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ABSTRACT A novel superstrate‐based Vivaldi antenna design characterized by high‐gain and wideband performance is presented. The proposed design configuration features a Vivaldi antenna positioned between high dielectric superstrate (Rogers 6010, εr = 10.2) with copper etched off on both sides and an FR4 substrate that has copper etched on one side only. The introduction of a high permittivity dielectric material above and a reflector below the Vivaldi antenna enables favorable resonance conditions for achieving high‐gain operation. The measured antenna exhibits a peak gain of 17 dBi at 10 GHz, covering an operating frequency range of 6–20 GHz. It also features a narrow half‐power beamwidth and low side lobe level radiation patterns. Unlike existing studies, which rely on metamaterials, electromagnetic bandgap structures, and frequency selective surfaces for gain enhancement, our design employs high‐dielectric constant superstrates. This approach increased the antenna's peak gain by 10 dB. Also, the proposed configuration act as a radome protecting the antenna from Environment. [ABSTRACT FROM AUTHOR]

Copyright of Chinese Journal of Computational Mechanics / Jisuan Lixue Xuebao is the property of Chinese Journal of Computational Mechanics Editorial Office, Dalian University of Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Antenna design and optimization must ensure robust electrical performance, making its analysis a crucial step in all antenna design processes. Traditionally, this analysis involves setting up various cases after establishing the calculation model, comparing the performance of each case, and summarizing the impact of relevant factors to guide design and optimization. However, this method is time-consuming and inefficient. This paper proposes a sensitivity-based approach for analyzing antenna electrical performance, using a radome-covered array antenna as an example. First, we derive the formulas for calculating the antenna's electrical performance and its sensitivity to the current amplitude, array element position, and radome thickness. We then design comparative experiments to analyze the antenna's performance using the sensitivity-based method and the traditional case enumeration method. Comparing the conclusions of both methods, we find that they yield the same results regarding antenna performance. The proposed sensitivity-based method offers a quantitative evaluation of various influencing factors and provides a more scientific and systematic approach to analyzing antenna electrical performance. [ABSTRACT FROM AUTHOR]

In this paper, a broadband reconfigurable active frequency selective rasorber is proposed, which can be used as a radome for antenna radar cross section (RCS) reduction. By tuning the active components, the radome can achieve in‐band RCS reduction and reconfigurable absorptive/transmissive states. In the absorptive state, the max bandwidth with an absorption rate greater than 90% spanning from 1.62 to 5.37 GHz; in the absorptive/transmissive state, 2.2 GHz is the transmissive frequency with the insertion loss of 93% while absorbing in 0.94–2.06 GHz and 2.63–6.5 GHz, which demonstrate impressive characteristics of broadband and a high absorption rate. Additionally, the radome can maintain performance at ±35° angular incidence and is insensitive to incident wave polarization. Furthermore, it features a lightweight and low‐profile design, with a cell electrical size of just 0.078λ × 0.078λ × 0.066λ. The prototype test shows a noteworthy correlation with simulation. This study has wider applications in the electromagnetic stealth of communication antennas and aircraft, as well as in the control of electromagnetic pollution signals in space. [ABSTRACT FROM AUTHOR]

This paper presents a full-wave method, based on the method of moments (MoM), to calculate the S ¯ matrix from a two-dimensional complex sample in millimeter and submillimeter W and J bands. From the surface currents obtained by inverting the impedance matrix and from the Huygens principle, the reflection and transmission coefficients are computed. This allows us to obtain the four elements of the S ¯ matrix. Firstly, the method is validated from canonical samples (a dielectric slab and a stack of two dielectric slabs) by applying the well-known Fresnel coefficients. Secondly, for the W (75 to 110 GHz) and J (220 to 330 GHz) bands, a PVC slab covered by water drops is considered, for which the S ¯ matrix is compared with measurements made in quasi-optical free space. A satisfactory agreement is obtained between the measurements and the model. [ABSTRACT FROM AUTHOR]

Rainfall can reduce the radar signal through a radome. The effects of different water layers on the radome transmission are studied using quasi-optical measurement from 26 to 330 GHz including water permittivity characterization. The water is deposited as drops of different sizes or as a uniform layer while keeping a constant volume, highlighting the importance of the control of the total wet surface for radar applications. A compact model is proposed to predict the signal loss due to water on the radome depending on the rain flow. [ABSTRACT FROM AUTHOR]

