24 GHz Single-Balanced Diode Mixer Exploiting Cellulose-Based Materials

A 24 GHz single-balanced diode mixer in paper substrate is presented. The microstrip 180 degrees hybrid junction (rat-race) is fabricated exploiting a copper adhesive tape that is shaped by a photo-lithographic process and transferred to the hosting (paper) substrate using a sacrificial layer. Only three discrete devices are necessary for the mixer operation, namely: two low-barrier, Schottky diodes and a 0 Ω resistor, used as a jumper. The measurements show a conversion loss of about 10 dB at 24 GHz with a 50 MHz IF signal. At the same frequency the isolation between LO and RF ports is better than 35 dB. The record performance achieved demonstrates, for the first time, the feasibility of K-band mixers exploiting cellulose-based materials.