Research On Millimeter Wave Optical Control Antenna

As radar has been playing an increasing important role in electronic information warfare,the core component of it: the phased array,has also been raised with higher and higher indicators.In order to meet the requirements of modern warfare for radar performance.In recent years,many domestic and foreign scholars have devoted themselves to designing and implementing phased array antennas with excellent performance under conditions such as millimeter wave and even terahertz frequency bands,ultra-wideband,and large aperture.But they are often affected by limited to the aperture effect of the array,the large attenuation in the high frequency band and the extremely high cost and other factors.Based on the concept of photoelectric effect of semiconductors.Using light directly to control millimeter waves to achieve scanning is a new idea to solve the above contradiction.This method requires almost only a light source,suitable semiconductor materials,and millimeter wave sources.So it is reducing complexity.At the same time,it will not introduce interference and spurious signals due to various active chips and transceiver components.The main research object of this paper is the millimeter-wave light-controlled scanning antenna based on Fresnel half-wave plate.It uses light of a certain power and a specific irradiation scheme to excite a certain concentration of carriers at the corresponding position of the silicon wafer to change its transmission characteristics to millimeter waves.When the distribution of carriers happens to make the silicon wafer like a Fresnel half-wave plate,the incident spherical millimeter wave is diffracted into a plane wave with a certain angle.Thereby achieving beam forming.Further changes to the corresponding irradiation scheme will complete the beam scanning.Although,in recent years,domestic and foreign scholars have conducted extensive research on the scanning antenna of this structure,there are still some problems to be solved:1)There is no perfect theoretical model for this type of antenna;2)The performance change when extending its working frequency band to millimeter wave is not very clear;3)Current research focuses on transmissive structures,for reflective structures less;4)The currently achieved antenna efficiency differs greatly from the theoretical value.Therefore,on the basis of previous work,this paper attempts to obtain a clearer understanding of the millimeter-wave light-controlled scanning antenna based on the Fresnel half-wave plate.The main contributions are as follows:1)First,combining the relevant knowledge of semiconductors and optics,detailed analysis and mathematical derivation of the properties of photo-generated plasma and its impact on the electromagnetic wave transmission characteristics,and also predicted its performance changes in the millimeter wave band(this paper working frequency 220GHz)trend.2)In order to improve the efficiency of the antenna,feed horns for transmissive and reflective scanning antennas were designed and corresponding performance simulations were carried out.The simulation results reached expectations.At the same time,a horn bias feed scheme was designed for the transmissive structure,and two feed systems were designed for the reflective structure to eliminate the signal source's blocking of the reflected beam.3)At the same time of completing the physical processing,a proposal was made to use a projector and a near-infrared laser as light sources,and a preliminary experiment was completed using the projector.The experimental results show that light can successfully control the millimeter wave transmittance in the silicon wafer.4)By processing different Fresnel annulus on the PCB and carrying out actual measurement,the antenna has the capability of beam forming and beam scanning successfully.