Low profile polarization‐insensitive wideband rasorber with in‐band transmission

Abstract

A dual-polarized wide-band rasorber with in-band transmission has been presented in this study. Our proposed design comprises a modified swastika design on the upper layer and a square slotted design on the bottom layer. The top layer is loaded with lumped resistors on the top pattern in an even manner resulting in broadband absorption. The square slot designed on the lower layer is accountable for in-the-band transmission. The total thickness of the design is only 0.058 λ L (λ L corresponds to the lowest frequency) and possesses strong fractional bandwidth of around 124%. The whole design shows a wideband absorption whose reflection coefficient is less than À10 dB from 1.7 to 7.25 GHz, and an insertion loss of 0.6 dB in the transmission band at 4.9 GHz. The originality of the proposed design lies in its miniaturized design, good angular stability, high fractional bandwidth, and dual-polarized response. For a comprehensive analysis, we have investigated the distribution of surface current, its corresponding circuit model, and several other parameters. Finally, the prototype has been fabricated and validated, it has been found that there is a decent agreement between measured and simulated responses.

Polarization-insensitive graphene-based THz rasorber with ATA characteristics

“…In the first step, a bandpass FSS is designed using a square ring engraved in the metallic bottom layer. The dimension of the unit cell is selected in such a way as to obtain the desired bandpass response at a frequency of around f T [1,10]. Figure 4(a) depicts the geometry of the bottom FSS layer and its S-parameters response illustrated in figure 4(d).…”

“…In this section, an ECM is developed using transmission line theory to get better insight into the working mechanisms of the designed rasorber [5,10,29,36]. The ECM of the designed rasorber is illustrated in figure 9(a).…”

“…Out-of-band reflection can be decreased by installing a band-stop lossy structure on the radome, but high in-band transmission must also be guaranteed for the system to function properly. The FSS rasorber can be classified into three different categories in terms of their frequency response and placement of transmission (T), and absorption (A) bands [6]: (i) The transmission band is followed by the absorption band (TA-configuration) [7], (ii) The absorption band is followed by the transmission band (AT-configuration) [4,8], and (iii) The transmission band lies between the two absorption bands, i.e., absorption-transmission-absorption (ATA-configuration) [2,3,5,[8][9][10][11]. Amongst these configurations, the ATA FSS has received the highest attention because of its frequency response, which is more suitable for practical applications.…”

“…Rasorber serves in variety of applications, viz., stealth technology, reducing the radar cross-section (RCS), and mutually interference-free communication among different subsystems [11]. The microwave rasorber embodies lumped circuit elements like resistance and varactor-diode to make the top layer a lossy nature to minimize the out-of-band reflection [2,5,[10][11][12]. The integration of these in the 0.615 to 0.719 THz band providing a fractional bandwidth of around 29%.…”

“…After optimizing the dimensions of the FSS-4 using CST simulation, desired response characteristics are obtained with a transmission band around = f 0.THz and two sides reflection (see figures 5(a) and (b)). A generalized band-stop FSS ECM is developed, as shown in figure 6(b)[5,8,10]. The performance of band-stop FSS is…”