The Research Of Antennas And Antennas Arrays Based On SISL Platform

Antenna plays an important role in modern communication systems which is treated as the eye of the whole system and its performances effect the properties of the proposed system.Generally speaking,the feeding structure of the antenna can be chosen as microstrip line,coaxial wire,coplanar waveguide and substrate integrated waveguide(SIW).Microstrip line is a common transmission line and possesses merits of low cost,simple structure and easy fabrication.While at millimeter wave band or higher frequency band,the dielectric and radiation loss of the microstrip line become larger which may deteriorate the performances of antenna and lead to a lower efficiency.Substrate integrated waveguide is another kind of wave guiding structure.Compared with conventional metallic waveguide,it has advantages of light weight,easy fabrication and low cost.For better performances,the fundamental mode of SIW is usually stimulated to feed the antenna.To get better antenna's performance,lower loss and present more feeding structures of antenna,a new kind of transmission line named by substrate integrated suspended line(SISL)is introduced in this paper.And many works have been done based on SISL platform.SISL is a self-packaged transmission line which is a multi-substrate layers' structure and is composed by 5 layers of substrates.Compared with the conventional suspended line with metal housing,the SISL possesses merits of light weight,easy mechanical process and low cost.In this paper,many kinds of antennas have been proposed based on the SISL platform such as dual band antenna,dielectric resonator antenna,cavity-backed dipole antenna and its arrays.Many dual band antennas are a single layer structure and the feedline together with the radiator are printed on both sides of the substrate respectively.It is known that the SISL is a multi-substrate layers' structure and more metal layers can be utilized which presents more flexibility for the design of the multi-band antennas.Based on the SISL structure,the dielectric resonator antenna can be designed by introducing the substrate ring to fix the dielectric resonator.The metalized holes can be designed in the ring to feed the dielectric resonator.A cavity-backed dipole antenna is also discussed based on the SISL platform.As for the conventional cavity-backed antenna,the cavity structure is realized by utilizing metallic structure which may lead to high cost and heavy weight.Many cavity-backed antennas is fed by microstrip line with a transition from microstrip line to parallel strip line while the substrate loss and radiation loss may lead to a lower efficiency especially for arrays.To solve the problems above,a novel SISL based cavity-backed dipole antenna array is designed.The proposed array is fed by double side substrate integrated suspended line(DSISL)and the dielectric loss is reduced largely.The radiation loss of the SISL is very small and it is a self-packaged structure thus lead to a better front-to-back ratio.What's more,the cavity structure in this design is a multisubstrate layers' structure other than the metallic structure which can be fabricated more easily.The proposed four elements cavity-backed antenna array has measured 10 dB impedance bandwidth of 19.7%,i.e.,from 22.77 to 27.75 GHz.At 25.45 GHz,the measured gain is 14.3 dBi and the measured radiation efficiency is 91.2%.Side lobes of better than-15 dB and front-to-back ratio of better than 27 dB are all obtained at the same frequency.