Research Of Miniaturized Microwave Devices Based On Slot-Line

With the miniaturization of personal communication terminals,reducing the size of the circuit has become an important requirement for the design of wireless microwave devices at the front end.Researching and developing the miniaturization technology of the structure which directly integrated in the slot-line of the ground plane can make full use of the three-dimensional space of the circuit and satisfies the requirements of miniaturization and high performance of microwave devices.Around this subject,a variety of novel slot-line structures are presented in this paper,which explain the physical mechanism of the realization of miniaturization,and a variety of microwave devices with small size and high performance are realized by using this slot line.The main contents of this paper are shown as follows:1.The slot line in the application of signal interference filter is studied.A design of signal interference band rejection filter based on slot line structure is presented.Compared with the traditional microstrip structure filter,the slot line structure can achieve higher characteristic impedance under the condition of equal impedance ratio.To verify this conclusion,the signal band rejection filter with microstrip line structure and slot line structure are designed respectively.The simulation result of two kinds of structure filters demonstrates that the performance of the slot line structure filter has more advantages.2.The capacitive loading technology of closed slot structure is studied.Based on the establishment of equivalent transmission line model,the lumped circuit model is developed.Found in the study that the capacitive loading closed slot can significantly reduces the resonant frequency of the slot-line,at the same time,effectively improve the Q value of the slot-line.Based on these two characteristics,the solution of the selective lifting of band-stop filter and the size compression of slot antenna are obtained.Thus,a capacitive loaded U-slot defected ground structure(DGS)model is proposed which shows strong selectivity.At the same time,a capacitive slot antenna structure model is proposed,which can make antenna works at lower resonant frequency.3.The miniaturization technology of multilayer microstrip transition based on slot-line is studied.Through the use of opening slot line structure and based on the theory of the filter,a broadband integrated technique for the transition of the opening slot line is proposed.It can not only reduce the length of the slot line to half,but also realize the filtering of the multilayer microstrip transition and improve the comprehensive performance of the transition effectively.At the same time,the interleaved loaded opening slot line is proposed,which can further reduce the circuit size of the multi-layer transition.4.The cooperative design technique for the differential filter and differential antenna with multilayer structure is studied.The differential feed patch antenna is considered as the last-order resonator of the filter,a design method of differential filter antenna is proposed to achieve the filtering of the antenna response and the direct interconnection between the differential antenna and the back end of the differential circuit.