Frequency Selective Surface Radome Research Articles

Broadband low radar cross section frequency selective surface radome based on phase cancellation and spatial filtering

AbstractThis letter introduces a novel design approach for broadband radar cross section (RCS) reduction of frequency selective surface (FSS) radomes. The approach integrates the principles of phase cancellation and spatial filtering together through a hybrid design method. The phase cancellation is obtained through the checkerboard arrangement of units, and the spatial filtering characteristics is achieved by the slot etched on the ground plane. Experimental and simulation results demonstrate that etching slots on the ground plane maintains broadband in‐phase reflection and bandpass characteristics, thereby extending the bandwidth of RCS reduction through a combination of two operation bands. Theoretical analysis of the working mechanism is also provided using equivalent circuit models. In comparison to the conventional radomes, the proposed FSS radome achieves significant bandwidth improvement for RCS reduction, indicating that it has promising prospects in future low‐RCS radome applications.

A Rapid Modeling Method for Airborne FSS Radomes Based on Dynamic Customizable Primitives

The digital model of airborne frequency selective surface radomes (AFSSRs) is the basis of design, simulation analysis, manufacturing, and other related research on AFSSRs. This paper proposes a rapid modeling method for AFSSRs based on dynamic customizable primitives. Firstly, a layered digital model construction scheme for AFSSRs is presented based on the typical radome wall structure. Then, according to the characteristics of various surface configurations and the complex wireframe information of AFSSRs, the dynamic primitives are raised to express the boundary and contour information of all kinds of radomes. Focusing on the undevelopable characteristics of the aerodynamic shape surface of the AFSSR, the arrangement solution and mapping method for frequency-selective elements on undevelopable surfaces are proposed. Furthermore, the implementation logic of this method for the creation of each layer model and the assembly of the whole machine model is introduced. Finally, a rapid modeling system (RMS) is established based on this method, enabling the automated creation of digital models of AFSSRs. Utilizing this system resulted in modeling time savings ranging from 20% to 97.5% compared to traditional methods, which verifies the feasibility and effectiveness of this method.

Design and Characterization of the Fully Metallic Gap Waveguide-Based Frequency Selective Radome for Millimeter Wave Fixed Beam Array Antenna

This article presents a bandpass frequency selective surface (FSS) radome based on fully metallic gap waveguide (GW) technology. The element of the proposed FSS radome consists of a conventional cross-dipole slot etched on metallic plates and positioned over a groove GW cavity. A design with a single GW-cavity layer was initially produced which was later optimized for performance, to comprise a dual GW-cavity layer, while considering both functionality and manufacturability. It is shown that the proposed FSS element offers a stable and wide bandpass (from 26 to 30 GHz) performance in the broadside direction for both transverse electric (TE) and transverse magnetic (TM) polarizations. For oblique angle of incidence, the suggested FSS element works up to 30° with a reduction in usable bandpass bandwidth performance to 26–28 GHz for both TE and TM polarizations. A <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$20 \times 20$ </tex-math></inline-formula> -element GW-FSS array prototype has been fabricated and measured, which was integrated with a fixed-beam array antenna to further validate its functionality as a filtering radome. The findings show an excellent agreement between simulations and measurements. Hence, the proposed GW-FSS represents a great opportunity to develop an all-metallic FSS with low insertion loss, sharp-roll-off filtering, wideband performance, and inexpensive fabrication cost.

Analysis of Radome Cross Section of an Aircraft Equipped With a FSS Radome

We study the radar cross section (RCS) property of an aircraft considering the electromagnetic (EM) characteristics of a frequency selective surface (FSS) radome, mounted on the aircraft. Instead of full-wave methods, we utilize high-frequency methods, such as the shooting and bouncing rays (SBR), physical theory of diffraction (PTD), and flat model, taking a significant computational efficiency. Based on the developed algorithm, we analyze monostatic and bistatic RCSs of the aircraft equipped with either single- and multi-layer dielectric, FSS, or PEC radomes in terms of frequency and polarization. Our calculations are validated by comparing with those of the commercial EM simulator with significant computational efficiency. The present numerical study indicates that including the radome EM characteristics into the overall aircraft RCS study is crucial for the accurate RCS estimate

