MIMO Systems and Antennas for Terminals

Li, Hui; Lau, Buon Kiong

doi:10.1007/978-981-4560-75-7_99-1

Cited by 7 publications

(4 citation statements)

References 91 publications

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“…Implementing more than one antenna port per band for MIMO operation is challenging in user terminals, especially in frequency bands below 1 GHz, due to their compact form factor [2]. The small electrical size of the terminal chassis offers limited degrees of freedom (in terms of the number of resonant modes) to fulfill strict requirements of orthogonal MIMO antenna and wideband design.…”

Section: A Mimo Terminal Antenna Design Challengesmentioning

confidence: 99%

“…This is because MIMO systems (e.g., LTE) are typically used in rich multipath environments, where the angular power spectrum of the outgoing or incoming signal is nearly uniform. In such a propagation environment, orthogonal patterns of MIMO antenna elements are sufficient to guarantee uncorrelated signals across the antenna ports [2]. Therefore, as long as each antenna port excites one or more than one unique modes, with no mode being excited by more than one port, all the resulting patterns will be pairwise uncorrelated, as illustrated by (2), and likewise the received signals at antenna ports will be pairwise uncorrelated.…”

Section: Mimo Analysis Using Characteristic Mode Theorymentioning

confidence: 99%

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Low-Profile Two-Port MIMO Terminal Antenna for Low LTE Bands With Wideband Multimodal Excitation

Aliakbari

Lau

2020

IEEE Open J. Antennas Propag.

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Multiple-input multiple-output (MIMO) is a key enabler for high data rates in mobile communications. However, it is challenging to design MIMO terminal antennas for LTE bands below 1 GHz, due to the conventional chassis offering only one resonant characteristic mode (CM). Recently, it was shown that minor structural changes can yield up to two additional resonant modes for designing two-port MIMO antennas. Nonetheless, the resulting bandwidth for the second port is relatively small. To simultaneously meet bandwidth and other practical requirements (including low profile and no off-ground clearance), a step-by-step approach for structural changes and feed design is applied in this work to exemplify the use of physical insights from CM analysis to achieve a competitive wideband two-port solution. The main novelty is that an entirely new mode is identified and appropriately tuned by structural modification for creating an additional resonance below 1 GHz. Moreover, two simple probe-feed ports are designed to jointly excite different subsets of four modes over frequency. In addition, far-field pattern orthogonality is guaranteed by the different phase shifts of the characteristic electric fields at the port locations. Furthermore, bulkier self-resonant antenna elements are avoided. To show design flexibility, a three-port version is also demonstrated.

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Section: A Mimo Terminal Antenna Design Challengesmentioning

confidence: 99%

Section: Mimo Analysis Using Characteristic Mode Theorymentioning

confidence: 99%

Low-Profile Two-Port MIMO Terminal Antenna for Low LTE Bands With Wideband Multimodal Excitation

Aliakbari

Lau

2020

IEEE Open J. Antennas Propag.

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“…It is in widespread use in Long Term Evolution (LTE), IEEE 802.11ac and other wireless communication systems [1]. However, implementing more than one antenna per band in user terminals is challenging in mobile communications, especially in frequency bands below 1 GHz, due to their compact form factor [2]. The small electrical size of the terminal chassis offers limited degrees of freedom (in terms of the number of resonant modes) to fulfill strict requirements of orthogonal MIMO antenna and wideband design.…”

Section: Introductionmentioning

confidence: 99%

Low-Profile Two-Port MIMO Terminal Antenna for Low LTE Bands with Wideband Multimodal Excitation

Aliakbari¹,

Lau²

2020

Preprint

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It is challenging to design multiple-input multiple-output (MIMO) terminal antennas for LTE bands below 1 GHz, due to the conventional chassis offering only one resonant characteristic mode. Recently, it was shown that minor structural changes can yield additional resonant mode(s), which were used to design two-port MIMO antennas. However, the resulting bandwidth for the second port does not cover the low LTE bands. Herein, a new approach to structural changes and feed design is proposed for the design of a low profile (4 mm) two-port MIMO antenna that covers all common low LTE bands (0.75-0.96 GHz) with total efficiency of above 67%. The large symmetric bandwidth (25%) is achieved using three additional resonant modes obtained by structural changes as well as two simple probe-feed ports jointly exciting weighted combinations of the four modes over frequency. The envelope correlation coefficient of below 0.15 is facilitated by the different phase shifts of the characteristic electric fields at the port locations. Moreover, the design requires no ground clearance, no decoupling structure and the two ports are separated by only 0.2 wavelength. Finally, to show design flexibility, a third antenna is added to the top of the chassis to create a three-port MIMO antenna

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“…Multiple-input multiple-out (MIMO) technology is very popular due to its ability to provide high spectral efficiency in wireless communications [1]. However, to implement MIMO in terminal antennas is challenging, as their compact form factor leads to the multi-antennas being placed in close proximity to one another [2]. Moreover, at frequencies below 1 GHz, the terminal chassis can only provide one resonant characteristic mode (CM), which limits the ability of multiantennas to simultaneous provide sufficient bandwidth and isolation for practical mobile applications [3].…”

Section: Introductionmentioning

confidence: 99%

Enhanced Low Band MIMO Terminal Antenna Based on Selective Feeding of Chassis Modes

Aliakbari

Liang

Lau

2020

2020 14th European Conference on Antennas and Propagation (EuCAP)

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Multiple-input multiple-out (MIMO) is a mature technology in modern wireless communications. However, it is challenging to implement multi-antennas for MIMO operation in compact mobile terminals, due to high mutual coupling and correlation among closely spaced antenna elements. Moreover, a conventional terminal chassis only offers one resonant mode below 1 GHz, complicating multi-antenna design. Recently, it has been shown that the chassis can be modified to facilitate a few resonant modes below 1 GHz. However, attempts to excite these modes selectively using a single coupling feed per antenna port result in limited bandwidth and isolation. In this work, we propose dual-feed antenna ports to improve selective feeding of the resonant modes of an existing two-port MIMO terminal antenna below 1 GHz. Simulation results reveal significantly enhanced bandwidths of 30% and 15% for the two ports, as well as high isolation of over 32 dB.

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MIMO Systems and Antennas for Terminals

Cited by 7 publications

References 91 publications

Low-Profile Two-Port MIMO Terminal Antenna for Low LTE Bands With Wideband Multimodal Excitation

Low-Profile Two-Port MIMO Terminal Antenna for Low LTE Bands With Wideband Multimodal Excitation

Low-Profile Two-Port MIMO Terminal Antenna for Low LTE Bands with Wideband Multimodal Excitation

Enhanced Low Band MIMO Terminal Antenna Based on Selective Feeding of Chassis Modes

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