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Proceedings ArticleDOI

Miniaturized-element frequency selective surfaces with narrowband, higher-order bandpass responses

TL;DR: In this paper, the minimum gap spacing and trace widths are determined by the minimum feature size that can be reliably fabricated using standard PCB lithography techniques, which is the bottleneck of achieving high quality-factor resonators.
Abstract: The selectivity and response type of the frequency response of a frequency selective surface (FSS) are important factors that determine the suitability of an FSS for a given application. A common application of FSSs is to use them to shield sensitive electronic devices form unwanted interference or jamming signals with frequencies close to the main transmission band of the device. In such situations, spatial filters with highly-selective and narrowband transmission windows are required. FSSs with higher-order bandpass or bandstop responses acts similar to coupled-resonator filters. Therefore, their operational bandwidths are inversely related to quality factors of their resonators. Thus, to achieve a narrow-band response, higher quality factors are needed. For the case of traditional FSSs, these resonators are created using resonant elements within a unit cell. Miniaturized-element frequency selective surfaces (MEFSSs), on the other hand, use the combination of non-resonant reactive surfaces with capacitive and inductive surface impedances to create distributed-type resonators. For both approaches, the minimum-attainable feature sizes used in the metallic patterns of the structures are the bottleneck of achieving high quality-factor resonators. In practice, the minimum gap spacing and trace widths are determined by the minimum feature size that can be reliably fabricated using standard PCB lithography techniques. Therefore, achieving very high-quality factors and accordingly narrowband frequency responses for both configurations is rather challenging.
Citations
More filters
Journal ArticleDOI
TL;DR: In this article, two miniaturized resonant surfaces coupled by a nonresonant inductive layer are used to build a second-order bandpass frequency selective surface (FSS).
Abstract: High-order bandpass frequency selective surfaces (FSSs) (N ≥ 1) can achieve high performance with a flat in-band frequency response and fast roll-off. One particular practical issue of designing bandpass FSSs using resonant surfaces is that the thickness of the substrate would be around a quarter of a wavelength. On the other hand, the size of a nonresonant FSS array element is usually large. A new miniaturized FSS capable of exhibiting a second-order bandpass response is proposed in this letter. Two miniaturized resonant surfaces coupled by a nonresonant inductive layer are used to build the proposed FSSs. An FSS operating at around 3.8 GHz is designed to verify the method. The element size is smaller than 0.076λ × 0.076λ for the proposed structure. This is significantly smaller than the element size of second-order FSSs designed using conventional approaches. The overall thickness is less than λ/24, where λ is the free-space wavelength at the resonant frequency. The method could be particularly useful for the design of FSSs at lower frequencies with longer wavelengths.

65 citations

Journal ArticleDOI
TL;DR: In this article, the capacitance and inductance of elementary periodic structures with capacitive and inductive surface impedances over a wide range of values are analyzed using three mechanical tuning techniques: overlapping combined with relative movement, stretching/compression, and flexure.
Abstract: We present techniques for designing large-scale, mechanically tunable periodic structures (PSs). Overlapping combined with relative movement, stretching/compression, and flexure are the three mechanical tuning techniques studied in this paper. We demonstrate that all of these mechanical movements may be used to tune the capacitance and inductance of elementary periodic structures with capacitive and inductive surface impedances over wide ranges of values. Analytic formulas for calculating the variable inductance and capacitance of these tunable PSs are also provided. These elementary PSs are the building blocks of a wide range of other PSs with more complicated unit cells and response types. One such structure—a frequency selective surface (FSS) composed of series combination of these inductive and capacitive structures—is also examined to demonstrate the application of the proposed tuning and analysis concepts. The FSS is fabricated on an accordion-like substrate that can be contracted or stretched to change its frequency of operation. The response and tuning properties of this structure are experimentally characterized using a free-space measurement system. A very good agreement between theory and experiment is obtained. This demonstrates that the behavior of such complex mechanically tunable PSs can be analyzed by examining the behavior of their constitutive inductive and capacitive elements.

30 citations


Cites background from "Miniaturized-element frequency sele..."

  • ...Examples include microwave lenses [9]–[12], reflectarrays [13], [14], and miniaturized-element frequency selective surfaces [33]–[46]....

    [...]

