A Wideband Wide-Angle Ultra-Thin Metamaterial Microwave Absorber

Abstract

Abstract-A novel design of wideband, ultra-thin, wide-angle metamaterial microwave absorber has been presented. The unit cell of the proposed structure is designed by using parametric optimization in such a way that absorption frequencies come closer and give wideband response. For normal incidence, the simulated FWHM bandwidth of the proposed structure is 1.94 GHz, i.e., from 5.05 GHz to 6.99 GHz and −10 dB absorption bandwidth is 1.3 GHz from 5.27 GHz to 6.57 GHz. The proposed structure has been analyzed for different angles of polarization, and it gives high absorption (more than 50%) for oblique angles of incidence up to 60 • . The designed absorber is in low profile with a unit cell size of λ 0 /6 and ultrathin with a thickness of λ 0 /32 at the center frequency of 5.92 GHz corresponding to 10dB absorption bandwidth. The current and electromagnetic field distributions have been analyzed to understand the absorption mechanism of the absorber. An array of the proposed absorber has been fabricated and experimentally tested for various polarization angles and oblique incidences of electromagnetic wave. The proposed absorber is well suited for surveillance and other defense applications.

A compact ultra‐thin ultra‐wideband microwave metamaterial absorber

“…The wideband absorption of 8.30 GHz above 90% absorption was achieved using diagonally placed simple patches and dielectric substrate of thickness 3.2 mm . Subsequently, a metamaterial absorber of thickness λ 0 /32 (λ 0 is the free space wavelength) with 1.3 GHz absorption was obtained . Later, a structure with λ 0 /18 thickness and more compact than the earlier design was proposed with an absorption bandwidth of 3.75 GHz above 90% absorptivity.…”

“…[11][12][13][14] Nowadays, wideband absorption with ultra-thin structure is essential in many metamaterial absorber applications. Thus, metamaterial absorber with multi-layer, 15,16 multiresonant, 17,18 and single layer [19][20][21][22][23][24][25][26] structures have been proposed for wideband absorption. Although, multilayer and multiresonant structures provide wideband absorption, they suffer from thickness and large size, respectively.…”

Comment on "A Wideband Wide-Angle Ultra-Thin Metamaterial Microwave Absorber"

“…al. [12]. It is found that the absorptivity for the proposed structure is less than 22.3% within operating frequency band of 4 GHz to 8 GHz.…”

“…This fact is addressed by the articles respectively [7][8][9][10][11]. In subsequent section, study and investigations are carried out on the structure proposed in [12], and it is shown that already reported structure is not a metamaterial absorber. al.…”

“…This low value of absorption is obtained due to consideration of cross-polarized reflections in the calculations of absorptivity. The original authors in [12] may have ignored this fact and found very high absorption over wide bandwidth. We have plotted co-polarized and cross-polarized reflectances as shown in Fig.…”