This paper expatiates on the definition and solution of antenna phase center in planar near field. It provides the method of error analysis modeling and the 18 error items of phase pattern. And the final boundary of the error is obtained by error synthesis method. Based on error matrix, Monte Carlo method is employed for error analysis of phase center.
In this paper, a novel UWB (Ultra-wide Band) antenna is proposed. This design mainly consists of a wide slot square ground plane and a frequency independent feed line-a 0.5 turn equiangular spiral, which are etched on each side of a substrate separately. Additionally, a circular patch connected with the slotted ground is introduced to tune the working bandwidth of this antenna. Prototypes are instructed and tested to know the performance of the proposal. From the results, it can be seen that the proposed antenna has enough impedance bandwidth for UWB applications with VSWR (Voltage Standing Wave Ratio) less than 2, acceptable radiation patterns, as well as relatively high gains.
Objective To investigate the osteogenic ability of human allogenous acellular bone(HAB) loaded with bone marrow stromal cells (BMSCs) . Methods Human acellular bone was obtained from the iliac bone of fresh corpse, processed with 15% hydroperoxide and ether solution and sterilized for conservation. BMSCs from living femoral shaft bone marrow were cultured immediately in ordinary and mineralized medium composed of DMEM, fetal bovine serum, dexomethasone, β-glycerophophate and ascorbic acid. After BMSCs confirmed rapidly proliferated and differentiated toward osteoblast, which was proved by alkaline phosphatase(ALP) and osteocalcin (OCN) detect in the culture medium, they were concentrated and implanted within HAB scaffold. After this composite was soaked and cultured for another 8 days, ALP and OCN in the medium were then assayed again. The his-tologic presentation was determined under light microscope and scanning electron microscope. Results HAB was well prepared showing a complete reservation of its porous structure. ALP and OCN activities in the induced culture medium were significantly higher than in the ordinary medium( P 0.05) . The composite bone loaded with BMSCs demonstrated a positive presentation of the osteogenic function by the biochemical assay. BMSCs were adhered and grew well in HAB scaffold. Conclusion HAB loaded with induced BMSCs has an excellent osteogenic function in vitro and presents an effective potential to be a good bone tissue engineering material.
A novel planar monopole antenna for multiband operation is presented. The proposed antenna consists of an E-shaped patch and a 50 Ω coplanar waveguide (CPW) transmission line. There are two L-shaped slots cut out of the ground and one U-shaped slot out of the E-shaped patch. By etching the slots, band-rejected filtering properties in the PCS/WiMax bands are achieved. Analysis of the current distribution on the antenna reveals that the addition of the slots creates two stop bands, which is responsible for the multiband properties. This technique is suitable for creating ultra-wideband((UWB) antenna with narrow frequency notches or for creating multiband antennas. This paper presents the design and experimental results of the proposed antenna. Moreover, the study also investigates the tuning effects of the geometry parameters on impedance matching.
The classic method of testing array antenna is measuring the beam pattern separately, which suffers from low efficiency. In this study, a fast measurement method used for received array antenna has been present. Firstly, the patterns of element antennas have been tested using multi-channel receiver. Then the entire pattern could be computed by weighting the information of elements. The information contains amplitude and phase, which could be obtained by theory or measurement.
This paper introduces a multi-probe planar near field for antenna measurement. The system consists of robot arm, probe array, vector network analyzer and real-time controller. It deals with the data acquisition and analysis of DUT, also raises the multi-probe calibration method for the system.
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