Search

A multiple-input–multiple-output (MIMO) antenna with high frequency selectivity and controllable bandwidth, is proposed for band-notched ultrawideband (UWB) applications. In other words, it has a bandstop-filter-like response (second-order notched band) at the aimed rejected band. It consists of two rectangular printed monopole (PM) elements and a simple stepped ground stub to enhance wideband isolation. For achieving the second-order rejected band of the IEEE 802.11 wireless local area network (WLAN) band from 5.15 to 5.85 GHz centered at 5.5 GHz, two parasitic modified split-ring resonators (PMSRRs) and two inverted L-shaped branches (ILBs), are utilized. Measured results prove a bandwidth of S11

This paper presents a compact multiple-input-multiple-output (MIMO) antenna for wireless portable device applications. It entirely covers the Bluetooth (2.4–2.484 GHz), Worldwide Interoperability for Microwave Access (WiMAX) (3.4–3.69 GHz), Wireless Local Area Network (WLAN) (5.15–5.825 GHz), and ultra-wideband (UWB) (3.1–10.6 GHz) operating bands. This antenna consists of two planar polygon printed monopole(PM) antennas, a rectangular slot and a triangular trim on the antenna element to lower down the low-cutoff frequency for improving the impedance matching, and a stepped ground stub to improve the isolation. Two rounded corners are simultaneously used on the ground for the impedance matching at medium-high frequency. The results of simulation and measurement prove that the −10 dB bandwidth of this antenna is from 2.4 to 11 GHz, and the isolation is less than −15 dB in the entire band, which can satisfy the actual requirements according to most literatures. The envelope correlation coefficient is less than 0.02. The size of this antenna array is 40 × 36 mm2. © 2016 Wiley Periodicals, Inc. Microwave Opt Technol Lett 58:783–787, 2016

In this paper, a very compact ultra-wideband (UWB) multiple-input-multiple-output (MIMO) antenna, with a high isolation and triple notched bands, is proposed. Its size is dramatically decreased to 30× 26× 0.8mm3 on a cost-effective FR4 substrate. It consists of two rectangular printed monopole (PM) elements and a simple stepped ground stub to enhance wideband isolation. For two different rejected bands of the wireless local area network (WLANs) covering 5.15–5.35 and 5.725– 5.825GHz, four parasitic C-shaped split-ring resonators (PCSRR) are placed on either side of the feed line. By etching two inverted U-shaped slots on the center of the patch, the notched frequency at 4GHz C-band (3.7–4.2 GHz) of satellite communication systems is obtained. The results of simulation and measurement prove a bandwidth of S11 < −10 dB and S12 < −21 dB over the whole band (3.1– 11.2GHz) excluding the three independently adjustable rejection bands. Hence, the proposed UWB MIMO antenna has a very small size, simple structure, higher isolation and three narrower notched bands which effectively save more useful frequencies. Moreover, it is a good candidate for wireless portable UWB MIMO applications.

A novel eight-band handset antenna with 10 × 60mm2 is proposed in this article which covers LTE700/2300/2500 and GSM850/900/1800/1900/UMTS2100. The developed antenna consists of six branches, and a notch is cut from the printed circuit board. The folded stripe has been adopted in the structure, which improves the performs of the antenna notably. The process of the design work has been presented step by step. A prototype of the proposed antenna is fabricated. The tested results including efficiency, and gain.

In this paper, a compact dual-resonator loaded ultra-wideband (UWB) multiple-input-multiple-output (MIMO) antenna, which has a bandstop-filter-like response (second-order rejection band) with high frequency selectivity and controllable bandwidth at the aimed notched band, is proposed. The MIMO antenna consists of two rectangular printed monopole (PM) elements and a simple stepped ground stub to enhance wideband isolation. Compared with the traditional first-order band-rejected UWB MIMO antenna, the selectivity and bandwidth-controllability of the rejected band is greatly improved and its size is dramatically decreased to 32×26×0.8mm3 on a cost-effective FR4 substrate. The results of simulation and measurement prove a bandwidth of S 11 12 < −15 dB at 3 GHz–12 GHz excluding the rejection band of 5 GHz–5.95 GHz. Hence, it is a good candidate for wireless portable UWB MIMO applications.

This paper presents a small-size multiple-input-multiple-output (MIMO) antenna for wireless portable device applications. It entirely covers the Bluetooth (2.4–2.484 GHz), Worldwide Interoperability for Microwave Access (WiMAX) (3.4–3.69 GHz), Wireless Local Area Network (WLAN) (5.15–5.825 GHz) and ultra-wideband (UWB) (3.1–10.6 GHz) operating bands. This antenna consists of two planar polygon printed monopole (PM) antennas, a rectangular slot and a triangular trim on the antenna element to lower down the low-cutoff frequency for improving the impedance matching, and a stepped ground stub to improve the isolation. Two rounded corners are simultaneously used on the ground for the impedance matching at medium-high frequency. Simulated and measured results prove that the −10dB bandwidth of this antenna is from 2.4 to 11 GHz, and the isolation is less than −15dB in the entire band. Its size is only 40×36 mm2 on a cost-effective FR4 substrate.

A planar triple-band antenna with size 40 × 18×0.8 mm3 for LTE/GSM/UMTS and WLAN/ WIMAX is developed in this paper. The antenna is constructed in four steps. The first step is named Antl. In one side of the substrate, a non-folded strip is connected with a ground plane and a rectangle patch at both end of the non-folded strip, respectively. Antl is fed by a T-strip, which is in the other side of the substrate. Ant1 generates two modes at 2.8GHz and 1.97GHz and is responsible for the operation band 1.25–3.65GHz. The second step is named Ant2. On the basis of Antl, the non-folded strip is changed into folded strip. Two new resonant modes at 680MHz and 5.8GHz are introduced. Ant2 is responsible for the operation band (660–1120MH), (1.71–3.85 GHz). The third step is named Ant3. On the basis of Ant2, two branches (Br-1, Br-2) are introduced. Br-1 and Br-2 are in the same side of Ant1 and connected with the ground plane. Then the operation band (5.15–6.17 GHz) is added on the basis of Ant3. The fourth step is named Ant4. A slot is etched from the rectangular patch, and the impedance is greatly improved in the three operation bands. As a result, a triple-band antenna covering the LTE700/ 2300/ 2500 (1710–2690 MHz)/GSM850/900/ (690–960MHz) /GSM1800 / 1900 / UMTS (1710–2170 MHz) / WiMAX3.5 GHz (3400 ∼3650MHz) /5.4GHz (5250∼5850MHz) is formed. The gain for the proposed antenna is 1.2–4.2dBi, and the radiation efficiency is about 67%–95%.

From the angle of knowledge, the firm essentially is knowledge aggregate, at the same time the firm is also a vital organism with the biological similarity. For this, the article inquired into the enterprise knowledge innovation related questions according to the evolution biology related concept and theory from the new angle of view with analogism method. Firstly, the article established concept systems of the firm bioengineering based on the knowledge. Then studied the enterprise exclusive knowledge (enterprise gene team) innovation mechanism and process, in which the article has emphatically constructed and explained the enterprise exclusive knowledge continual innovation diagram.

Based on the numeric attributes of 114 typical nature reserves in China, a new category system was established by using cluster analysis method. Compared with the China national category system of nature reserves, the new category system was simpler and more applicable. The 4 categories in the new system matched well to the categories I , II , IV, and V in IUCN category system, respectively. The new category system, characterized by the consistency of category criteria and scale, could avoid the deviation caused by subjective category to some degree, and provide a quantitative standard for the classification of nature reserves in China.