Analysis And Synthesis Of Conformal Antenna And Array

Conformal antennas have been widely used in modern radar systems with theirspecial advantages. First of all, because the antenna attaches with aircraft surface, itdoesn't affect the performance in aerodynamics. Then, with the same performance,conformal antennas can simplify the fixing, too. Plane phased antenna arrays have lotsof disadvantages such as narrow scanning angle and variable mutual couple related withthe scanning angle. However, the conformal antenna arrays such as circle array, spherearray, as a result of keeping the mutual couple balance, could avoid these defectsefficiently.This paper focus on analysis and synthesis of conformal microstrip antennas andarrays, and also make a further research in conformal microstrip antennas analysis,conformal microstrip antennas and arrays synthesis for solving the important, difficultyand front problems in present study. Several problems are studied systematic by thenumbers and deeply, and the contents list as follows.The first: accurate analysis of conformal microstrip antennas based on the volume,surface, wire integral equations (VSWIE).This section uses the VSWIE equation which takes four basis functions includingvolume, surface, wire and wire-surface junction, to analyze the radiation and impedanceof probe feed conformal microstrip antennas on arbitrarily-shaped, finite-sized groundplanes and substrates. The dielectric slab, conducting patch, ground plane, and the probefeed are replaced by equivalent volume current, surface current, wire current, andwire-surface junction singularity current respectively, with the four different basisfunctions. The method of moments (MOM) is used to establish the linear equationfunctions and the currents can be calculated by solving these functions. Then, theantenna radiation patterns and impedance characteristics can be computed easily.However, meshing the dielectric slab with volume makes unknows too huge to solveantenna arrays by MOM directly.The second: accurate analysis of conformal microstrip antenna arrays based on the VSWIE.As mentioned above, without accelerated algorithms, it's difficult to directlyanalyze the conformal microstrip antennas with MOM, which produces too muchunknown quantities by using volume meshing in substrate part. Hence, the multi-layerfast multi-pole algorithm (MLFMA) is used to accelerate computing and reduceconsuming of computer resources in this paper. Simultaneously, we combinephysics-optical (PO) in which the microstrip antennas is solved using VSWIE and metalplatform is solved using POThe third: design of conformal microstrip antennas.Because the conformal microstrip antennas can't be too thick, in this section, theresearches of conformal antennas are based on single layer substrate. For broaden theoperating band, a tool is introduced by combining the MOM and genetic algorithm (GA)for broadband microstrip antenna design, and two kinds of antennas are designed by thismethod. For overcoming the limitation of fixed space on the aircraft platform,reconfigurable technique has been researched in this paper: (1) novel frequencyreconfigurable microstrip antenna; (2) novel pattern reconfigurable microstrip antenna;(3) novel broadband pattern reconfigurable microstrip antenna; (4) novel circularpolarization reconfigurable microstrip antenna.The forth: application of space mapping(SM) technique in the optimization ofconformal antenna.Conformal antennas based on complex carrier are designed with SM. The examplesdemonstrate that SM can reduce the overall design process by an order of magnitude (10times). A plane structure antenna is treated as a coarse model, then, the same coarsemodel is used to optimize the conformal microstrip antennas in different carriers.Simultaneously, we find that the convergence of this scheme is sensitive to the responsefunctions in the same problem. So, different response functions are studied foraccelerating convergence in this paper too.The fifth: Synthesis of conformal antenna arraysSynthesis of antenna arrays is a multi-objective problem. In the simplesingle-objective algorithm, the different objectives with different weights are combinedinto a single cost function, and the optimization process must be repeated when an objective goal changes. Moreover, the desired objective goals can't be achieved unlessall the weights are exactly chosen. In this section, the improved NSGA-â…¡approach withthree modifications, is put forward to improve the diversity and convergence in theoptimization of antenna array.