Proposed Multiple-input Multiple-output Antenna Research Articles

인체부착형 Headset MIMO 안테나 설계

본 논문에서는 인체부착형 Headset MIMO(Multiple-Input Multiple-Output) 안테나를 제안하고, 인체의 영향을 고려한 안테나 성능과 인체에 미칠 수 있는 영향에 대한 분석을 하였다. 제안된 MIMO 안테나는 접지면 위에 PIFA(planar inverted-F antenna) 형태의 두 안테나와 격리도 특성 개선을 위하여 안테나 사이에 위치한 isolator로 구성되어 있다. 근거리장에 인체가 존재할 때 안테나에 미치는 영향을 분석하기 위하여 시뮬레이션을 수행하고, 팬텀을 이용하여 시뮬레이션과 측정을 하였다. 측정 결과, MIMO 안테나의 성능을 평가하는 파라미터 중 하나인 상관 계수(Envelope Correlation Coefficient: ECC)는 ISM 대역에서 0.1 이하의 값을 가지므로 제안된 MIMO 안테나의 diversity 성능이 우수함을 입증하였다. 또한, 측정된 SAR(Specific Absorption Rate) 값은 공급전력 250 mW에서 안테나 1, 2 각각 0.575, 0.571 W/kg이었다. 이는 1 g 평균 전자파 흡수율을 1.6 W/kg으로 제한한 FCC의 지침을 초과하지 않음을 알 수 있다. 따라서 제안된 인체부착형 Headset MIMO 안테나는 실용이 가능할 것으로 기대된다. In this paper, a headset multiple-input multiple-output(MIMO) antenna for on-body application is proposed and the antenna performance with body effect and the impact on human body are investigated. The proposed MIMO antenna is composed of two planar inverted-F antennas(PIFA) above ground plane and an isolator located between the two antennas enhance the isolation characteristic. Simulation was carried to analyze the effect of human body on antenna performance when a human body is located in the near field of the antenna. According to the measurement result, the diversity performance of the proposed antenna can be considered good since ECC(Envelope Correlation Coefficient), which commonly indicates the performance of a MIMO antenna, remains below 0.1 over the ISM band. The measured SAR values for antennas 1 and 2 are 0.575 W/kg and 0.571 W/kg, respectively when 250 mW input power in engaged. These values satisfy the FCC guideline which states that the 1-g average SAR should be lower than 1.6 W/kg.

Dual-band MIMO antenna using polarization diversity for 4G mobile handset application

A dual-band multiple-input multiple-output (MIMO) antenna using polarization diversity is proposed for a 4G mobile handset application.The proposed MIMO antenna consists of two printed dual-band PIFAs with a slotted strip. Input port 1 of the first PIFA is orthogonally disposed with respect to input port 2 of the second PIFA. The orthogonal placement of the two feed points ensures that the dominant polarization of each of the PIFAs is opposite to each other, resulting in a good isolation performance. The proposed MIMO antenna has an isolation of ∼17 dB at LTE band 13, and the envelope correlation coefficient (ECC) of the two antennas is always lower than 0.4 over all of LTE band 13. To evaluate the performance of the proposed antenna, key performance parameters such as the total efficiency, ECC, mean effective gain (MEG), MEG ratio, and actual diversity gain are analyzed. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26197

TRI-BAND FOUR-ELEMENT MIMO ANTENNA WITH HIGH ISOLATION

A tri-band four-element MIMO (multiple-input-multiple- output) antenna with high isolation is presented. The MIMO antenna consists of four symmetrical antenna elements. To relieve the degradation of the operation bandwidth caused by the strong mutual coupling among the four antenna elements, four symmetrical rectangles are removed from the four corners of the ground plane, respectively. The efiect of the cutting of the four rectangles on the isolation is slight. Two kinds of isolation structure are applied to reduce the mutual coupling among the elements. The flrst kind of isolation consists of two slits and a protruded ground branch, and the second kind of isolation structure consists of four symmetrical slits etched into the ground plane. The mutual coupling caused by surface currents is reduced by slits, the mutual coupling resulted from near-fleld is suppressed by the ground branches, and thus high isolation for the MIMO antenna is achieved. Moreover, the efiects of the slits and the ground branches on the operation bandwidth are slight, thus the operation bandwidth and the mutual coupling can be controlled independently, to some degree. A tri-band operation bandwidth (2.34{2.95GHz, 3.38{3.75GHz, and 4.4{6.7GHz) with VSWR • 2 and isolation ‚ 20dB, is achieved. The results, including S-parameters, radiation patterns, mean efiective gain (MEG), radiation e-ciency and signal correlations, indicate that the proposed MIMO antenna can provide spatial or pattern diversity to increase data capacity of wireless communication systems.

Small-size printed strip MIMO antenna for next generation mobile handset application

A compact printed multiple-input multiple-output (MIMO) antenna with an embedded chip inductor is proposed for a 4G mobile handset application. The proposed MIMO antenna consists of a longer strip with an embedded chip inductor and a shorter radiating strip. The longer radiating strip with a 15-nH embedded chip inductor has a length of only about 42 mm (∼ 0.1 wavelength at 0.77 GHz), but it supports a wide resonant mode at 0.77 GHz for long-term evolution (LTE) Band 13 and at 2.35 GHz for WiBro operation. The shorter radiating strip has a length of about 15 mm (about 0.1 wavelength at 2.0 GHz) and provides a wide resonant mode at about 2 GHz for WCDMA operation. The two radiating strips occupy a small printed area of about 720 mm2 on the system circuit board of a mobile handset. The proposed MIMO antenna has an isolation of approximately −17 dB at LTE band 13 and the envelope correlation coefficient (ECC) of the two antennas is always lower than 0.4 over the whole LTE band 13. To evaluate the performance of the proposed antenna, key performance parameters such as the total efficiency, ECC, mean effective gain (MEG), and the MEG ratio are analyzed. © 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 53:348–352, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.25746

Three‐antenna MIMO system for WLAN operation in a PDA phone

AbstractA multiple input multiple output (MIMO) system using three EMC (electromagnetic compatible) chip antennas in a personal digital assistant (PDA) phone is demonstrated. The three EMC chip antennas are mounted at three corners of the system ground plane of the PDA phone and all generate a wide bandwidth covering the wireless local area network (WLAN) operation in the 2.4‐GHz band (2400–2484 MHz). By adding a T‐shaped shorted strip in the proposed MIMO antenna system, large improvements in the isolation (S12, S13, and S23 all less than −20 dB) between any two antennas of the MIMO system are achieved. Detailed effects of the T‐shaped shorted strip on the isolation improvement in the proposed MIMO antenna system are analyzed. Radiation characteristics of the three antennas are also studied. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 1238–1242, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21665