A novel frequency selective surface (FSS)-based spatial bandpass filter for TM-polarized waves is reported. The unit cell of the proposed FSS consists of a dielectric substrate with two conducting layers on opposite sides. One magnetic resonator is placed on the top conducting layer, while two pairs of electric resonators are positioned on the bottom conducting layer to provide a fast roll-off bandpass characteristic. The simulated values of the −3 dB to −10 dB roll-off factor (RF) for the proposed structure are 140 and 280 dB/GHz on the lower and upper sides of its passband, respectively. To validate the simulation results of the proposed structure, a prototype of the FSS-based filter was fabricated and tested experimentally. Furthermore, the present simulation results are benchmarked with the band-pass FSSs reported in the literature, demonstrating an advantage of the proposed filter over the filters mentioned in previous works. [ABSTRACT FROM AUTHOR]

Metasurface radome is crucial to protect the radiating antenna and control electromagnetic waves flexibly. However, current design methods for metasurface radome merely focus on the single propagation direction, with limited degrees of freedom. Here, a super radome is proposed with a directional scattering response based on Janus metasurface that can realize the phase modulation of y‐polarized waves and the amplitude modulation of x‐polarized waves with a judiciously designed structure. Both numerical and experimental results illustrate two cross‐polarized transmission windows with intensity exceeding 0.9 centered at 10 and 12.2 GHz and two out‐of‐band invisibility with considerable backward radar cross‐section reduction over −10 dB within 9.3–15.4 and 7.5–23.8 GHz when the radome is illuminated by y‐ and x‐polarized waves along negative and positive z directions, respectively. Moreover, the radar cross‐section reduction is maintained for off‐normal incidence even up to 45°. This method sets up a directional degree of freedom for advanced radome design and demonstrates its enormous potential in developing next‐generation stealth antennas. [ABSTRACT FROM AUTHOR]

This paper presents a high-performance dual-band radome composed of cyanate/quartz fiber composite and frequency-selective surfaces (FSS). The practical steps from FSS and radome segmented design to fabrication are presented. The transmission characteristics of the FSS plate and radome are measured using the free-space method, and the results show that the FSS achieves transmission in both Ku and Ka bands, with frequency points of 15.4 GHz in the Ku band and 33.8 GHz in the Ka band, which confirms the feasibility of the FSS and radome segmented design. After that, the electrical performance of the radome is measured. The results show that the power transmission coefficient of the radome is not less than 70% in the range of ± 40°, and the maximum value of the center frequency is greater than 85% in the Ku/Ka operating band under vertical and horizontal polarization. The boresight error (BSE) is less than 20.5′ within ± 20° of the scanning angle. These results confirm that this FSS structure has high value for application in a curved radome. [ABSTRACT FROM AUTHOR]

This paper presents a waveguide Lens antenna at the W-band adopting dual-focusing Lens to improve the performance. The Lens antenna consisted of a waveguide slotted structure and lenses processed using NOA73 meet the demands of miniaturization for current communication systems. The antenna radome fabricated using NOA73 not only protects the antenna structure but also improves the gain of the antenna by about 9.5 dBi via electromagnetic wave dual-focusing. A prototype is fabricated using novel UV-LIGA technology. Measured results are compared with simulated values. Measured results confirmed the fabricated antenna operated in the W-band with a 10 dB fractional bandwidth (FBW) of 6.5% from 97.5 to 104 GHz and a peak gain of 22 dBi at 100 GHz in the direction perpendicular to the plane of the feed waveguide. A good agreement between simulation and measurement is obtained, demonstrating efficient radiations in the operating band. [ABSTRACT FROM AUTHOR]

How to arrange a periodic array consisting of precise unit-cells on a complex surface has always been a difficulty affecting the application of frequency selective structures. Based on the elastic deformation theory of thin-shell, a perfect mapping between a curved surface and a planar array by using the weighted minimum distortion flat-unfolding solution of the surface is established and then extended to the 3-Dimensional (3D) case along the thickness direction. With the help of this mapping, the information of the unit-cell can be mapped to the thick surface structure while maintaining the topological properties of the planar periodic array and the internal structure of the unit-cell. In the mapping process, the deformation of the unit-cell on the thick surface structure relative to the original unit-cell can be evaluated, and this deformation has local adjustability. This manuscript provides a class of local unit-cell deformation control algorithms that do not affect the completeness of the mapping. The application effect and potential of this method are demonstrated by an example of a spliced conical radome using a three-layer hybrid unit-cell.

