Study On The Design Technique Of Microwave And Millimeter-Wave Filtering Power Divider

In recent years,with the vigorous development of wireless communication technology and the gradual upgrading of consumer applications,higher demands have been placed on devices with high integration,high performance and small size.The filtering power divider can realize the functions of power distribution and frequency selection at the same time,which has a positive impact on reducing system size,improving integration and reducing cost.According to the current research progress,it has certain technical difficulties and important engineering value to realize the specific filter response of the filtering power divider and ensure high isolation in the passband.At the same time,the emerging thin-film micro-nano processing technology provides further possibilities for the lightweight,miniaturization and high performance of RF microwave devices.This thesis starts from the basic design theory of power divider and filter,and designs several filtering power dividers with different working frequencies and structures based on specific technology.The feasibility of the design and related electrical properties are verified through simulation and tests.The main research contents and innovations of this paper are as follows:1.A filtering power divider working in the millimeter-wave frequency band is proposed.Based on the odd-and-even-mode analysis of the equally divided three-port network,the hairpin filter structure is used for the branch of the filtering power divider,and the filter response under the even-mode equivalent circuit is realized;one complex impedance isolation structure composed of several resistors and capacitors is designed.The structure realizes the port matching of the odd-mode equivalent circuit.Corresponding thin-film micro-nano processing technology is used to directly integrate the capacitor on the substrate.The filtering power divider works in the Ka-band,and the isolation in the passband is greater than 17 d B.2.A filtering power divider design with inductive isolation structure is proposed.Multiple transmission zeros are introduced through the cross-coupling filter structure and the 0°feed structure,which improves the roll-off rate of the transition band and the suppression performance of the stopband.The design idea in 1 is adopted to apply the filter structure to the branch of the filter power divider.A complex impedance isolation structure composed of resistance and inductive microstrip lines according to its structural characteristics is designed.Finally,the filtering power divider with the center frequency at 16 GHz and the best isolation point reaching 20 d B is realized.A planar size of 7.4mm×4.4mm(0.73λ_g×0.44λ_g)is achieved by adjusting the layout of the resonator.3.In order to achieve further miniaturization,the key structure of the three-dimensional integrated device is studied,and a stacked low-pass filtering power divider is designed.The stepped-impedance hairpin low-pass filter is stacked and arranged as a branch by using the stacked substrate process,which effectively reduces the size,and the isolation resistor is directly integrated into the substrate according to the corresponding thin-film processing technology.Through the optimization of structural parameters and resistance values,the 3-d B cutoff frequency of the low-pass filtering power divider is 5.8 GHz,the optimal isolation in the passband exceeds 20 d B,and the rejection in the stopband from 7.5 GHz to 20 GHz is greater than 20 d B.The planar size is4.5 mm×4.2 mm(0.225λ_c×0.21λ_c).