In this paper, an improved wideband millimeter-wave 180° hybrid is proposed to apply to balanced mixers and multipliers. The proposed hybrid consists of a transition of standard waveguide to suspended coplanar waveguide (SCPW) and a transition of SCPW to suspended stripline. According to the inherent electromagnetic field characteristics of the two transitions, the proposed hybrid has merits of broadband power distribution and high isolation, which does not rely on resonant circuits. The measured insertion losses and isolation of two transitions at Ka-band are typically 1.4 dB and 25 dB, respectively. To verify the application of the proposed hybrid, A W-band single balanced mixer based on the hybrid has been designed and fabricated. The measured single-sideband (SSB) conversion losses of the fabricated mixer are less than 9.5 dB for the radio frequency (RF) range from 80 to 108 GHz. The presented hybrid has been proven to be efficient for the design of millimeter-wave balanced mixers and could be well applied in multipliers and other integrated circuits.
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