The open-source code PSSFSS for analysis and design of polarization selective surfaces (PSSs), and frequency selective surfaces (FSSs) is presented, beginning with an introduction to the Julia programming language in which the code is written. Analysis methods and algorithms used in PSSFSS are described, highlighting features of Julia that make it attractive for developing this type of application. Usage examples illustrate the code's ease of use, speed, and accuracy. [ABSTRACT FROM AUTHOR]

This work proposes a frequency‐selective surface‐based radome structure to selectively allow the radar altimeter operating band and also minimize the interference from Sub‐6GHz 5 G frequency bands. A Jerusalem cross and combinational loop (JCL) based frequency selective surfaces (FSS) unit cell of overall dimension 0.37λ was synthesized using a thin flexible substrate for use in fuselage of airborne systems. The proposed FSS unit cell exhibits transmission zero at 3.61 and 6.025 GHz and highly selective pass band at 4.3 GHz. The effect of bends and angle of incidence on the frequency response of the synthesized FSS was studied in transverse electric and transverse magnetic modes. A lumped element‐based equivalent circuit model for the proposed design was also presented. Finally, the fabricated prototype was experimentally validated in an Anechoic chamber setup and the suitability of the proposed FSS layers for aviation radar systems was confirmed. [ABSTRACT FROM AUTHOR]

Automatic protection of EM detecting systems from unexpected high-power incidence is important to the robustness and life of a passive detecting system. In this paper, an adaptive metamaterial radome which automatically shields the receiving antenna from strong incident wave is designed. Based on standard wire medium, PIN diodes are added between adjacent wires. When the incident EM wave is weak, the diodes are in "off" state and affect little to the transmission of the wire medium. When the incident EM wave is strong enough to turn the diodes to "on" state, electric currents will be automatically formed in the diodes and the power transmitted to the antenna will be largely reduced. The adaptive transmission of the proposed radome is validated by the simulation and measurement results. [ABSTRACT FROM AUTHOR]

In this paper, an in-band and out-of-band microwave wireless power-transmission characteristic analysis of a slot ring radome based on an approximate analytical method is proposed. The main contribution of this paper is that, in the approximate analysis of the ring radome, a unified expression of the incident field on the radome surface is derived with E-plane and H-plane scanning, and the ring is approximated as 30 segments of straight strips. Solving the corresponding 60 × 60 linear equations yields the electric current distribution along the ring strip. The magnetic current along the complementary slot ring is obtained by duality. Thanks to the fully analytical format of the current distribution, the microwave wireless power-transmission characteristics are efficiently calculated using Munk’s scheme. An example of a slot ring biplanar symmetric hybrid radome is used to verify the accuracy and efficiency of the proposed scheme. The central processing unit (CPU) time is about 690 s using Ansys HFSS software versus 2.82 s for the proposed method.

The radome is an important component of the aircraft seeker. The radome of high-speed aircraft usually has ablation, which affects the electromagnetic performance of the radome. Therefore, it is important to study the electromagnetic performance of the radome wall during high-temperature ablation. However, most existing studies mainly consider the influence of temperature and ignore structural changes caused by ablation. To solve the above problems, this paper studies the influence of ablation on the electromagnetic performance of inhomogeneous radome walls (IRW) by considering the structure parameters, thermal expansion characteristics, and dielectric parameters during the ablation. The two typical types of IRW design methods are analyzed, the parameters calculation method in the ablation process is proposed, and the influence of ablation on the two types of IRW is studied. The results give the electromagnetic changing characteristics of the IRW under different ablation conditions. The contribution of this work is to lay a solid theoretical foundation for improving the performance of the radome in the ablation process, which is of great significance. [ABSTRACT FROM AUTHOR]

