Research On Large Band Gap And Characteristics Of Microstrip Antenna Based On Microwave Photonic Crystal

The photonic crystal is new periodic structure composed of two or moresubstrate of different dielectric constant. This concept was first proposed by S.Johnand E. Yablonovitch in1987. The most important characteristics of photonic crystalare Photonic band gap (Referred to as PBG). Its size is small, so processing andmanufacturing are not easy in the optics field. But when it is applied in microwaveregion (300MHz~300GHz), microwave photonic crystal has been developed rapidly.In this paper, firstly, the characteristics of photonic band gap have been analyzed.The models of microwave photonic crystals of substrate column and air hole are builtusing the software of BandSolve. A large number of simulation calculations are madethrough plane wave method. The structure of commonly used square lattice photoniccrystal has been optimized, and a new photonic crystal of embedded structure isdesigned, which can improve the band gap of square lattice. The new photonic crystalof embedded structure has been studied and designed, which has been embedded inthe gaps of square lattice with the same kind of square lattice, the concrete structure inthe third paragraph is introduced in detail.Secondly, to contrast the size of band gap that both the substrate column and airhole types photonic crystals of embedded structure with square lattice, a large numberof simulation test are done. For photonic crystals of substrate column, the resultsshow that if the cross section is round, square or hexagon, the TE、TM and completeband gap of photonic crystals of embedded structure are bigger than square lattice’s.And for air hole types photonic crystals, the results of TE、TM and complete band gapare same with substrate column type photonic crystals for round and hexagon crosssection. Then we will compare the embedded structure’s complete band gap withtriangular lattice, the data show that the embedded structure is bigger than triangularlattice’s in most instances.At last, the characteristics of microstrip antenna based on microwave photonic crystal have been analyzed. The new structure photonic crystal is applied to dual-bandmicrostrip antenna. The data show that the return loss decreased30.6617dB, theantenna pattern has been improved, front lobe radiation increases about2dB and backlobe radiation decreases about15dB at most, the antenna has better impedancecharacteristics and radiation efficiency. The new structure microstrip antenna withphotonic crystal reaches the aim to improve the performance of the antenna, and theresult is better than square lattice、triangular lattice applied to the same antenna. And itcan effectively suppress the surface-wave of microstrip antenna, thereby improvingthe gain and direction pattern.