Design Of Compact Filtering Antenna And Ku/Ka Frequency Divider

With the rapid development of wireless communication technology,the integration of multiple passive devices together to form a multi-functional device has become an important research topic.As a combination of the filter and antenna,the filtering antenna can ensure the overall performance of the system and reduce the size of the passive circuit at the same time,which is in line with the trend of integrated miniaturization.As a very important part of satellite communications,earth station of satellite is still the bottleneck restricting the performance of the entire system after a rapid development in the past several decades.In the field of civil and military satellite communication systems,dual-band and multi-band antennas are usually needed.One of the key technologies to solve these practical problems is the use of dual-band shared feeding technology.This thesis focuses on the design of a filtering antenna and a dual-band frequency divider.A high gain wideband filtering antenna and a dual-band frequency divider operating in Ku and Ka-band are designed.Firstly,based on the study of traditional filtering antenna,a new type of filter antenna based on metasurface(MS)is designed and fabricated.Both simulation and measurement results show good antenna radiation and filtering performances.In this thesis,the working mechanism of the antenna is studied in detail,and its key parameters are studied.It is demonstrated that the impedance matching and filtering characteristic of filter antenna can be separately adjusted.By changing parameter values of different structures,the filtering characteristic of the upper and lower frequency bands can be independently controlled,which is beneficial to the design of the filter antenna.The filter antenna has a wide impedance bandwidth of 44.4%(4.14-6.5 GHz),an average gain of 7.5 d B in the pass-band,and a satisfactory filtering performance.The out-of-band suppression of the antenna is more than 17 d B in frequency band 0-8 GHz with a band rejection of up to 22 d B in 6.7-8 GHz.It is worth mentioned that no additional filter circuit is required in the proposed filter antenna,leading to no insertion loss of the filter element.Secondly,a novel dual-band frequency divider operating in Ku and Ka-band simultaneouslyis systematically studied and designed.A feasible design guideline is given to make thedesign process more efficient and time-saving.In this design,the profile of the circular waveguide changes gradually,resulting in higher degree of freedom.The coupling effect and the suppression of the higher order modes in the lower frequency band can also be taken into account at the same time.The low-pass filter is designed with a block mode filter,and a matching section is added at the coupling port to achieve good matching in the low frequency band.In Ku-band(11.45-11.70 GHz,12.25-12.75 GHz,13.75-14.50 GHz)and Ka-band(19.6-21.2 GHz,29.4-31.0 GHz),the voltage standing wave ratio is below 1.3,and the isolation between two out-put ports is better than 35 d B.The proposed frequency divider has a good performance in electrical performance,and it is compact in structure to meet the engineering requirements.Desirable frequency division performance is obtained as well.