Flexible Dual Flower-Shaped FSS for Conformal Applications With Low Aberration of Far-Field Pattern

In this article, a novel conformal frequency selective surface (FSS) with dual reflection bands located at X and Ku bands and a transmission window near 12 GHz is proposed, which brings little aberration in the far-field pattern. The unit cell consists of double flower-shaped strips on an ultrathin dielectric slab. The equivalent circuit model is established by the field distributions to illustrate the resonant mechanism, the parameters of which are calculated. The planar and elliptic cylindrical samples are fabricated and tested. The test results are consistent with simulation data. The two samples’ averages of shielding effectiveness are no less than 16 dB. The insertion losses of the planar and the curved FSS are less than 1 dB in the passband. The near-field distributions in three concerned bands are scanned. The conformal FSS excites slight distortion in the passband but stirs the distributions into a mess, the electric field intensity of which drops by 20 dB in the stopbands. Moreover, the absolute gains in the passband are tested in compact antenna test range. The far-field pattern is also evaluated by near-field to far-field method. The data obtained by two methods is consistent with the simulation. Little aberration by the FSS occurs in the passband, and the average gain's deviation is no more than 0.64 dB.