An Ultrawideband and High-Absorption Circuit-Analog Absorber With Incident Angle-Insensitive Performance

A high absorptance wide-band metamaterial absorber with metasurface and low-permittivity dielectric slabs

“…In this work, the dielectric layers h 2 and h 4 are PMI foam slabs with ε r of 1.05, top dielectric layer h 1 is FR4 with ε r of 4.4, the substrate of MS h 3 is PI with ε r of 3.5. As shown in figure 6(b), transmission and reflection coefficient of proposed MS, which is close to the −3.5 dB/−9.5 dB respectively in the range of 6.0-14.0 GHz, are like the resistive sheet with resistance 377 Ω/square and corresponds well with the design principles mentioned in [18]. Figure 6(c) shows the absorptivity of MS under four kinds of resistors configuration.…”

“…Multireflection interference will happen among them. As mentioned in [16][17][18][19][20], top dielectric layer can divide incident EM energy E into reflection energy E r , transmission energy E 2 and absorption energy E _FR4 . Then, MS will divide E 2 into absorption energy E 1 , reflection energy E 2_r and transmission energy E 3 .…”

“…The period P needs to satisfy 2 * Rad out < P < 2 * Rad out + λ U , where λ U is the wavelength of ending frequency of −20 dB reflection to avoid onset of free space grating lobes. Literature [18] mentioned the guidance of high absorption MS absorber design that 40% absorption of MS is the key factor. After assigning the initial values, by using the full-wave simulation software, the values of P, Rad out , Rad in , w, R out , R in achieve about 40% ohmic consumption of the incident plane wave energy in the designed frequency, are sequentially determined.…”

“…Different from [18], where the thicknesses of dielectric layers are calculated by the starting and ending frequencies of −20 dB designed absorption band, the thicknesses of dielectric layers in this work are designed based on other principles. As shown in figure 6(a), the starting 40% absorption frequency of large ring MS is at 5.70 GHz, that is set as the starting frequency of absorption enhancement.…”

“…To meet the requirements of broadband absorption, complicated unit cells or multi-metasurfaces (MS) structures are adopted, which lead to complex design and preparation processes [13][14][15][16][17]. Besides, our research group designed a ultrawide band and high absorption absorbing material with simple loop unit cell in [18]; however, the proposed UHAS uses too many chip resistors, which is expensive for large-scale applications.…”