刘芳焕 赵全明 张馨 薛绪掌 郑文刚 王英东

摘要 目前Sub-GHz频段的无线传感器在温室生产中得到广泛应用，了解射频信号在温室中的传输特性与分布情况已经成为当前研究热点。研究了以433 MHz为工作频率，通过调节发射节点与接受节点高度以及两者之间的水平距离，采用频谱仪获得接收信号功率（dBm），通过回归分析构建日光温室中的无线电波传播模型，并仿真得到信号在日光温室中的分布情况。研究表明：在发射天线的每个高度上，不同的接收天线高度层接收信号强度符合对数路径损耗模型，温室内的路径损耗指数（2.19）比室外（3.6）的小，温室内无作物接收信号强度比有作物大约10 dBm;温室北侧接收信号强度略高于南侧，高约5 dBm;温室中布置节点应避开有金属（铝线等）的位置。

关 键 词 日光温室;无线传感器;路径损耗;Sub-GHz无线射频;传输模型

中图分类号 TN925;S625.51     文献标志码 A

文章编号：1007-2373（2021）06-0038-07

Abstract At present， Sub-GHz band wireless sensor has been widely used in greenhouse.Understanding the transmission characteristics and distribution of radio frequency signals in greenhouse has become a hot research. In this paper， 433 MHz is used as the working frequency， and the received signal power （dBm） is obtained by the spectral instrument through adjusting the height and horizontal distance between the transmitting node and the receiving node， and the radio wave propagation model in the solar greenhouse is constructed by regression analysis， and the distribution of the signal is simulated.The study shows that the received signal strength of different receiving antenna height layers conforms to the logarithmic path loss model. The path loss index （2.19） in the greenhouse is smaller than that in the outdoor （3.6）. The received signal strength of no-crop in greenhouse is about 10 dBm， higher than that of crop in greenhouse; and on the north side of the greenhouse it is slightly higher than that on the south side， with a height of about 5 dBm. The arrangement of nodes in greenhouse should avoid the location of metal （aluminium wire， etc.）.

Key words solar greenhouse; wireless sensor; path loss; Sub-GHz radio frequency; transmission model

目前物联网在温室环境在线测控、水肥一体化、生产管理等方面得到了广泛应用[1-4]。采用433 MHz频段无线传感器网络具有低功耗、传输性能稳定等优点，在设施农业应用中占据很大的比重。由于日光温室环境复杂，建筑物材料不同、种植作物不同、电气参数不同均会对附带监测信息的电磁波造成干扰[5-7]，从而影响无线传感器网络信号传输与节点部署，因此需要采用无线传感器节点设备对日光温室中射频信号的传输特性与分布情况开展研究。

当前对农业环境下的无线电波的传输特性的研究主要集中在无建筑设施情况下以及在各种温室环境中的传输特性研究。……