基于慢波半模基片集成波导的紧凑型平衡滤波器设计

Design of Compact Balanced Filter Using Slow-Wave Half-Mode Substrate Integrated Waveguide

本文基于慢波半模基片集成波导(Slow-Wave Half-Mode Substrate Integrated Waveguide,SW-HMSIW)结构,设计了一款紧凑型平衡滤波器.该滤波器由金属盲孔阵列加载的SW-HMSIW多模谐振腔、两对间距0.5λ_(g)的差分馈电线(λ_(g)为滤波器中心频率处的波长)组成.该平衡滤波器由于利用了HMSIW多模谐振腔的不同模式,TE_(102)^(SW)和TE_(106)^(SW)两个模式工作在共模(Common Mode,CM)状态,而TE_(103)^(SW),TE_(104)^(SW),TE_(105)^(SW)这3个模式工作在差模(Differential Mode,DM)状态;因此该滤波器相较于已发表文献中的SIW平衡滤波器,具有更宽的工作带宽.进一步,慢波结构的引入实现了对HMSIW多模谐振腔不同模式谐振频率的调控,明显降低了谐振腔的纵向及横向尺寸,实现了滤波器的紧凑化设计.本文提出的滤波器,其总尺寸为1.86λ_(g)×0.34λ_(g),-3 dB DM工作相对带宽可达32%,-20 dB CM抑制相对带宽可达23%.与同类HMSIW平衡滤波器相比,本文提出的SW-HMSIW平衡滤波器的电路面积减小了约42%.

A compact balanced bandpass filter using just one half-mode substrate integrated waveguide(HMSIW)multimode resonator loaded with slow-wave structure is proposed.The filter is composed of a single-layer HMSIW multi⁃mode resonator,two pairs of differential feed lines and an array of metal blind holes.The TE_(103)^(SW),TE_(104)^(SW),and TE_(105)^(SW)modes of the HMSIW multimode resonator operate in differential mode(DM)and TE_(102)^(SW)and TE_(106)^(SW)modes operate in common mode(CM),resulting in the features of wide bandwidth.The introduction of slow-wave structure controls the resonant frequency of different modes,and realizes the filter miniaturization.A prototype is designed with a total size of 1.86λ_(g)´0.34λ_(g),the-3 dB DM fractional bandwidth of 32%at the center frequency of 6.5 GHz,and the-20 dB CM fractional suppression bandwidth of 23%.Compared with the previous HMSIW balanced filter,the circuit area of the proposed filter is reduced by 42%.