Research On Key Technologies Of Front-end Circuits Based On Sisl Platform

Radio technology has become one of the core technologies in the modern information society.It has important and wide applications in many military and commercial fields such as wireless communication,satellite navigation,radar,and radio astronomy.As the key component of the radio technology,the RF/microwave/millimeter wave transceiver front-end is the hardware support in the radio industry.With the development of modern radio technology,higher requirements have been put forward for front-end circuits in terms of low loss,miniaturization,low cost,high integration,and high performance.Based on substrate integrated suspended line(SISL)platform with multi-layer structure,this dissertation will conduct the key technology research on various of front-end circuits in terms of high performance,miniaturization,low loss,low cost,high integration,and self-packaging.The main contributions of this dissertation are summarized as follows:1.A compensation method to improve the directivity of the coupler is proposed.The directionality is improved by adding open stubs along the coupled lines,and in the meantime,the cascaded topology and defected ground structure is applied to ensure the high coupling coefficient.Based on SISL platform,two high directivity couplers and a high-performance Butler matrix are implemented,and they have advantages of low loss,self-packaging,and high integration.2.A meander-line type slow wave transmission line is proposed based on the self-packaged SISL platform.The gap of between the adjacent meander lines is reduced to form the edge coupling effect,and thus the slow wave factor can be improved.Plated through holes are used to interconnect the two metal layers to reduce the conductor loss.Two types of slow wave couplers are designed,and they have advantages of compact size,design simplicity,and self-packaging.3.The design and implementation method of SISL lumped circuits is proposed.All the used capacitors and inductors are implemented on SISL platform,and no soldering is required,which leads to low cost and low loss.A SISL second-order lumped coupler is designed and its bandwidth can be improved by adjusting the value of the lumped elements.A high-density interdigital capacitor based on the double-layer compensation concept is proposed,which helps to further reduce the circuit size.Based on the compensated capacitor,a SISL lumped balun is designed,which has advantages of small size and wide bandwidth.For the first time,a transformer based differential coupler is proposed,which can suppress the common mode and cross mode signal simultaneously.Implemented on the SISL platform,it has advantages of small size and wide frequency bandwidth as compared to the reported work.4.By packaging the defected ground structure and the slot line circuit insides the multi-layer SISL structure with EM shielding property,the radiation loss can be reduced,and it can also be self-packaged.A SISL wideband branch line coupler with stop-band property and a wide-band low-loss SISL magic T are designed,both of which have good performance as compared to the state of art.5.SISL patch based couplers with very low loss are proposed.By using double metal layers,patterned substrate,and EM shielding property,the conductor loss,dielectric loss,and radiation loss can be reduced.As compared to the state of art,the implemented SISL patch couplers show good properties in terms of low loss and self-packaging.For the first time,a low loss SISL Butler matrix based on patch element and honeycomb concept is proposed.Every component is assigned with an individual cavity,and via holes are designed between the adjacent cavities to form the via fence,which makes these components isolated from each other,and the system design will be more flexible and efficient.The proposed SISL Butler matrix operate at the 24 GHz band,and it is also integrated with an SISL antenna array on the common SISL platform,which shows very high integration.For the first time,a low-loss SISL phase shifter in the patch form is proposed.The phase shifting branch and the reference line are both designed by using triangular patches.Double-layer metal and patterned substrate are used based on the EM shielding SISL structure,and very low loss is achieved.The designed SISL patch-based phase shifter operates at the 24 GHz band.Using the 90° phase shifter,a SISL single balanced mixer is proposed,and it has low conversion loss and high integration.6.For the first time,a new SISL structure with multiple inner boards is proposed.For the broadside coupling circuits,the coupled lines are designed on different inner boards with middle supporting board to separate them.By cutting out the undesired substrate in the inner board,and hollowing the support board between the two inner boards,there is almost electric field distributed in the lossy substrate,which contributes to very loss dielectric loss.Two high directivity SISL coupled line couplers with double inner board,and a wide-band asymmetric Marchand balun based on the triple inner board SISL,are realized,and they have advantages of low loss and low cost as compared to the state of art.