Investigation of Enhancement Band Using Double Screen Frequency Selective Surfaces with Koch Fractal Geometry at Millimeter Wave Range

Abstract

Numerical and theoretical investigations are presented for a double screen frequency selective surface (DSFSS) with perfectly conducting Koch fractal patch elements. The work was developed in two steps, in the first step two Koch fractal FSS screens were designed using the commercial software Ansoft Designer TM . In the second these FSS were cascaded and separated by an air gap layer, forming the so-called DSFSS, to improve the bandwidth behavior. Thereafter, a numerical cascading technique is used to analyze the effect of the air gap on the DSFSS. The results were compared and a good agreement was observed.

A Tri-Band Frequency Selective Surface (FSS) to Diplex Widely Separated Bands for Millimeter Wave Remote Sensing

“…Thus, it can be used in the quasioptical receiver setup. Decreasing the unit cell size using miniaturization techniques will also provide angle stability, but due to fabrication challenges, it is not well suited in the millimeter wave regime [12,13]. The frequency response of the fabricated FSS in Fig.…”

“…However, embedded unit cell designs using similar resonant elements offer multi-band operation only for a fixed frequency separation ratio between the adjacent bands [9][10][11]. Multi-band operation with closely spaced frequency windows (FWs) has been reported for these resonant shapes using convolution and fractal miniaturization techniques at microwave and terahertz frequencies [12,13]. The unit cell designs investigated below 20 GHz are not feasible for tri-band operation in the millimeter wave frequency due to the widely separated FWs spanning 50 to 200 GHz, varying bandwidth requirement in each frequency window, and challenges associated with the fabrication of the miniaturized FSS using microfabrication techniques.…”

Frequency Selective Surfaces: A Review

“…However, the proposed structure is exceptionally compact and low-profile having a functional frequency of about 3.8 GHz and applicable to very low-frequency applications. Furthermore, Figure 10b shows fractal Koch elements of different levels used in a double layer FSS [97] and Figure 10c gives the topology of a three layer FSS proposed in [98] based on fractal complementary elements. Table 4 demonstrates a comparison of different multilayer FSS presented in recent researches, and it is observed that achieving higher FBW is a challenge with smaller unit size and reduced profile.…”

“…FSSs have been used in various applications ranging in different frequency bands from RF, micro-, millimeter wave, and terahertz regions [97,114,115]. Some of the researches are well demonstrated in radio frequency identifications [9,116], wireless communications [117,118], shielding purposes/EMI/EMC problems [58,81,82,119], polarization transformation [120], stealth radomes [75,98,103,121], EMI protection from portable electronics/wireless charging pad [122,123], directional multi-band antenna [124], polarization detection [125], and sensing [28,126].…”

Synthesis of Multiband Frequency Selective Surfaces Using Machine Learning With the Decision Tree Algorithm

“…Usually, the frequency behavior of the FSS depends on the geometry of the planar array elements, periodicity of the array, relative permittivity and thickness of the dielectric substrate, incident wave polarization, and incidence angle. Recently, the FSS geometries are being used in many system applications, such as radar, satellite, wireless communication, and chipless RFID, at microwaves and millimeter waves [2], [3].…”