Conformal Antennas on Liquid Crystalline Polymer Based Rigid-Flex Substrates Integrated With the Front-End Module

Recent developments in liquid crystalline polymer (LCP)-based processing technology have shown that highly-integrated, fully-packaged radio-frequency (RF) front-end modules with high-performance can be designed by using the system-on-package (SOP) approach. However, the direct integration of a large antenna element to a small module package still remains an issue. This paper presents a novel conformal antenna structure, which results in a compact integration of the antenna and the module package for 5 GHz WLAN/WiMAX applications. The extension of 5 GHz single-band operation to 2.4/5 GHz dual-band operation is also discussed in this paper. The antenna is an inverse L-shaped monopole printed on a 25-mum-thick flexible LCP layer, which protrudes from a rigid multilayer organic substrate. The shielding effects of a grounded metal case, which can house the associated module circuitry, are also considered during the design process. The metal case serves as a vertical ground plane for the antenna in addition to protecting the module circuitry from the near-fields of the antenna. The flexible LCP substrate can be bent and folded over the module case, resulting in a compact design and the tight integration of the antenna with the front-end module. The details of the design and the fabrication of the proposed structure as well as the simulation and the measurement data are presented in this paper.