Dual-band MIMO antenna using double-T structure for WLAN applications

Session - Interactive 2.3: Multi-Band AntennasThe Conference program's website is located at http://www.iwat2014.org/index.php/program/detailed-programA dual-band multiple-input-multiple-output (MIMO) antenna is proposed for the wireless-local-area-network (WLAN) applications in the 2.4-GHz and 5.2-GHz bands. The antenna consists of two double-T monopole elements with microstrip-fed and symmetrically placed on a substrate. To enhance isolation between the two monopole elements, three slots are cut on the ground plane on the other side of the substrate. The longer slot is used for better isolation in the 2.4-GHz band, while the two shorter slots are used for the 5.2-GHz band. Simulation and measurement are used to study the antenna performance in terms of S parameters, radiation patterns, realized gain, efficiency, and envelope correlation coefficient. Results show that the MIMO antenna has the two operation bands of 2.20-2.75 GHz and 5.09-5.50 GHz with mutual coupling of less than -15 dB and envelope correlation coefficient of less than 0.1, making it a good candidate for WLAN applications.published_or_final_versio

Performance of a multiband diversity antenna with hand effects

The implementation of multiband diversity antennas in compact mobile handsets, for the purpose of increasing transmission quality, is a topic of current interest in the mobile phone industry. In order to achieve the expected performance improvement in typical operating conditions, we not only have to contend with the challenges of designing multiple multiband antennas, which are closely spaced within the compact handset and thus strongly interacting with one another electromagnetically [1], we also need to keep in check the electromagnetic interaction between the whole antenna system (i.e., the handset) and the user. Previous studies have concluded that the presence of a user degrades the mean effective gain (MEG) of the diversity antennas significantly [1]-[3]. Different results have been presented on the effect of the user on the correlation coefficient, no effect [1] and a significant increase of the correlation [2], [3], have been pointed out. However, these studies have been performed on simple single band antennas in talk position. In this paper a more realistic approach is presented by choosing the diversity antenna system to comprise compact versions of PIFA and monopole antennas which cover three WCDMA bands: WCDMA850, WCDMA1800 and UMTS [4]. Such compact antennas are easily conformable for small mobile phone products [4]. The choice of the bands, as well as the evaluation of the diversity performance for the data mode position, is derived from the increasing demand on HSDPA applications in the mobile phone market. The investigation of user interaction presented in this paper focuses on the comparison between the free space and data mode diversity performance of a tri-band “stick” phone size prototype in the uniform 3D propagation environment. A state-of-the-art phantom hand from IndexSAR [5] is used to hold the diversity prototype in the data mode position

Ultra-compact dual-polarised UWB MIMO antenna with meandered feeding lines

An ultra-compact dual-polarised ultra-wideband multi-input multi-output antenna made with a single-shared-radiating element and two meandered feeding lines are proposed. Miniaturisation is achieved by using a combination of techniques, including a resonant stub connected to the ground through which shorts the excessive coupled energy before it reaches the other port and minimises coupling, slots etched in the radiator that also help minimise mutual coupling, while the meandered lines allow to bring the antenna closer to the greatly reduce the overall size of the antenna. Slots etched in the radiator and the use of a stub connected to the ground through, help to minimise the mutual coupling. The formation of orthogonal surface currents provides the necessary dual polarisation. Simulated and measured results demonstrate the wideband impedance matching, low mutual coupling and low envelope correlation coefficient. This antenna has an extremely compact size (22 7 24.3 mm2, including the ground plane) that makes it an excellent candidate for portable and handheld devices. \ua9 The Institution of Engineering and Technology

Compact MIMO antenna for portable devices in UWB applications

A compact multiple-input-multiple-output (MIMO) antenna with a small size of 26× 40mm2 is proposed for portable ultrawideband (UWB) applications. The antenna consists of two planar-monopole (PM) antenna elements with microstrip-fed printed on one side of the substrate and placed perpendicularly to each other to achieve good isolation. To enhance isolation and increase impedance bandwidth, two long protruding ground stubs are added to the ground plane on the other side and a short ground strip is used to connect the ground planes of the two PMs together to form a common ground. Simulation and measurement are used to study the antenna performance in terms of reflection coefficients at the two input ports, coupling between the two input ports, radiation pattern, realized peak gain, efficiency and envelope correlation coefficient for pattern diversity. Results show that the MIMO antenna has an impedance bandwidth of larger than 3.1-10.6 GHz, low mutual coupling of less than-15 dB, and a low envelope correlation coefficient of less than 0.2 across the frequency band, making it a good candidate for portable UWB applications. © 2013 IEEE.published_or_final_versio

Frequency-Reconfigurable MIMO Monopole Antenna with Wide-Continuous Tuning Range

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Mutual coupling reduction of two PIFAs with a T-shape slot impedance transformer for MIMO mobile terminals

Abstract in UndeterminedAn efficient technique is introduced to reduce mutual coupling between two closely spaced PIFAs for MIMO mobile terminals. The proposed mutual coupling reduction method is based on a T-shape slot impedance transformer and can be applied to both single-band and dual-band PIFAs. For the proposed single-band dual PIFAs, the 10 dB impedance bandwidth covers the 2.4 GHz WLAN band (2.4–2.48 GHz), and within the WLAN band an isolation of over 20 dB is achieved. Moreover, the dual-band version covers both the WLAN band and the WiMAX band of 3.4–3.6 GHz, with isolations of over 19.2 dB and 22.8 dB, respectively. The efficiency, gain and radiation patterns of the two-PIFA prototypes are verified in measurements. Due to very low pattern correlation and very good matching and isolation characteristics, the capacity performances are mainly limited by radiation efficiency. The single-band and dual-band PIFAs are also studied with respect to their locations on the ground plane. An eight-fold increase in the bandwidth of one PIFA is achieved, when the single-band PIFAs are positioned at one corner of the ground plane, with the bandwidth of the other PIFA and the good isolation unchanged

Actual diversity performance of a multiband diversity antenna with hand and head effects

Using the metric actual diversity gain (ADG), diversity performance is investigated for a compact mobile terminal prototype with two internal, triple frequency band antennas in four different cases of user interaction. ADG is presented as a preferred alternative to apparent diversity gain and effective diversity gain. Absorption due to user proximity causes degradation and imbalance in mean effective gain of the antennas over the frequency bands, contributing to a degradation in diversity performance. However, user-induced changes in the antenna patterns cause a decrease in correlation in the low frequency band, which facilitates increased diversity gain. The study reveals that a significant net diversity gain, i.e., ADG of 5-8 dB compared to a single antenna prototype, can be achieved using multiband antennas in the proximity of a user, even at low frequencies for antennas with high mutual coupling