Microstrip Antenna Arrays on Multilayer LCP Substrates
- Friday, 02 February 2007
Antennas, feedlines, and switches are embedded in and on flexible sheets.
A research and development effort now underway is directed toward satisfying requirements for a new type of relatively inexpensive, lightweight, microwave antenna array and associated circuitry packaged in a thin, flexible sheet that can readily be mounted on a curved or flat rigid or semi-rigid surface. A representative package of this type consists of microwave antenna circuitry embedded in and/or on a multilayer liquid- crystal polymer (LCP) substrate. The circuitry typically includes an array of printed metal microstrip patch antenna elements and their feedlines on one or more of the LCP layer(s). The circuitry can also include such components as electrostatically actuated microelectromechanical systems (MEMS) switches for connecting and disconnecting antenna elements and feedlines. In addition, the circuitry can include switchable phase shifters described below.
Figure 1 depicts a prototype three- LCP-layer package containing two four-element, dual-polarization microstrip patch arrays: one for a frequency of 14 GHz, the other for a frequency of 35 GHz. The 35-GHz patches are embedded on top surface of the middle [15-mil (≈0.13-mm)-thick] LCP layer; the 14- GHz patches are placed on the top surface of the upper [9-mil (≈0.23-mm)- thick] LCP layer. The particular choice of LCP layer thicknesses was made on the basis of extensive analysis of the effects of the thicknesses on cross-polarization levels, bandwidth, and efficiency at each frequency.