Multilayer Inkjet Printing of Millimeter-Wave Proximity-Fed Patch Arrays on Flexible Substrates

Flexible inkjet-printed proximity-fed patch antennas, designed for the 24-GHz Industrial, Scientific, and Medical (ISM) band, are demonstrated in this letter for the first time featuring a multilayer inkjet deposition process. Inkjet printing of antennas allows for the low-cost, noncontact, and additive fabrication of RF components onto nearly any host substrate or package. The inkjet-printing process exhibited in this leter is the first inkjet process to demonstrate multilayer printed antennas, enabled by a new printable dielectric ink that allows for the deposition of thick dielectric layers. Printed coupled patch antennas with realized gains of over 4 dBi and four-element coupled patch arrays with gains of over 7 dBi are demonstrated on a flexible liquid crystal polymer (LCP) substrate. The antenna gain, return loss, and pattern are presented and demonstrate the repeatability and design flexibility of the novel inkjet-deposition process.