Research On The Synthesis Of Antenna Array Using Element-Level Pattern Diversity Technique And The Synthesis Of Conical Beam Antenna

Radiation pattern is one of the most important parameters in antenna design,and antenna synthesis is one of the key problems in antenna community.Based on the research of predecessors,this dissertation providing a new concept of synthesis called element-level pattern diversity(ELPD)technique.Different to conventional array factor synthesis,the ELPD synthesis provides another degree of freedom,which will bring many opportunities to antenna community.In addition,the synthesis of conical beam antenna which is widely used in milltary and communication system is investigated.The main work can be summarized as follow:(1)Summarized and providing a new synthesis technique called ELPD technique.The radiation pattern of each element is different in ELPD array.The synthesized pattern is obtained by the superposition of different radiation patterns as well as the wave path difference,thus introducing a new degree of freedom.The Fourier transform is introduced to ELPD array synthesis,and the physical meaning is given.The excitation coefficients are obtained by artificial bee colony(ABC)algorithm in practical design.Three examples of broadside beam patterns and end-fire beam pattern are given.A tolerance analysis of the ELPD array is presented.The discussions regarding its advantages and limitations show that,in some cases,the ELPD suitable to synthesize broadside far-field beam patterns with rapidly changing current distributions on the antenna,for example,flat-top beam and dual beam.The ELPD array can achieve a similar performance with fewer elements compared with the conventional array,resulting in a simple feed network.Besides,compared with the synthesis of a conventional array,for the same amplitude error or phase error,the pattern deviation is less obvious.(2)A dual beam ELPD array is presented to satisfy the requirement of flexibility in controlling the beam-pointing angle and gain.The rectangular patch is excited by two SIW slots.The length of the patches are different,thus different modes are excited.Different radiation patterns are obtained because of different modes.A 3-element array was designed and fabricated to verify the theory.The 11%impedance bandwidth at a center frequency of 5.8 GHz with a-10 dB return loss and the measured maximum gain of 10.1 dBi at the beam-pointing angle of ±49°are achieved.(3)A magneto-electric(ME)dipole ELPD array is presented to satisfy the requirement of high gain as well as equal E-and H-plane radiation patterns.The E-plane radiation pattern is obtained by the superposition of the radiation patterns of different electric dipole modes,while the H-plane radiation pattern is obtained mainly by the array factor of the magnetic dipoles.This linear array can achieve similar performance with conventional two-dimensional array,a 3-elements array is designed as an example to show the validation of the theory.The measured 12,5%impedance bandwidth at a center frequency of 2.4GHz with|S11|<-10dB and stable radiation patterns is achieved.(4)An ELPD array using concentric loop configuration is presented to satisfy the requirement of high gain conical beam with specific beam-pointing angle.The concentric loop configuration can be divided into concentric current loop and concentric magnetic loop.Numerical results are given to prove the validation of concentric current loop.The magnetic loop array is achieved by using nested horn configuration.A 3-element array is designed to verify the theory.The measured maximum gain at the beam-pointing angle of 18°is 11.9 dBi.The 6%impedance bandwidth at a center frequency of 10 GHz with |S11|<-10 dB and stable radiation patterns are achieved.(5)The combinations of ELPD array with conformal array and time-modulated array are presented.Numerical results show the validation of the concept.The advantages such as saving array elements are still available in the combined array.(6)A dual conical beam periodic dielectric rod leaky wave antenna is presented.The dual conical beam is achieved by adjusting the length of the periodic structure.A dual conical beam is designed and simulated.Simulation results show that the two beam-pointing angles are117.5°and 123.2° with related gains of 11.3dBi and 11.18dBi,respectively.(7)A CPW-fed printed conical beam array is presented to satisfy the requirement of high gain and large beam-pointing angle.This array can achieve omnidirectional pattern while maintaining planar structure because of the employment of CPW.Taylor distribution is used to suppress the side lobe level.The beam-pointing angle can be precisely controlled because of the modification of the phase error.The design procedures are proposed and a 16-element array with beam-pointing angle of 77°is fabricated and measured to verify the design.The measured 15 dB return loss bandwidth is 11.4%at central frequency of 10.5 GHz.The measured gain and the side lobe level are 10.3 dBi and-20 dB,respectively.