Abstract: Based on the theory of phasing-type single-sideband(SSB) modulators, a Ka-band SSB modulator was designed and fabricated, The theory of phasing-type SSB modulator is discussed, and the optimum performance is realized through the 3D electromagnetic analysis of passive circuits and the ADS integral non-linear circuit modeling. The results of 90° hybrid power divider and 0° power combiner under test can meet the design requirements for amplitude and phase shift. The test results show that the conversion gain of the modulator is less than -14dB, carrier wave suppression and image rejection ratio are more than 15dB,spurious wave suppression is more than 13dB, and the input 1dB impression point is more than 8dBm within the operation frequency band from 30GHz to 36 GHz, and its size is 18mm×6mm. The phasing-type SSB modulator doesn't need a complex band-pass filter, and characterizes with simple structure,high suppression of carrier frequency and tolerance of phase difference.