Analysis of Transmission Loss and Boresight Error of a Curved FSS Radome-Enclosed Antenna

In this paper, we numerically study a curved frequency selective surface (FSS) radome, which encloses a waveguide slot array antenna operating at 10GHz, using the ray tracing technique and flat model. The transmission loss (TL) and boresight error (BSE) are calculated for various degrees of freedom, such as elevation and azimuth angular scanning or gimbal systems of array antennas to examine the electromagnetic properties of the curved FSS radome. Our calculations of radiation patterns, TL, and BSE for a multi-layered dielectric radome are compared with those of a commercial EM solver for validation. Importantly, we quantify phase distortions, incurred by the curved FSS radome, using the insertion phase delay (IPD) of transmitted fields on the radome surface. Thereby, we demonstrate that the BSEs strongly depend on (1) the spatial distribution of phase distortions on the radome surface and (2) their average level. The present method is highly suited for analyzing radomes with arbitrary surface patterns inserted.

Additive Manufacturing of Conformal Microstrip Antenna Using Piezoelectric Nozzle Array

Inkjet printing technology is widely used in the manufacture of conformal structures, such as load-bearing antennas or frequency-selective surface radomes. It is particularly promising for preparing conductive patterns on non-developable surfaces. Existing printing technologies employ a single nozzle and a five-axis linkage technique for printing, which is time-consuming. In this study, a conformal plane printing technology based on the arrayed nozzle was developed to prepare conductive patterns on a non-developable surface. The technique actualizes fast printing of passive circuits on a conformal surface, such as a microstrip antenna. Compared to printing techniques employing a single nozzle, the proposed method greatly improves the printing efficiency on conformal surfaces. Specifically, we first developed a model for the driver waveforms and the printing injection parameters via simulation. Subsequently, the accuracy of the computational fluid dynamic simulation results was validated by comparing them with the experimental measurements of droplet trajectory captured using a camera. Next, a droplet spreading model was established, considering energy conservation principles. Finally, a conformal surface printing technology using arrayed nozzles was developed based on the injection parameter and droplet spreading models. The effectiveness and feasibility of the proposed printing method were further validated via simulation and experimental tests of return loss.

EM Design and Analysis of Frequency Selective Surface Based on Substrate-Integrated Waveguide Technology for Airborne Radome Application

In this paper, a bandpass frequency selective surface (FSS) based on substrate-integrated waveguide (SIW) technology is presented for airborne radome application. The proposed FSS element consists of a tapered cross-slot on either side of the substrate surrounded by metallic vias. The structure selectively allows the impinging electromagnetic (EM) wave through it in the specified frequency band. The element shows very stable frequency response for oblique incidence and the sharp roll-off performance characteristics at the edges of operating region in the rejection band. The −10 dB relative bandwidth (BW) of the element is 12.8% from 9.5 to 10.8 GHz with a very good insertion loss (IL) of 0.1 dB. Furthermore, the spectacular advantages of the FSS element based on SIW have been used for modeling the airborne radome application. The proposed radome structure is operating at 10 GHz with a relative 10 dB BW of 25.0% (8.20–10.6 GHz) with maximum (IL) better than 0.1 dB in its passband. The behavior of the FSS radome has been analyzed at different conformal sectors and thickness is optimized for optimal performance. The key parameters of radome such as transmission performance, radiation efficiency, and radar cross section (RCS) have been studied. Experimental verifications are carried out to prove the validity of the estimated results. The results show promising performance of the proposed FSS based on SIW technology for airborne radome application.

Design and development of angularly stable and polarisation rotating FSS radome based on substrate‐integrated waveguide technology

In this paper, the design of a novel polarisation rotating frequency selective surface (FSS) radome is presented based on substrate integrated waveguide (SIW) technology. The proposed radome consists of an FSS core with Y-shaped slots on either side of the substrate and surrounded by metallic vias. The primary function of the core is to select the linear polarisation from the impinging electromagnetic (EM) wave and to rotate the wave into 90° clockwise direction in the X-band regime. The radome structure shows a relative bandwidth of 13.2% from 9.2 GHz to 10.5 GHz with impedance matching better than -10 dB and the insertion loss (IL) better than 0.5 dB. The proposed structure shows very stable resonance performance with sharp band edge characteristics compared to the existing FSS radomes. Also, the conformal analysis of the proposed structure has been carried out to study its behaviour for real-time radome applications. Finally, to prove the efficacy of the proposed structure, a prototype has fabricated and measured its performance in a free space measurement setup. A good agreement is observed between the experimental and simulated results. Furthermore, the conversion of E -field pattern to H -field pattern and vice-versa is proved from the experimental verification.

