Numerical analysis of flexible ultra-thin conformal antenna array
We present a flexible ultra-thin conformal patch antenna array operating in the Industrial, Scientific, and Medical (ISM) band (2.4-2.4835 GHz) for wireless sensor nodes. The antenna was designed on a flexible polyimide film (Kapton HN) substrate with the size of 95180.1 mm3 and the number of 7 radiating elements. The antenna exhibits S11 < -10 dB at the band of interest with broadband behavior. The measured gain is 4.72 dB in vertical polarization at 2.48 GHz. To obtain the maximum gain of the array, distances of the elements in the array are optimized by using the genetic algorithm (GA) in conjunction with the multilevel fast multipole algorithm (MLFMA). The VSWR is less than 2 over 2.408-2.555 GHz, frequency band. The method of moment (MOM) based on the electric field integral equation (EFIE) is applied to analyze the radiation characteristics of the proposed antenna. The resulting matrix equation obtained by the discretization of the EFIE is solved iteratively using the MLFMA. The radiation patterns and return loss obtained from numerical analysis and simulations show a good impedance matching and a gain enhancement of the proposed antenna.