W band single diode fundamental mixer with high intermediate frequency.

Abstract: The design approach of a W‐band single diode fundamental mixer is presented here. This mixer features planar structure easy for integrating and high intermediate frequency (IF). The mixer consists of a diplexer formed by a hammer‐head lowpass filter and a coupled line with open stubs, a broadband bandpass filter (BPF) using short stubs, a series diode, and the matching networks. This mixer covers IF signal up to 18 GHz by optimizing the frequency response of the diplexer, the radio frequency (RF) BPF, and the matching networks. Two open stubs are attached to both ends of the RF BPF, in order to add a transmission zero at local oscillator (LO) frequency. By this way, the required out‐of‐band rejection is fulfilled with lower order BPF, thus reducing the in‐band insertion loss. In addition, the coupled line with open stubs has low insertion loss at LO frequency, while having a transmission zero at RF frequency. All of the techniques above lead to a low loss high IF mixer. The measured conversion loss is 6.7–10 dB with 8–19 GHz IF and 82 GHz LO. [ABSTRACT FROM AUTHOR]