Synthesis of Ultraminiaturized Frequency-Selective Surfaces Utilizing 2.5-D Tapered Meandering Lines

An ultraminiaturized bandstop frequency-selective surface (FSS) utilizing two-dimensional (2-D) tapered meandering lines (TML) along with vertical vias is proposed. Full-wave simulations, equivalent circuit modeling, and analytical results are presented for the designed FSS. A prototype 2.5-D TML-FSS is fabricated, and its performance is measured in an anechoic chamber for various incident angles in both the transverse-electric (TE) and transverse-magnetic (TM) polarizations. Measured results are in agreement with the simulated ones, indicating the authenticity of the design process. Unit cell size of the proposed FSS is only 2.9% of the free-space wavelength at resonant frequency and has a fractional bandwidth of 20.9%. Furthermore, the proposed design is modified to convoluted 2.5-D TML-FSS and interdigitated 2.5-D TML-FSS to give different unit cell sizes in terms of wavelength with different fractional bandwidths.