Radiation from a Cavity-Backed Circular Aperture Array Antenna Enclosed by an FSS Radome

Radiation from a cavity-backed circular aperture array antenna enclosed by a frequency selective surface (FSS) radome is studied using the hybrid analysis method, by combining the mode matching method, the ray tracing technique, and Huygens’s principle. The equivalent magnetic surface currents on the apertures are derived from the aperture electromagnetic fields, which are calculated based on the mode matching method. The rays are generated from the equivalent magnetic surface currents and used to analyze the FSS radome based on the ray tracing technique. After being obtained from both the mode matching method and the ray tracing technique, electromagnetic fields on an outermost radome are transformed into the equivalent electric and magnetic surface currents using Huygens’s principle. The radiated fields are computed from the equivalent surface currents and compared with the measured data.

Design and Verification of an Integrated Free-Standing Thick-Screen FSS Radome

Frequency selective surface (FSS) radomes can effectively improve the stealth of flying weapons. In this letter, an integrated free-standing thick-screen FSS radome is designed using the CST simulation software. The bandpass characteristic is achieved by Y-shaped apertures with periodic distribution around the central axis of the radome. Based on a model of a round-head FSS radome with a built-in phased array antenna, we have analyzed the bandpass transmittance and boresight error of the radome. The copper shell was prepared by a spin forming process. The FSS radome was fabricated by a laser robot system with multiple degrees of freedom and a rotary platform. The results of the microwave anechoic chamber test show that the thick-screen bandpass FSS radome has a good electromagnetic performance with a passband transmittance of about 80% and a stopband transmittance of less than 10%.

一体化曲面共形频率选择表面雷达罩

一体化曲面共形频率选择表面雷达罩

Design of FSS radome using binary particle swarm algorithm combined with pixel-overlap technique

An optimization method for designing frequency selective surface (FSS) radome using binary particle swarm optimization (BPSO) algorithm combined with pixel-overlap technique is proposed, in this paper. The proposed method takes the connectivity condition of adjacent conductors within FSS element into consideration. With the help of pixel-overlap technique, lattice points in FSS element are avoided by overlapping adjacent conductors, which improves the manufacturability of the FSS layers. Also, structure parameters of the FSS radome can be obtained according to the desired frequency selective property using the BPSO algorithm. To verify the validity of the proposed method, a sandwich-structured FSS radome is designed, fabricated, and measured. Good agreements between the simulation and measurement results can be observed, which demonstrate that the proposed method can be applied to design FSS radome.

Modified silica ceramic for frequency selective surface radome

Modified silica ceramic for frequency selective surface radome

Analysis of FSS Radomes Based on Physical Optics Method and Ray Tracing Technique

In this letter, we analyze the electromagnetic characteristic of a frequency selective surface (FSS) radome using the physical optics (PO) method and ray tracing technique. We consider the cross-loop slot FSS and the tangent-ogive radome. Radiation pattern of the FSS radome is computed to illustrate the electromagnetic transmission characteristic.

Status and development of frequency selective surface radome

Due to the working characteristics of radar system, i.e. it has to ensure the emission and acceptance of its own radar wave, frequency selective surface (FSS) radome is the most effective stealthy way to give radome the function of frequency-selective. Combining the FSS technique and the radome together, FSS radome provides bandpass transmission properties in the operating frequency of radar, and changes the RCS characteristics of the antenna compartment when it is beyond the antennas operating frequency range, thus it is a realization of out-of-band stealth. This paper introduces the basic design of FSS radome technology and summarizes the research status of FSS radome in the structure design and the technology. The muti-band FSS radome, intelligent FSS radome, thick-screen FSS radome, miniaturized element FSS radome and the technologies to construct radome are predicted to be the perspective of FSS radome.