Journal ArticleDOI
TL;DR: In this paper, a new architecture for a miniaturized-element frequency selective surface (MEFSS) capable of providing a third-order bandpass response is presented and experimentally verified.
Abstract: A new architecture for a miniaturized-element frequency selective surface (MEFSS) capable of providing a third-order bandpass response is presented and experimentally verified. The proposed MEFSS consists of three metal layers separated from one another by two dielectric substrates. The exterior metal layers are nonresonant inductive wire grids, while the center layer is a hybrid resonator composed of an inductive wire and an I-shaped resonator. The exterior metal layers and the dielectric substrates act as two inductively coupled series resonators sandwiching the hybrid resonator layer in the middle. This results in a filter with a third-order bandpass response that can also provide an out-of-band transmission null at a frequency higher than that of the main passband. An equivalent-circuit-based synthesis procedure for this MEFSS is also presented in this letter that allows for designing the FSS from its desired system-level performance indicators (e.g., center frequency of operation, bandwidth, etc.). The validity of this design procedure is verified by presenting a design example and conducting full-wave electromagnetic simulations. Finally, an experimental proof-of-concept demonstration is performed by characterizing the unit cell of this MEFSS designed to operate in a WR-112 waveguide environment.

25 citations


Cites background or methods from "Miniaturized-element frequency sele..."

  • ...Using only inductive wire grids in [11] allowed for significantly reducing the period of the structure, which in turn resulted in a stable response over a very wide field of view....

    [...]

  • ...Moreover, we recently reported two inductively coupled MEFSS architectures that use nonresonant inductive wire grids and dielectric substrates to achieve highorder bandpass response for both single- [11] and dual-band [12] filters....

    [...]

  • ...Specifially, the proposed device builds upon the architecture presented in [11] and allows for achieving a high-order bandpass response without the need for increasing the number of transmission-line resonators used in the architecture....

    [...]

  • ...In this letter, we present a new MEFSS architecture, which addresses this shortcoming of the design presented in [11]....

    [...]

Journal ArticleDOI
TL;DR: In this article, a millimeter-wave frequency selective surface (FSS) is presented for demultiplexing four atmospheric remote sensing bands with varying bandwidth (3-20 GHz) and frequency separation (50-195 GHz).
Abstract: A novel millimeter-wave frequency selective surface (FSS) is presented for demultiplexing four atmospheric remote sensing bands with varying bandwidth (3–20 GHz) and frequency separation (50–195 GHz). The unit cell (670 μm × 670 μm) is a circular metal mesh loaded with a monopole integrated concentric ring on a 175-μm-thick quartz substrate designed to reject 50–60 GHz (B1), 87–91 GHz (B 2), and 148–151 GHz (B3), and transmit 175–195 GHz (B4) for transverse electric (TE) and transverse magnetic (TM) polarizations at oblique incidence (25°−35 °). Transmission response of the cascaded FSS measured using a continuous-wave terahertz source showed insertion loss of 15 dB and higher in the reflection windows (B1, B2, and B3) and less than 0.5 dB in the transmission window (B4) for TE and TM polarizations at 30° incident angle.

12 citations


Cites background from "Miniaturized-element frequency sele..."

  • ...However, this does not reduce the alignment error [12] between the cascaded FSS layers....

    [...]

References
More filters
Journal ArticleDOI
TL;DR: In this article, two miniaturized resonant surfaces coupled by a nonresonant inductive layer are used to build a second-order bandpass frequency selective surface (FSS).
Abstract: High-order bandpass frequency selective surfaces (FSSs) (N ≥ 1) can achieve high performance with a flat in-band frequency response and fast roll-off. One particular practical issue of designing bandpass FSSs using resonant surfaces is that the thickness of the substrate would be around a quarter of a wavelength. On the other hand, the size of a nonresonant FSS array element is usually large. A new miniaturized FSS capable of exhibiting a second-order bandpass response is proposed in this letter. Two miniaturized resonant surfaces coupled by a nonresonant inductive layer are used to build the proposed FSSs. An FSS operating at around 3.8 GHz is designed to verify the method. The element size is smaller than 0.076λ × 0.076λ for the proposed structure. This is significantly smaller than the element size of second-order FSSs designed using conventional approaches. The overall thickness is less than λ/24, where λ is the free-space wavelength at the resonant frequency. The method could be particularly useful for the design of FSSs at lower frequencies with longer wavelengths.

