Research On Novel Microstrip Filtering Power Dividers

Microwave passive components are indispensable parts of microwave communication and radar systems,whose performance and size have an important impact on the entire transceiver systems.Filtering power divider?FPD?,which can simultaneously paly function of frequency selectivity and power division,is receiving wide attention recently.In this thesis,the in-depth research on microstrip FPD is carried out,mainly focusing on innovative exploration of the physical mechanism and the new topology.The main content includes:1.A novel three-order quasi-elliptic bandpass FPD is proposed.In order to reveal its physical mechanism,the even-mode model is derived by using odd-/even-mode analysis method.According to the equivalence between the microstrip structures and the lumped–element counterparts,the lumped-element equivalent circuit of the even-mode model is obtained,and the equivalence relations are derived too.Therefore,the transmission property of the FPD is clearly explicated,which greatly simplifies the design process.In addition,as many as three resistors are joined to achieve matching of the outputs ports,thereby effectively improving the isolation.According to the proposed design method,a FPD operating at 1.99GHz is fabricated and measured.Compared to the existing quasi-elliptic bandpass FPD,the structure in this thesis has a wider 3-dB fractional bandwidth while ensuring the isolation better than 20 dB over a wide frequency range.2.A new dual-band FPD based on a FMR and a symmetric parallel-coupled three-line structure is proposed.The odd-and even-mode analysis and full-wave simulation analysis are used to analyze the resonance characteristics of the FMR,demonstrating four flexibly-adjustable resonance modes.Then,a dual-passband FPD is constructed based on the proposed FMR.The symmetric parallel-coupled three-line structure at the output ports plays the power division function,and the air-bridged resistors across its both ends effectively contribute to good isolation between two output ports.Meanwhile,an anti-parallel coupling line?APCL?structure is introduced into the resonator so that the FPD can create three transmission zeros,and its generation mechanism is analyzed in detail.3.A novel FPD topology based on substrate integrated waveguide?SIW?technology is proposed.In this thesis,two degenerate modes TE₁₀₂ and TE₂₀₁ of the square SIW cavity is studied.Then,two hybrid superposition modes TE_h¹?102,201?and TE_h²?102,201?formed by superposing TE₁₀₂ and TE₂₀₁ modes is proposed,to achieve the dual-function of filtering and power division.Based on it,a second-order SIW FPD operating at 7 GHz and a third-order SIW FPD operating at 9 GHz are designed.The two division path of the both designed SIW FPDs share a square SIW cavity.The odd-and even-mode model respectively excite TE_h¹?102,201?mode and TE_h²?102,201?mode,and resistors bridged across the slot along the symmetric plane of the FPDs are used to realize isolation between two output ports.Compared to the SIW FPDs in some published literatures,the one proposed in this thesis have significant advantages in terms of superior performance and compact size.