Research On Focused Antenna With Tunable Focal Length

Technological development is driving the industry forward,and application requirements place higher demands on technology.With the continuous development of 5G mobile communication technology and the advent of the information age,intelligence and high energy efficiency have become the main trends in the development of the RF antenna field and even all walks of life.Therefore,focusing antennas with high energy efficiency naturally attract people's great attention.A focused antenna is an antenna that gathers energy in a desired area,can use limited energy most efficiently,and has a wide range of application prospects.Most of the research on existing focusing antennas is designed for a single scene,and does not meet the needs of intelligent development.Therefore,focusing antennas that can change the focal length and apply to more scenes are needed.Therefore,research on focusing antennas with variable focusing distance is very necessary.This article has conducted in-depth research on application requirements,focusing distance switchable focus antenna and continuous zoom focus antenna.The main work and innovations of this article include the following aspects:1)Propose a method to accurately design the amplitude and phase of the focused antenna array element using the time inversion method.This method uses the reciprocity theorem to take into account the coupling effect of the array element in the design process of the focusing antenna and the actual external interference,so as to obtain the most accurate amplitude and phase information of the array element under focusing conditions,and then design a focusing antenna with excellent performance.Focused antennas with focal lengths of 100 mm,150mm,and 200 mm at a center frequency of 5GHz were designed using a new method,and the antennas designed by the traditional method were compared.The results show that the performance of the focus antenna designed by the new method has been improved in all aspects,of which 100 mm The focusing accuracy of the focusing antenna is increased by 10%,and the gain is increased by nearly 3d B.2)A slot-coupled focusing antenna designed for a dual feed port operating at 5 GHz is designed.A feeding network with different phase compensation is used to feed the focusing antenna,and the focal length of the antenna is changed by switching the feeding port,so that the beam is focused at different positions.The simulation results show that the antenna can realize the transformation of energy peak position from 91 mm to 121 mm.3)A ring-shaped microstrip array focusing antenna designed to work at 5GHz can be designed to achieve a continuous and controllable change of the focal length in the entire focusing domain.In the design,a power divider is used to cascade the feed networks of the loops,and a lower-cost varactor diode is used to design a ring-coupled reflective phase shifter to achieve a phase shift change of more than 360 ° under low loss,and further Integrated into the feeder of the inner loop,the phase difference between the two loops is realized by controlling the bias voltage of the phase shifter,and finally the continuously controllable zoom of the entire focusing domain of the antenna is realized.The simulation results show that with the change of the electric control capacitance,the focusing position of the focusing antenna can achieve continuous changes in the expected area.