65 citations

Journal ArticleDOI
TL;DR: In this article, the capacitance and inductance of elementary periodic structures with capacitive and inductive surface impedances over a wide range of values are analyzed using three mechanical tuning techniques: overlapping combined with relative movement, stretching/compression, and flexure.
Abstract: We present techniques for designing large-scale, mechanically tunable periodic structures (PSs). Overlapping combined with relative movement, stretching/compression, and flexure are the three mechanical tuning techniques studied in this paper. We demonstrate that all of these mechanical movements may be used to tune the capacitance and inductance of elementary periodic structures with capacitive and inductive surface impedances over wide ranges of values. Analytic formulas for calculating the variable inductance and capacitance of these tunable PSs are also provided. These elementary PSs are the building blocks of a wide range of other PSs with more complicated unit cells and response types. One such structure—a frequency selective surface (FSS) composed of series combination of these inductive and capacitive structures—is also examined to demonstrate the application of the proposed tuning and analysis concepts. The FSS is fabricated on an accordion-like substrate that can be contracted or stretched to change its frequency of operation. The response and tuning properties of this structure are experimentally characterized using a free-space measurement system. A very good agreement between theory and experiment is obtained. This demonstrates that the behavior of such complex mechanically tunable PSs can be analyzed by examining the behavior of their constitutive inductive and capacitive elements.

30 citations

Journal ArticleDOI
TL;DR: In this paper, a new architecture for a miniaturized-element frequency selective surface (MEFSS) capable of providing a third-order bandpass response is presented and experimentally verified.
Abstract: A new architecture for a miniaturized-element frequency selective surface (MEFSS) capable of providing a third-order bandpass response is presented and experimentally verified. The proposed MEFSS consists of three metal layers separated from one another by two dielectric substrates. The exterior metal layers are nonresonant inductive wire grids, while the center layer is a hybrid resonator composed of an inductive wire and an I-shaped resonator. The exterior metal layers and the dielectric substrates act as two inductively coupled series resonators sandwiching the hybrid resonator layer in the middle. This results in a filter with a third-order bandpass response that can also provide an out-of-band transmission null at a frequency higher than that of the main passband. An equivalent-circuit-based synthesis procedure for this MEFSS is also presented in this letter that allows for designing the FSS from its desired system-level performance indicators (e.g., center frequency of operation, bandwidth, etc.). The validity of this design procedure is verified by presenting a design example and conducting full-wave electromagnetic simulations. Finally, an experimental proof-of-concept demonstration is performed by characterizing the unit cell of this MEFSS designed to operate in a WR-112 waveguide environment.

25 citations

Journal ArticleDOI
TL;DR: In this article, a millimeter-wave frequency selective surface (FSS) is presented for demultiplexing four atmospheric remote sensing bands with varying bandwidth (3-20 GHz) and frequency separation (50-195 GHz).
Abstract: A novel millimeter-wave frequency selective surface (FSS) is presented for demultiplexing four atmospheric remote sensing bands with varying bandwidth (3–20 GHz) and frequency separation (50–195 GHz). The unit cell (670 μm × 670 μm) is a circular metal mesh loaded with a monopole integrated concentric ring on a 175-μm-thick quartz substrate designed to reject 50–60 GHz (B1), 87–91 GHz (B 2), and 148–151 GHz (B3), and transmit 175–195 GHz (B4) for transverse electric (TE) and transverse magnetic (TM) polarizations at oblique incidence (25°−35 °). Transmission response of the cascaded FSS measured using a continuous-wave terahertz source showed insertion loss of 15 dB and higher in the reflection windows (B1, B2, and B3) and less than 0.5 dB in the transmission window (B4) for TE and TM polarizations at 30° incident angle.

12 citations

Proceedings ArticleDOI
01 Nov 2017
TL;DR: In this paper, a bandpass frequency selective surface (FSS) with a narrowband frequency response is presented, where the operation principle of the FSS is explained by using an equivalent circuit model where the passband bandwidth can be controlled by the values of the circuit elements corresponding to the geometrical dimensions of the unit cell.
Abstract: This article presents a bandpass frequency selective surface (FSS) with a narrowband frequency response. The designed FSS is made of miniaturized elements unit cell. The operation principle of the FSS is explained by using an equivalent circuit model, where the passband bandwidth can be controlled by the values of the circuit elements corresponding to the geometrical dimensions of the unit cell. The compatibility of the presented structure in designing higher order narrowband filtering responses is verified by designing a second-order bandpass FSS with 8.5% fractional bandwidth with a center frequency of 2.7 GHz.

4 citations