In this paper, a double-layered frequency selective surface(FSS) superstrate was proposed. The unit cell of the proposed FSS consists of a square slot and a Jerusalem cross structure, which are printed on two sides of the substrate. It is designed on the FR4 dielectric substrate with a relative permittivity of 4.8, loss tangent 0.025 and a thickness of 1.6 mm. The proposed structure shows excellent band-pass response with respect to different incidence angles. It was found that a band pass response occur at the Wi-Max resonant frequency of 2.5 GHz. The overall bandwidth of the simulated structure is 2.35 GHz. Performance evaluated by CST computer simulation. FSS is a metallic screen with frequency selective properties which are used as a spatial filters through which EM energy with a specific frequency range may be propagated.

Miniaturized band pass double-layered frequency selective superstrate for Wi-Max applications

This letter presents a novel wideband miniaturized-element frequency selective surface (MEFSS). The simulation and measurement results show that the bandwidth of the proposed MEFSS is remarkably enhanced compared to that of an original second-order MEFSS while its size and total thickness are still small. A parametric study is also conducted to understand the operating mechanism of the proposed structure. The phenomenon observed in the parametric study is explained with an equivalent circuit model.

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A Novel Wideband Miniaturized-Element Frequency Selective Surface

The capability of the capacitively loaded loop (CLL) metamaterial (MTM) superstrate to attenuate surface waves thereby reducing the back radiation of microstrip patch antennas is examined. To understand the surface wave suppression mechanism, theoretical approaches of a grounded dielectric slab waveguide is provided. Both theoretical and numerical analyses show that the proposed superstrate causes a drastic attenuation of surface wave propagation. To confirm the numerical simulations, the proposed antenna is fabricated and tested. The dimensions of the CLL-MTM covered patch antenna are 0.6λ × 0.8λ × 0.14λ. The radiated gain and efficiency are measured at 7.8 dB and 95%, respectively. Measurements show that the front-to-back ratio is enhanced by more than 12 dB. In comparison with the patch antenna without the CLL-MTM superstrate, the proposed antenna reduces the gain and efficiency by less than 0.1 dB and 2%, respectively.

https://ietresearch.onlinelibrary.wiley.com/doi/epdf/10.1049/iet-map.2018.6237

Microstrip patch back radiation reduction using metamaterial superstrate

In this paper, a Band Pass frequency selective surface(FSS) superstrate was proposed for the WLAN applications. Proposed FSS structure is made up of ring slot and a Jerusalem cross, which are etched on two opposite sides of the dielectric substrate. Structure is designed on the FR4 dielectric substrate with a relative permittivity of 4.4, loss tangent 0.025 and a thickness of 1.6 mm. The proposed structure shows excellent band-pass response with respect to different incidence angles. It was found that a band pass response occur at the WLAN resonant frequency of 2.4 GHz. 3 dB bandwidth of the simulated structure is 1.30 GHz.

A novel band pass double-layered frequency selective superstrate for WLAN applications

In this paper, we present the scattering characteristics of infinite and finite array using method of moment (MoM) with Floquet harmonics and asymptotic waveform evaluation (AWE) technique. First, infinite cylindrical dipole array is analyzed using the MoM with entire domain basis function and cylindrical Floquet harmonics. To provide the validity of results, we fabricated the cylindrical dipole array and measured the transmission characteristics. The results show good agreements. Second, we analyzed the scattering characteristics of finite array. A large simulation time is needed to obtain the scattering characteristics of finite array over wide frequency range because Floquet harmonics can`t be applied. So, we used the MoM with AWE technique using Taylor series and Pade approximation to overcome the shortcomings of conventional MoM. We calculated the radar cross section (RCS) as scattering characteristics using the proposed method in this paper and the conventional MoM for finite planar slot array, finite spherical slot array, and finite cylindrical dipole array, respectively. The compared results agree well and show that the proposed method in this paper is good for electromagnetic analysis of finite FSS.

Scattering analysis of curved FSS using Floquet harmonics and asymptotic waveform evaluation technique

In this paper, a double-layered frequency selective surface(FSS) superstrate was built and tested. The unit cell of the proposed FSS consists of a ring slot and a dipole-shaped structure and shows a complementary frequency response. Each unit cell is printed on two sides of a substrate. By using these double-layered structures, the first resonant frequency of the pass-band can be lowered. As a result, the size of the unit cell is minimized and the spacing between the other cells is reduced. The proposed FSS-dipole composite antenna is designed for the gain enhancement of wideband code division multiple access(WCDMA) frequency bands(1.92~2.17 ㎓) with a low quality factor(Q=0.17). To verify the gain enhancement performance of the FSS, an FSS-dipole composite antenna was created. Although the FSS layer enhances the gain of the primary radiation source of the dipole antenna, the FSS-dipole complex antenna cannot show a uniform gain over the entire desired frequency band. The experimental results show a gain enhancement of 3 dBi with an FSS superstrate in the WCDMA frequency band.

Double-Layered Frequency Selective Surface Superstrate Using Ring Slot and Dipole-Shaped Unit Cell Structure

This study presents a new, simple method for improving the front-to-back (F/B) ratio of a microstrip patch antenna. The back radiation of the microstrip patch antenna is reduced by removing some metallic parts around the ground plane and placing a new soft-surface configuration, consisting of an array of stand-up split-ring resonators on a bare dielectric substrate near the two ground plane edges. Compared to the F/B ratio of a conventional microstrip patch antenna with a full ground plane of the same size, our proposed microstrip patch antenna experimentally achieves an improved F/B ratio of 9.6 dB.

Hong-Min Lee

Papers

Double-Layered Frequency Selective Surface Superstrate Using Ring Slot and Dipole-Shaped Unit Cell Structure

Front-to-Back Ratio Improvement of a Microstrip Patch Antenna Loaded with Soft Surface Structure in a Partially Removed Ground Plane