The miniaturization of gain equalizer has been becoming the main tendency of theequalizer's research and development.This paper designs a half mode substrate integrated waveguide (HMSIW) equalizer which has seven layers structures and multiplecascaded substructure units

and the resonant unitsand transmission line distribute at three-layers dielectric substrates

working at Ku waveband.The transition design of multimicrostrip line segments impedance matching is proposed and the dominant mode of HMSIW resonant cavity is gotten based on coordinate transform theory.The design method is summarized.Compared with microstrip equalizers

this structure has higher

Q

-factor and lower loss.What's more

w

ith the use of absorbing pillar arrays

the attenuation and

Q

value can be easily tuned;test result shows that it has smaller size than the traditional cavity equalizers with the same performance

the measured curve and simulation curve are in good agreement

and the maximum error is 0.6dB.The output gain fluctuation of TWTA is less than 0.4dB with the equipped HMSIW equalizer.