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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 effect 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 first 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-field is suppressed by the ground branches, and thus high isolation for the MIMO antenna is achieved. Moreover, the effects 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 (2.34-2.95 GHz, 3.38-3.75 GHz, and 4.4-6.7 GHz) with VSWR ≤ 2 and isolation ≥ 20 dB, is achieved. The results, including S-parameters, radiation patterns, mean effective gain (MEG), radiation efficiency and signal correlations, indicate that the proposed MIMO antenna can provide spatial or pattern diversity to increase data capacity of wireless communication systems. [ABSTRACT FROM AUTHOR]

A compact dual-band multiple-input-multiple-output (MIMO) antenna is presented. The MIMO antenna consists of two orthogonal elements with edge-to-edge separation of nearly 0.047λ0 at 2.0 GHz, and the element is two-strip structure which can help to improve the impedance matching and isolation. Result shows a dual-band of 76% from 1.62 to 3.6 GHz and 28.5% from 4.44 to 5.92 GHz. The MIMO antenna has strong robust property to the nearby conducting elements, and that is an advantage over the conventional MIMO antennas. The mean effective gain (MEG), radiation efficiency, correlation coefficient, and effective diversity gain (EDG) are calculated to evaluate the diversity performance of the MIMO antenna. To provide quantifications for the performance of the MIMO antenna in real-world usage condition, effects of human hand and head on radiation efficiency and total radiated power (TRP) are investigated. The results indicate the antenna serving as a phone antenna can provide spatial and pattern diversity to combat multipath fading. [ABSTRACT FROM AUTHOR]

A printed antenna having a low profile and a broad bandwidth is presented. The antenna consists of a loop structure constructed with two-layered meander strips. The loop structure and meander strips are used to enhance the impedance bandwidth and reduce the antenna size, respectively. A prototype of the proposed antenna with a small antenna height of 5 mm is constructed and tested. The measured results show that the antenna has a bandwidth of 30.2% (643 MHz) according to -10 dB return loss in 2.1 GHz band. In addition, effects of the main geometrical parameters on the performance of the antenna are also investigated. [ABSTRACT FROM AUTHOR]

This paper presents a novel low-profile bifilar spherical helical antenna, which is a partition detruncated from the bifilar spherical helical antenna with constant ratio between adjacent two helixes. Radiation properties of the antennas are calculated and measured, results of which indicate that this antenna can provide a directivity of > 6 dB and an axial ratio of < 3 dB over a very wide band. The radiation patterns have broad beam and 20 dB front-to-back ratio, showing that it is of great value in satellite communication applications. [ABSTRACT FROM AUTHOR]

A novel swallow-tailed wideband planar monopole antenna with semi-elliptical base is presented. The impedance and radiation properties of the proposed monopole antenna are investigated experimentally. The study indicates that the proposed monopole antenna yields the maximum bandwidth from 1.22 GHz to more than 15 GHz for VSWR<2 with the optimum ellipticity ratio of the antenna's semi-elliptical base and the height of the feeding post. The radiation performance is also discussed and shown to be acceptable over a wide frequency range. [ABSTRACT FROM AUTHOR]

A two-element ultra wideband array antenna with a 5.8 GHz band-notch function is proposed. A novel Marchand balun feeding structure is chosen for its great merit of the equi-amplitude and 180° phase difference signals, making the omni-directional of radiation pattern much better. A simple u-shape slot is inserted into the radiating patch to create a frequency band-stop characteristic. The measured VSWR less than 2 is from 3.1 to 10.6 GHz, and the frequency notch band is from 5.7 to 5.9 GHz. The measured results agree well with the simulated. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 1537–1539, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24384 [ABSTRACT FROM AUTHOR]

A low profile antenna, with polarisation diversity, for operation in a tyre pressure monitoring system (TPMS), is investigated. By combining the signals received from the two ports in phase or 180° out of phase, the antenna can operate at two different modes: a top-loaded monopole antenna and a planar dipole antenna located very close to a conducting plane (about 0.028 λ). Two significant techniques are used to enhance impedance bandwidth and to reduce antenna length. A prototype is implemented and the results obtained are given. [ABSTRACT FROM AUTHOR]

A novel dual-band toroidal beam antenna for wireless local area network (WLAN) communications is presented. The antenna mainly consists of six dual-band inverted-L radiating elements and a two-section six-way microstrip power divider. By inserting slots into the radiating elements, two resonant frequencies are achieved at WLAN bands. By using the two-section six-way power divider, the six radiating elements are excited with equal amplitude and phase at the two working frequency bands. A prototype has been constructed and tested. Good toroidal beam radiation patterns for 2.4 and 5.2 GHz bands are obtained. [ABSTRACT FROM AUTHOR]

A novel planar meander sleeve monopole antenna for digital video broadcasting-hand held (DVB-H) and GSM mobile handsets is presented. By using the planar sleeve monopole type radiating element constructed with meander strips, the antenna provides a degree of miniaturisation while retaining a wide bandwidth covering the DVB-H and GSM-900 bands. A prototype is constructed and tested, which shows that an impedance bandwidth of 498 MHz (463–961 MHz) within 2.5:1 VSWR is achieved. [ABSTRACT FROM AUTHOR]