturized structures to reduce high mutual coupling for small wireless terminals. The research is conducted in the following areas. Initially, a PIFA design and two-element PIFA array are proposed and optimized to operate at 1.9GHz. A pair of two coupled quarter-wavelength linear slits is inserted in a compact ground plane, resulting in significant reduction of the mutual coupling across antenna operating frequency band. In order to take up less space on the ground plane, instead of the linear slits, miniaturized convoluted slits are implemented between the two closely placed PIFAs. Although the convoluted slits have small area and are positioned close to the edges of the ground plane, the miniaturized convoluted slit structures achieve a reduction of mutual coupling between antenna elements and succeed in reducing the effect of the human body (head and hand) to the antennas. In order to further reduce the size of the slits etched on the compact ground plane, a novel double-layer slit-patch EBG structure is proposed. It consists of a two-layer structure including conducting patches and aperture slits placed on either side of a very thin dielectric layer. They are placed in very close proximity to each other (55μm). A two-element printed CPW-fed monopole array operating around 2.46GHz and a two-element UWB planar monopole array operating from 3GHz to 6GHz have been employed to investigate the proposed slit-patch EBG structures. The optimized double-layer slit-patch EBG structure yields a significant reduction of the mutual coupling and produces the maximum miniaturization of antenna array. Another novel convoluted slit-patch EBG structure has been presented to reduce the mutual coupling between two PIFAs operating at 1.9GHz. These results demonstrate that the slit-patch EBG structure is a feasible technology to reduce the mutual coupling between multiple antennas for compact wireless terminals

Recovering handset diversity and MIMO capacity with polarization-agile antennas

Journal ArticleDesign guidance is provided for multiple-input-multiple- output (MIMO) antenna systems on handsets-a strong prospect for next generation wireless devices. Handheld wireless devices are likely to be rotated out of their optimal polarization, thereby experiencing significant power losses. An existing polarization-agile antenna design and a novel four-spoke extension recover significant fractions of the rotation-induced losses both in switched-antenna diversity and capacity calculations-all but 1 dB of diversity gains at a 99% system reliability, half of the CΕ losses or 80% of the Cο,1 losses. These gains benefit four- and ten-element arrays and remain significant in the presence of 6 dB cross coupling and in volume-restricted arrays. Diversity order investigations also demonstrate a new, non-Rayleigh locus of curves describing patch antennas subject to rotation