Abstract-A novel uniplanar double-balanced mixer(UDBM) including coplanar wavegaide (CPW)-to-coplanar stripline (CPS) baluns as well as CPS high-pass and low-pass filters is designed and implemented. This mixer is simulated by an equivalent- circuit model, and its measured and simulated results are compared. The proposed mixer has conversion loss ranging from 6 to 10 dB and LO-to-IF and LO-to-RF isolations greater than 30 and 20 dB, respectively, and also provides broader LO and IF bandwidths of 10-35 GHz and 0.1-5 GHz, respectively.