Composite Metamaterials for THz Perfect Absorption

Abstract

The design, characterization, and experimental demonstrations are presented for triple-band, near-perfect, composite metamaterials that absorb in the terahertz regime. Three absorption peaks are observed at 0.537 THz, 0.948 THz, and 1.59 THz with the respective absorption coefficients of 0.957, 0.988, and 0.96. The effect of spacer thickness on absorption is analyzed with interference theory, and the conditions for unity absorption are obtained via comparison of amplitude and phase. The effect of the length (l) of four outer parts of Jerusalem cross on the absorption is analyzed via transmission line theory. Furthermore, the absorption effects of capacitance and inductance caused by the changing l are examined. The calculated multi-band transmission line model corresponded well to simulations. The effect of the outside length on the absorber performance is further explained by electric field distributions, which is experimentally confirmed. Overall, the consistent conclusions provide design guidance for metamaterial absorbers, or the realization of tunable absorbers, and provide a further understanding of the mechanisms.

A Bidirectional Ensemble‐Learning Framework for Target‐Oriented Metamaterial Designs

“…We only focus on the geometric dimensions of the structure on the top layer of the absorber, so this is a 2D object design with a triple‐band absorption spectrum. [ 41 ] As shown in Figure a, we trained ELF with over 13 000 groups data for the last complex structure. The forward prediction mean square error is 0.0000894 (in Figure 6b).…”

“…For instance, most meta‐atom designs stipulate a uniform refractive index, lattice size, and height, but allow varying geometric size. [ 39–41 ]…”

“…For instance, most meta-atom designs stipulate a uniform refractive index, lattice size, and height, but allow varying geometric size. [39][40][41] During the modeling process, all metallic portions of the metamaterial absorber model are set as gold, while their inner radius of the ring, material dielectric constant, and thickness of dielectric spacer (Figure 3a), unit period are considered as design variables. The meta-atoms are arranged in rectangular lattices.…”

A Compact and High‐Gain Omnidirectional Antenna‐Based Coding Metasurface Ground for Unmanned Aerial Vehicles Applications

“…Circular patch antennas and circularly periodic mushroom units make up the antennas. [ 2 ] Unfortunately, the majority of monopole antennas have such a high profile and a low‐elevation angle radiation pattern, making them unsuitable for large metallic vehicle communication. UAVs have gotten a lot of press for military, industrial, and scientific uses.…”

Coding Artificial Magnetic Conductor Ground and Their Application to High‐Gain, Wideband Radar Cross‐Section Reduction of a 2×2 Antenna Array

“…In addition to the antenna configuration, the structural backscattered energy of the antenna depends on the airplane over which it is installed. [ 1–3 ] The practical techniques include cancellation of a wave coming into the radar or of the sensor‐based system by destructive interference with the scattered field. This is because there are no reflections from the feed in such a situation and backscattering of the antenna is due to its layout only or, to put it another way, the structural backscattered energy of the antenna depends on the currents induced by the incident wave above the surface of the antenna.…”