유한크기 FSS의 곡률효과에 따른 주파수 특성 해석

In this paper, we have analyzed the curvature effects of the finite FSS(frequency selective surface) using the 3-D method of moment using the BiCGSTab algorithm as an iterative method. To validate the analysis method in this paper, we compared the RCS(radar cross section) of PEC(perfect electric conductor) sphere with theoretical results and it shows well agreements. The tripole slot FSSs which have many application in military were selected for the investigation of curvature effect and RCS as a frequency characteristics were observed with the variation of the curvature rate. Simulation results shows that curvature effect can significant effect the passband frequency and bandwidth of FSS. We suggest that the curvature effect must be considered at the stage of design FSS application like FSS radome.

Filter-Antenna Consisting of Conical FSS Radome and Monopole Antenna

A filter-antenna consisting of a monopole antenna and a conical frequency selective surface (FSS) radome was designed and investigated. A coupled-resonator spatial filter (CRSF) was used to design an FSS array with stable performances, and then a specific geometrical layout was proposed to construct a conical FSS radome. We technically investigated the combination of a monopole antenna and the conical FSS radome. Both the simulated and measured results show that the proposed filter-antenna keeps the input reflection coefficient, radiation pattern of the monopole antenna within the designed passband, and reflects out-of-band signals. Such properties of the filter-antenna will exhibit anti-interference capability and low RCS, which can be widely used in military applications.

Simple design method of FSS radome analysis using equivalent circuit model

We propose a simple design method for the Frequency Selective Surface (FSS) radome using an equivalent circuit model. Using a transmission and reflection method, the material properties, such as the permittivity and permeability of the FSS, were extracted from an FSS equivalent circuit model. Also, we propose a design equation for the resonant frequency of FSS radome due to the dielectric cover effect. The material properties of the FSS with dielectric covers were obtained and can be used to calculate the transmission characteristics of FSS radome. To validate the proposed method, the FSS radome is fabricated and the results of transmission characteristic are compared to the proposed method in this paper. The results were strongly positive. The method proposed herein can be used for the simple design and fabrication of an FSS radome and can be applied to the analysis of FSS radome for use with various communication systems and electrical instruments.

Simple prediction of FSS radome transmission characteristics using an FSS equivalent circuit model

We propose a simple method for predicting the characteristics of Frequency Selective Surface (FSS) radome using an equivalent circuit model. The required material properties, such as the permittivity and permeability of the FSS, were extracted from a FSS equivalent circuit model using a transmission and reflection method. These parameters were then used to calculate the transmission characteristics of FSS radome. We designed a sandwich radome using a square loop FSS for a 23GHz band application. In order to demonstrate the validity of our approach, we also performed a simulation to obtain the characteristics of the FSS radome using commercial full-wave software. The results from the two approaches are in good agreement. The method proposed herein could be used for the simple and rapid calculation of the design and fabrication of a FSS radome. The FSS radome is that a square loop FSS that has a stop band at 23GHz is insulated between two dielectric materials. A simple analysis of a FSS radome requires the material constants, the permittivity and permeability of the square loop FSS, which we extracted using transmission/reflection. Using the material constants derived from a FSS equivalent circuit model, the characteristics of the FSS radome were calculated for a simple 2-D case. The results were verified using a commercial full-wave three-dimensional electromagnetic wave simulator. The resulting characteristics of the FSS radome agreed with those obtained using a full-wave simulation. We show herein that the characteristics of a FSS radome can be analyzed and predicted with relative ease using an approximate FSS to achieve a simple 2-D construction. Our method can be applied to the analysis of FSS radome for use with various communication systems and electrical instruments.

A novel miniaturized frequency selective surface with excellent center frequency stability

AbstractA novel miniaturized frequency selective surface is proposed. The size reduction is achieved by bending the edge of square loop aperture into the inner space to lengthen the resonant length. Compared with conventional square loop aperture frequency selective surface (FSS), the area of this miniaturized‐element is reduced by 78% at the same operation frequency of 2.9 GHz. Both theoretical and experimental investigations are carried out. It is observed that the miniaturized FSS presents excellent center frequency stability with the increase of the incident angle. This proposed FSS can be a good candidate for FSS radomes which present large incident angle to the coming wave. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 2513–2516, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24604