A Novel Dual-Band MIMO Antenna with Lower Correlation Coefficient

This paper demonstrates a novel dual-band operated MIMO antenna which consisted of planar monopole (main antenna) and 3D slot element (auxiliary antenna). The main antenna is printed on a 1.6 mm thick FR4 board, while the auxiliary antenna is fabricated with gold-coated copper. A lumped impedance network is applied to enhance matching effect at port1. From simulations by commercial software, it can be found that the proposed antenna is able to cover GSM800, GSM900 (lower band), and LTE/ WiMAX/WLAN (higher band) quite well. Good agreements between simulations and measurements are obtained. Corresponding measured results, antenna efficiency, peak gain, and radiation patterns, are presented at the same time. By equipping a passive decoupling element, the coupling power on the ground is radiated into free space, and great enhancement of isolation between antenna elements, especially for lower band, is achieved

A Sodium laser guide star coupling efficiency measurement method

Large telescope's adaptive optics (AO) system requires one or several bright artificial laser guide stars to improve its sky coverage. The recent advent of high power sodium laser is perfect for such application. However, besides the output power, other parameters of the laser also have significant impact on the brightness of the generated sodium laser guide star mostly in non-linear relationships. When tuning and optimizing these parameters it is necessary to tune based on a laser guide star generation performance metric. Although return photon flux is widely used, variability of atmosphere and sodium layer make it difficult to compare from site to site even within short time period for the same site. A new metric, coupling efficiency is adopted in our field tests. In this paper, we will introduce our method for measuring the coupling efficiency of a 20W class pulse sodium laser for AO application during field tests that were conducted during 2013-2015