Design And Simulation Of Ka-band Laminar Ferrite Microstrip Circulator

Circulator belongs to microwave ferrite device,using to control the unidirectional transmission of microwave signals.With the development of science and technology,the shortcoming of bulk ferrite circulator's volume and weight make the film circulator research popular.Due to the current development of film technology,it is still difficult to fabricate a single-layer ferrite film with a certain thickness and excellent properties.The researchers found that the dielectric buffer layers are added have an important significance for improving the quality of the ferrite film.Therefore,this article based on multi-layers ferrite film making a circulator at 39 GHz.The main work of this article includes the following four points:(1)Collating the circulator related theories.(2)Proposed the multi-layers ferrite film structure circulator.The design confirmed that the best ferrite thin-film layer was double-layers,and then explored the central junction radius and other parameters.The results show that the optimum thickness of the ferrite flim is 20 ~ 25?m,the radius of magnetization is 1.3 times the center junction radius,the magnetization is 1100 KA / m,the coupling angle is 0.3rad,the wave port width of circulator is greater than 2 times the thickness of the transmission line,the height of wave port is between 6 and 10 times the thickness of the substrate.(3)The influence of the thickness and the relative dielectric constant of buffer layer on the device is investigated and then gets the best thickness.It is proved that the lower the relative dielectric constant of the buffer layer is,the better the effect to the device,and this phenomenon is analyzed.(4)The sample is made based on the simulation,the results show that the center frequency of the device shifts to the right by about 0.3GHz.The return loss and isolation basically meet the requirements of the circulator,but the disadvantage is that the insertion loss is large,indicating that the sample has a large transmission signal loss.The multi-layers film circulator designed in this article can reduce the difficulty of coating.At the same time,the simulation results show that there is also a certain increase in the ring effect.It will provide a reference for the future innovation of circulator structure.