This research paper presents constitutive parameters of toxic marine invaders (Diadema setosum) and offers the availability of materials from these invaders for microwave applications. Two different powder form of these invaders were prepared and calcined at different temperatures. These biomaterials have been obtained for grinding shell and spines of sea urchin were turned into powder. The constitutive parameters as complex dielectric constants of these classified biomaterials have been investigated in 3.2- 20 GHz frequency range with open-ended coaxial probe method. Measured results show that these biomaterials have a potential usage area in microwave range are mentioned firstly in literature. Measured complex permittivity properties of samples of shell and spines of invasive long-spined sea urchin have demonstrated that samples can be utilized in development of high-quality microwave radomes with high impedance matching to air and low loss microwave substrates. [ABSTRACT FROM AUTHOR]

5G antennas typically operate in outdoor environments. These outdoor factors can reduce antenna accuracy, shorten life, and cause poor operational reliability. Therefore, applying materials with water-repellent properties to the radome can play an important role in protecting them from external environments. This paper reports a superhydrophobic nanocoating that can be sprayed on the radome. The dielectric constant of the coating is 2.709, and the dielectric strength is 38.58 kV/mm. The radome with a superhydrophobic coating was tested by rain, and its signal transmission is only −0.24 dB. Meanwhile, the static contact angle of the coating can reach 157°. [ABSTRACT FROM AUTHOR]

SiO2‐Al2O3‐CaO‐based glass (10–60 wt%)/mullite composites were investigated for the LTCC and radome applications. The optimum densification temperatures decreased from 1550°C (10 wt% glass) to 1400°C (30 wt% glass) by means of liquid‐phase sintering, and to 850°C–825°C (50–60 wt% glass) by means of viscous phase sintering. XRD analysis showed that mullite was the main phase as well as in situ crystallized anorthite after 825°C. The composite with 20 wt% glass was a suitable candidate for the radome applications (bulk density = 2.86 g/cm3 after sintering at 1450°C, dielectric constant (loss) = 7.12 (0.0025) at 5 MHz, thermal expansion coefficient = 4.27 ppm/°C between 25°C and 800°C, thermal shock resistance parameter = 162°C), and the composite with 50 wt% glass was a suitable candidate for the low‐temperature cofired ceramic applications (bulk density = 2.64 g/cm3 after sintering at 850°C, dielectric constant (loss) = 6.79 (0.0043) at 5 MHz, thermal conductivity = 2.11 W/m⋅K at 25°C, and thermal expansion coefficient = 3.93 ppm/°C between 25°C and 300°C). [ABSTRACT FROM AUTHOR]

In order to explore the impact of metal oxide diverter strip layout on radome lightning protection, the breakdown characteristics of metal oxide diverter strip were studied in this manuscript through a high voltage test. The effect of different lengths and numbers of metal oxide diverter strips and antenna deflection on the electric field in a radome was studied by carrying out a lightning protection design test on a certain radome and electrostatic field model simulation analysis. The results show that the breakdown voltage of the metal oxide diverter strip is proportional to the voltage change rate. The electric field intensity around the antenna gradually decreases with the increase of the length and number of metal oxide diverter strips. The electric field intensity around the antenna is reduced from 1. 35 MV / m to below 0. 5 MV / m by optimizing the diverter strip layout, which meets the lightning protection requirements. The problem of antenna radome perforation caused by the excessively induced electric field is solved by this method, which is of great significance to the lightning protection design of the radome and its internal antenna equipment. [ABSTRACT FROM AUTHOR]

2D woven composites can be used in the manufacture of Radomes due to the abilities of low cost, flexible properties, formability and structural stability. By analyzing fabrics structures, a wave-transparent model was established based on surface equations of fabrics and surface deformation principle. Glass fibers were woven into plain fabrics with different parameters and covered on the surface of ellipsoid Radome model, then the woven composites were cured with epoxy resin. The validity of the proposed model was verified by an experiment with the free space method in a range of 1-18GHz. The results showed that the transmission efficiencies of composites were greater than 90% and had great relation with fibers volume content. It explains the mathematical relationship between fabrics structure and transmission efficiencies. [ABSTRACT FROM AUTHOR]

