Broadband Microwave Absorption Properties of a Frequency-Selective Surface Embedded in a Patterned Honeycomb Absorber

Abstract : In this article, a patterned honeycomb absorber (PHA) with an embedded frequency-selective surface (FSS) was proposed for broadband applications. The impedance of the FSS embedded in a homogeneous honeycomb absorber (HA) was first analyzed, which suggested that directly combining an FSS with a homogeneous HA was unreliable. Subsequently, a PHA was developed to adjust the input impedance. Using the PHA, an FSS embedded in patterned honeycomb absorber structure with a wide absorption band was developed. The consistency between the simulated and measured results verifies the analysis and design principle. The proposed absorber may be very suitable for various microwave applications owing to its low cost, lightweight, high strength, and environmental friendliness.

 EXISTING SYSTEM :

 ? In this paper, the physical model of electrically thin weakly conductive film with intrinsic surface impedance is established, indicating that the imaginary part of high surface impedance is non-negligible at microwave frequencies. ? The measurement is provided to verify the validity of the equivalent relationship and the reliability of the full-wave model. ? This study provides a new way to reduce the thickness of absorber, exhibiting promising potential for stealth technique. ? In order to further increase the bandwidth and reduce the thickness, Circuit Analog (CA) absorber have been extensively studied. ? In the design of patterned lossy FSSs, researchers have conducted an in-depth study of equivalent circuits with different topologies and their equivalent impedance characteristics.

 DISADVANTAGE :

 ? These aforementioned problems force the designer to seek an alternative method for designing the ultra-wideband absorbers. ? This is the most challenging problem in using conventional resonating FSS elements for designing of UWB absorbers. ? Other problems related to resonant elements are the harmonics of the fundamental resonance and the antiresonant frequencies which show their effects when the bandwidth becomes sufficiently large. ? with a few numbers of resistive FSS layers is a challenging problem. Resonating FSSs such as cross and loop elements, common in designing moderate bandwidth absorbers, are not suitable for this application. The first problem is selecting the proper dimensions for the resonant elements.

 PROPOSED SYSTEM :

 • The proposed ultra-thin absorber can provide -10 dB reduction over the frequency range of 4.5–13.3 GHz. • Taking advantage of the imaginary part of intrinsic surface impedance, the thickness is further reduced by introducing a patch pattern, on which a double ring structure is introduced to expand the low-frequency absorption performance. • The fully printed single-layer double-side ultra-thin absorber is proposeded. • The -10 dB absorption bandwidth is from 4.5 GHz to 13.3 GHz and total thickness is 4.05 mm, which is close to the theoretical limit of lowest operating frequency thickness: ??=??max/17.2d=?max/17.2

 ADVANTAGE :

 • A comparison of achievable bandwidth performance for an ultra-thin resonant absorber comprising of air, dielectric or magnetic substrates. • The absorbing structure allows obtaining remarkable performance (-15 dB in the band from 7 GHz to 20 GHz) with an overall thickness of only 5 mm. Commercial Jaumann screens with similar performance are characterized by larger thicknesses. • The performance of the described absorbers based on resonant FSS structures is acceptable up to 30/40 degrees since they are not optimized for oblique incidence angles. • In order to be able to simulate the electromagnetic properties of the synthesized design for verifying the performance of the obtained absorber, it is required that the periodic layers have commensurate periodicities.