Abstract
We present an active frequency selective surface (AFSS) consisting of a curved composite structure that provides structural stability and robustness. The proposed structure can operate on either the C-band (OFF state) or X-band (ON state) by controlling the PIN diode located between the cross-shaped loop and the inductive stub on the surface. Moreover, it minimizes parasitic couplings through grid-type on/off bias circuits and via holes. Thus, the AFSS guarantees isolation from the unit cell, which is a downside of a previous control technique called reconfigurable frequency selective surface. We analyzed the impact of composite structures and the three-dimensional shape on the AFSS transmission with a foam-core sandwich structure, which is light and mechanically strong, by considering conditions of a real application environment.
Highlights
A frequency selective surface (FSS) is an electromagnetic structure that resonates with a specific frequency, exhibiting a corresponding impedance derived from its capacitance and inductance, and it selectively transmits or reflects the frequency of incident electromagnetic waves [1]
The proposed structure has a four-legged loaded element pattern on the dielectric substrate, which is known to have a stable frequency response according to the incidence angle of the incident and polarized waves, a via hole connected to its bottom face, which is used for the diode power supply, and a function to reconfigure the operating frequency depending on the PIN diode located between the cross-shaped loop and the Pi-shaped slot stub
To verify the transmission loss according to frequency in the active FSS (AFSS) structure, we thoroughly examined the frequency response for varying incidence angles of 0∘, 30∘, and 60∘ for the TE and TM modes, which are different when the PIN diode is in short circuit and in the ON state
Summary
A frequency selective surface (FSS) is an electromagnetic structure that resonates with a specific frequency, exhibiting a corresponding impedance derived from its capacitance and inductance, and it selectively transmits or reflects the frequency of incident electromagnetic waves [1]. Conventional FSSs present a limitation when applied to modern multifunctional and complex systems, as they constitute a passive circuit operating on a single frequency band To address this problem, researchers have developed the active FSS (AFSS), which can operate on different frequency bands [4, 5]. We employed a commercial PIN diode that provides simple activation and deactivation Using these elements, we designed a four-legged loaded AFSS structure for transmission in either the X- or C-bands, depending on its state, ON or OFF, respectively. We designed a four-legged loaded AFSS structure for transmission in either the X- or C-bands, depending on its state, ON or OFF, respectively This structure gained impedance and stability with respect to the incidence angle and distance between the unit cell and bias circuits given its composition, which includes the diode, symmetric, and bias circuits, for a grid-type power supply. To verify the design results, we analyzed the impact of the dielectric properties and curvature radius of the composite materials through electromagnetic transmission measurements
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