A Dual-Layer Frequency Selective Surfaces with Tunable Transmission and Fixed Absorption Bands

Area of Science:

• Electromagnetics and Metamaterials
• Microwave Engineering
• Applied Physics

Background:

• Frequency selective surfaces (FSSs) are crucial for controlling electromagnetic wave propagation.
• Existing FSS designs often lack dynamic tunability and multi-functional capabilities.
• The need for advanced FSS with integrated transmission and absorption is growing in wireless communications.

Purpose of the Study:

• To present a novel dual-layer FSS with integrated frequency division control.
• To achieve a tunable transmission window in the L-band and high absorption in a higher frequency band.
• To validate the design through simulations and measurements.

Main Methods:

• A dual-layer FSS architecture was designed and fabricated.
• The bottom FSS layer uses gradient gap square-ring elements with varactor diodes for tunable L-band transmission (1.26-1.9 GHz).
• The top FSS layer employs a square-ring-cross-slot topology for absorption (5.56-5.72 GHz), utilizing bottom layer reflection and dielectric losses.

Main Results:

• The L-band transmission window was successfully tuned from 1.26 GHz to 1.9 GHz with varactor modulation.
• Insertion loss within the transmission window remained below 1.41 dB.
• The structure achieved a peak absorption of approximately -30 dB in the 5.56-5.72 GHz band.

Conclusions:

• The proposed dual-layer FSS effectively demonstrates frequency division control with tunable transmission and high absorption.
• Measurement results closely agree with simulations, validating the design's performance.
• This FSS offers a promising solution for advanced electromagnetic applications requiring frequency agility and absorption.