Recent developments in Liquid Crystalline Polymer (LCP) based processing technology showed that highly integrated, fully packaged RF front-end modules with high performance can be accomplished by using System-on-Package (SOP) approach. This paper presents the design of conformal monopole antennas on a very thin layer of flexible LCP, which can be fabricated as one of the layers in a multilayer LCP based substrate. The antennas can be bent, folded and rolled resulting in a compact design and integration of the antenna with the RF module package. The details of the fabrication and design of the antennas as well as the simulation and measurement data are presented in this paper. A method to increase the peak gain of the antenna is also proposed. Finally, the design of a 2.4/5.2 GHz dual band WLAN antenna with the RF-module package is discussed in the paper.