Research And Application Of Spatial Filtering Antenna Design Method

Spatial filtering antenna is a type of antenna technology that implements interference suppression and signal enhancement by filtering signals in the spatial domain.It has received increasing attention in fields such as medical equipment,satellite communication,obstacle detection,meteorological radar,radio astronomy,and airborne collision avoidance systems.The radiation pattern of the spatial filtering antenna is usually a fan-shaped pattern composed of a main lobe and two side lobes.The main lobe is typically located in the center of the fan-shaped pattern,providing strong and stable signal coverage and transmission,while the side lobes provide weaker signal coverage and transmission.Therefore,it can minimize signal energy waste,improve wireless link performance,and reduce signal interference from sources outside the intended area.Currently,there are three main methods to achieve fan-shaped beam,which are the metamaterial surface lens,antenna array,and shaped dielectric lens.However,these methods have high complexity,require large power consumption,occupy large space,and have poor flexibility.To address these technical issues above,this thesis proposes two design methods for spatial filtering antenna units and presents a use case scenario.The main work of this thesis includes three parts:1.A sector beam antenna unit based on planar Yagi antenna structure is designed.The main body of the antenna unit consists of two plane Yagi antennas with opposite tilt angles.By shifting and rotating the phase lines,the two plane Yagi antenna modules radiate in two different directions respectively.By simultaneously feeding the two sub-antenna modules,the directional pattern is synthesized into a sector beam.2.An antenna is designed that can achieve sector beam effect through a single feeding port,solving the disadvantage of the previous design that required a power splitter for feeding,and further reducing the cost.This design uses a simple dipole antenna to stack different directional directing units to produce two directional beams.By adding the beams together,the same effect of the sector beam is achieved.By controlling the number of directing elements and the distance between them,the width and gain of the sub-radiation beam can be controlled.Thereby controlling the width of the integrated fan beam and the antenna gain.3.Based on the conclusion drawn from the results of the second design,an intelligent warehousing system was selected as the practical application scenario,and a circularly polarized spatial filtering antenna used in the Radio Frequency Identification(RFID)field was designed.The antenna is suspended above the shelf and uses the metal shelf as the ground plane,which not only solves the electromagnetic interference caused by the metal shelf on the antenna,but also simplifies the antenna structure.By scanning the goods below in a directional manner,the phenomenon of misreading adjacent items is greatly reduced.Moreover,the reading area can be controlled by adding directional units,making the application scenario more flexible.