Optimization And Calibration Of An Active Phased Array Antenna For Radar Communications

Mobile satellite communication terminals are fast growing in commercial market for maritime,aeronautical,and land-mobile applications.Recently,the demand for small antennas for wireless communication increased creating extensive research development on microstrip patch antenna design among microwave and Radio Frequency(RF)engineers to improve gain,high-data-rate communications,and compensate for propagation loss,side lobe loss,grating lobes and blockages on some array elements.As a result,there is significant increase in the demand for lightweight,low cost,ease of fabrication,low profile and steerable antennas,capable of tracking the satellite and applicable for wireless and radar communication systems.As a result of the challenges experienced in EM-driven designs,various methods have been developed to reduce high costs in improving the efficiency of conventional numerical optimization techniques into a cheaper and faster representation of the expensive computational model.Furthermore,calibration of an active phased array system suffers from temperature variation,phase shifters,a large number of elements in an array,mutual coupling and power dividers.In order to achieve a high gain active phased array antenna at a specific direction,accurate control of the phase,amplitude and radiation pattern of each of the elements is very important while summing up the power measurement of the signals along the beam's direction.In this dissertation,a cavity model is applied as the coarse model applying "response residual space" mapping(RRSM)techniques in optimizing a rectangular patch antenna design using MATLAB.More also,an improved calibration and optimization technique in an active phased array system steers antenna beam to the desired direction.The proposed methodology,and corresponding results of this dissertation are listed as follows:1)A cavity model is deployed as the coarse model in applying "response residual space" mapping(RRSM)techniques in optimizing a rectangular patch antenna design using MATLAB 2019b.This approach fine-tunes the input impedence matching surrogate by exploiting the RRSM.The EM simulator used for the fine model design is the commercial CST Studio Suite 3D EM simulation software.The SM technique aligns the coarse model with the fine model in an iterative optimization analysis.RRSM optimization techniques provide a progressive improved antenna design after each iteration based on the theoretical formulation and simple implementation strategy.These techniques are suitable for electromagnetic(EM)optimization problems with an extensive computational time required to achieve accurate solutions for antenna design.2)An octagonal(8)sequencing calibration algorithm is proposed for single and multiple kth antenna elements signal for the amplitude and phase measurement.The power measurement of the antenna element is excited in eight octagonal states with maximum likelihood algorithm.The overall effect of amplitude and phase error in an active phased array antenna using octagonal phase settings as the simultaneous calibration technique to achieve an efficient antenna array system uses linear equation.This algorithm considers a series of successive phase shifts varied on each element.At each phase shifts,the complex array signal variation is measured at the receiving mode of the active phased array antenna considering the power amplifier output for each antenna element.There are various challenges experienced which complicate the calibration algorithm such as,large numbers of elements,mutual coupling of radio frequency paths,temperature and driving power of power amplifiers.To overcome these challenges,a robust and consistent algorithm is developed using octagonal phase settings for single and multiple kth elements for faster direct calibration of an active phased array system.This efficient octagonal phase setting calibration algorithm is applicable for phased array antennas,satellites,wireless and radar communication systems.3)Euler's numerical method is proposed to simultaneously measure and calibrate the array element's electric field and array factor.This simple calibration algorithm is implemented for an active phased antenna array measurement of the amplitude and phase of all the antenna elements in the array system.Each element's phase shifts are periodically varied with a reference state through a feedback to the amplitude and phase calibration units and their variations were calculated and analyzed for the signal calibration.The method is theoretically studied using numerical simulations providing accurate performance and a very low tolerance to errors.This approach provides a multiple element far field calibration technique applicable for radar,satellite and wireless communication.4)An experimental study of the far field 2 x 2 active phased array antenna(APAA)validating the effectiveness and efficiency of the combination of 2D DFT and l1 compressive sensing approach is carried out for the antenna array calibration.The signal measurements of the four(4)elements in the array are evaluated at a state 0 where no errors exist in the system.The main contribution of this work is to formulate problem from phase shifter errors on the array.The accuracy,complexity,and hardware requirements of this method is determined by the 6-bits phase shifters attached to each antenna elements as the phase settings are evaluated during the measurement procedure and the phase settings are determined by the 2D DFT signal data processing and the h norm minimization compressive sensing(CS)algorithm for adequate calibration.It is important to emphasize that this analysis is applicable for radar communications.