Research On Antennas And Arrays Based On Novel Substrate Integrated Suspended Line

With the general progress of the wireless communication system and radar technology,the requirements of the antenna performance such as gain,frequency band and bandwidth are higher and higher.Researchers have proposed the antennas based on different structures,for instance waveguide antenna,microstrip antenna,substrate integrated waveguide(SIW)antenna,etc.Based on the substrate integrated suspended line(SISL)structure,which has the merits of low loss and self-packaged property,different kinds of SISL antennas and arrays are proposed and designed in this dissertation aiming at how to improve gain,expand bandwidth,increase the number of frequency band and miniaturize size and so on,which have been studied and analyzed.The main research contributions are listed as follows.High-gain SISL antennas are proposed.A novel self-packaged SISL quasi-Yagi antenna is designed,in which the suspended line to slot line transition is introduced to reduce the loss due to the coupling through air cavity.The bow-tie driven dipole is used to reduce the resonant frequency and widen bandwidth.Also,a compact SISL leaky-wave antenna with small size is designed.In order to excite the first higher order mode,asymmetric feeding is introduced.The tapered radiator is utilized to suppress back lobe and achieve impedance matching,and then the gain is improved.Wideband SISL antennas and arrays are proposed.Three kinds of antennas and arrays to expand bandwidth by increasing resonant frequencies with different principles are designed.Firstly,a 24 GHz cavity-backed slot antenna and array with slot coupling feeding for automotive radar is proposed.Two different resonant frequencies are generated through etching the bow-tie slot and rectangular ring slot on the element,and then the impedance bandwidth is expanded.The antenna array is composed of 16 antenna elements and differential feeding network.Next,a SISL stacked patch antenna and array for WLAN is designed.Via connecting the driven patch and feed line is utilized to produce a resonant frequency while a stacked patch with slant slot is introduced to generate another resonant frequency.The other resonant frequency is produced by the driven patch with U-shape slot and then the impedance bandwidth is broadened.The microstrip-slotline-suspended line transition is presented in the feeding network to achieve 180° phase difference and the antenna array is with 8 elements.Finally,a SISL circularly polarized stacked patch antenna and array is designed.Windmill slot etched on the driven patch is used to stimulate two orthogonal modes and two resonant frequencies are produced.Stacked patch and square ring strip are introduced to improve impedance matching and circularly polarized property.The sequentially rotated feeding network with microstrip-slotline-suspended line transition is proposed to feed the antenna array with 4 elements.Multiband SISL antennas are proposed.A dual band SISL antenna for WLAN is presented.Due to the multilayered structure,the dumbbell-shape strip added on the top substrate layer and rectangle slot etched on the ground plane are utilized to realize dual band without decreasing the antenna gain.To increase the number of frequency band,a triple-band multi-mode SISL stacked patch antenna is designed and the concept of step impedance resonator(SIR)is introduced in the antenna design.Two L-strips added on the top substrate layer are introduced to stimulate dual modes and two resonant frequencies are generated.The high frequency band is realized by using the driven patch with U-shape slot,and so the triple band of the antenna is achieved.In addition,a miniaturized high permittivity dielectric filled SISL antenna is proposed.The dielectric resonator antenna is based on five substrate layers with two air cavities,and the high permittivity dielectric is filled with the upper air cavity while the bottom air cavity is treated as a backed cavity which has significant effects on the resonant frequency.The relationship between the resonant frequency and the height of the backed air cavity is studied.In order to reduce the resonant frequency,a cross strip etched on the top substrate layer and attached to the high permittivity dielectric is introduced and then the resonant frequency is reduced.Moreover,the dielectric resonator antenna is self-packaged.