Patent ID: 8686297

Claim:
A flex circuit structure, comprising: a first flex circuit layer comprising one or more conductive trace layers configured to form a first layer of patterned conductive material; a second flex circuit layer comprising one or more conductive trace layers configured to form a second layer of patterned conductive material, wherein the first and the second layers of patterned conductive material are laminated together, and formed on opposing sides of the flex circuit structure and at least a portion of each is electrically isolated from each other by a dielectric layer to form a parallel plate capacitor, and wherein below a first frequency, the parallel plate capacitor has a high impedance value such that the corresponding portions of the first and second layers of patterned conductive material serve as independent first and second proximity sensor capacitor electrodes, and above a second frequency associated with a radio-frequency (RF) antenna signal, the impedance of the parallel plate capacitor is such that the first and the second layers of patterned conductive material are effectively shorted to each other to operate together as a unitary patterned conductor to act as an antenna resonating element, further wherein the first proximity sensor capacitor electrode is disposed on a first surface of the flex circuit structure and the second proximity sensor capacitor electrode is disposed on a second surface of the flex circuit structure; and an adhesive layer between the first and second layers of patterned conductive material, the adhesive layer including air paths.