| The antenna is one of the necessary components in the wireless communication system, it imposes a important effect on the performance of the whole system. With the rapid development of wireless communication system, we require the terminal antenna be capable to provide more function. Therefore, It is crucial and practical to research the antenna operating at multiple bands or possessing wide bandwiths which is suitable for different applications and the MIMO antenna which is composed of several elements achieving high data rate and gain improvement. This paper focuses on the design of multiband or wideband MIMO antenna.Firstly, an overview of the development of multiband or ultrawideband MIMO antenna is introduced, subsequently the corresponding technologies are summarized.Secondly, the working mechanism and fundamental parameters of the antenna are proposed.Finally, several multiband or wideband MIMO antennas for WLAN/Wi MAX applications are presented.1. A compact printed dual-band antenna for Wi MAX/WLAN applications is proposed. The dual-band monopole antenna consists of a triangular patch and two folding arms shorted to the ground plane. The proposed antenna features a low profile and compact dimension. To avoid via process in the fabrication, the triangular patch and two folding arms are separately constructed on the two sides of a FR4 substrate. By employing this structure, five different resonances can be yielded. The triangular patch provides two resonant modes(4.62 GHz and 7.05 GHz). The two folding arms produces three resonances at 2.43 GHz, 3.43 GHz, and 6.59 GHz. The measured-10 d B return loss is given as follows: 2.39–2.54 GHz and 3.39–7.49 GHz.2. A concise printed dual-band MIMO antenna for WLAN/Wi MAX application is developed. The sizes of dual-band MIMO antenna is 31 × 31 mm2. The concise MIMO antenna consists of two symmetrical antenna elements. Each antenna element consists of three branches. which are responsible for three resonance points, and the three resonance points form the desired operation band covering 2.4/3.5/5.5 GHz bands. A U shape decoupling structure with four implanted branches not only forms good isolation between two antenna elements(S21 below-18 d B in the full operation band), but also improves the impedance bandwidth greatly.3. A compact printed wideband MIMO antenna is developed. The proposed MIMO antenna structure, which consists of two symmetric monopoles element, is printed parallel on a printed circuit board. The antenna is designed to cover both the WLAN and UWB, operating at a frequency range of 2.4~11 GHz, within of which, return loss(S11) is less than-10 d B, the isolation is lower than-15 d B.4. A compact triple-band inverted-F antenna for WLAN and Wi MAX MIMO system is proposed. Its main radiation element is evolved from simple inverted-F antenna, works at 2.4 GHz, 3.5 GHz. The parasitic element works at 5.2 GHz, 5.8 GHz, In order to reduce the size of the antenna and improve the effect of the truncated ground plane on impedence match, a slot is added. A four-element array configuration of the proposed antenna for MIMO application is also studied. |
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