This paper presents the design and fabrication of a wideband array antenna module for a two-dimensional (2-D) interferometer direction-finding system. The array antenna module comprises an installation panel, spiral antennas, absorbers, and a radome. The absorber was configured to minimize the phase difference between vertical and horizontal polarizations to reduce the degradation of the direction-finding performance. Rubber and foam absorbers were applied in a hybrid form to minimize diffuse reflection. The radome was applied using an A-sandwich structure and manufacturing a laminated structure with a small vertical- and horizontal-polarization phase difference. The average phase difference between the vertical and horizontal polarizations of the array antenna was measured as an azimuth of 8.09° and elevation of 7.89°. Therefore, the fabricated array antenna can be applied to the 2-D interferometer direction-finding system. [ABSTRACT FROM AUTHOR]

In this paper, we introduce a 3-D printed lattice core for wide-angle scanning radome operating in the X-band. We explain the fundamental design methodology of the sandwich structure for radome and outline the technique to represent the 3-D printed core in terms of its effective dielectric constant. Our study further delve into the electrical characteristics of the unit cell, focusing on its performance with varying incident angles within the X-band. Utilizing 3-D printing technology, we fabricate the sandwich structure and measure its transmittance through the free-space measurement method. Our designed structure achieve a transmittance exceeding 77% for incident angles up to 45 degrees. We fabricate and measure six distinct samples, and the compiled data is present in a table. The findings highlight the high electrical performance of the sandwich structure and demonstrate its suitability for X-band wide-angle scanning applications.

In this paper, we propose a novel algorithm to compute the radiation pattern of a slot array antenna covered with frequency selective surfaces (FSS) based on ray tracing technique. We observe that the proposed algorithm can greatly reduce computational resources while yielding accurate numerical solutions, compared to cases using standard full-wave and conventional high-frequency approaches. The underlying principle is to combine the image method and physical optics technique. More specifically, the proposed algorithm (i) employs a boundary box that encloses the slot array antenna with FSS to correct phase errors and then (ii) calculates equivalent surface currents flowing on the boundary box. The surface of the boundary box is discretized by regular grids (or boundary meshes) and a ray path reaching each square cell in the boundary meshes is determined based on the image method. After collecting all the rays hitting the boundary meshes, equivalent surface current densities can be computed for the resulting radiation pattern. The proposed algorithm is suited best for dealing with electrically large structures much more efficiently and can advance the existing design process.

Copyright of Electroplating & Finishing is the property of Electroplating & Finishing Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Quartz fiber is an ultra-high purity silica glass having immediate use applications on radomes and satellite communications for aerospace systems. In this study, the uses of quartz fiber as an antenna radome and a dielectric substrate were investigated for a patch antenna designed to operate at f=8 GHz. In order to compare the performance of quartz fiber as an antenna radome, glass fiber is examined for the same antenna. For the dielectric substrate case, quartz fiber is compared with the well-known and widely used dielectric substrate of FR-4. The electromagnetic properties of the quartz fiber were examined for different temperature values using a free space measurement setup and a controllable furnace. The antenna parameters, including radiation pattern, gain, return loss and beamwidth, are investigated and compared in detail for all cases in order to demonstrate the effects of using quartz fiber as a radome and an antenna substrate. The results highlight that quartz fiber shall have highend use for low electromagnetic interference characteristics without compromising on structural integrity. [ABSTRACT FROM AUTHOR]

Powder Metallurgy (P/M) involving Cold Isostatic Pressing (CIP) and Hot Isostatic Pressing (HIP) techniques is the best suited processing route for manufacture of critical components from ceramics and highly complex metallic materials. The CIP followed by sintering route was adopted for the development of fused silica radomes for application in high-speed target seeking missiles. On the other hand, the HIP, a single-step processing technique has been used for the development of First-Wall (FW) of Test Blanket Modules (TBMs) from India Specific Reduced Activation Ferritic Martensitic (INRAFM) steel. The FW is an important component required for International Thermo-nuclear Experimental Reactor (ITER) application. The details of innovative processes which have been established to overcome the specific technical challenges for the development of CIP and HIP technologies for manufacture of silica radomes and INRAFM steel first-wall respectively for intended applications are highlighted in this paper. [ABSTRACT FROM AUTHOR]

Uncertainty is widely present in composite structures, and the probabilistic model is one of the most common ways to describe uncertainty. In some engineering problems, incomplete knowledge leads to uncertainty in the distribution parameters of probabilistic models. In this paper, the uncertainty of the distribution parameters is described by intervals, and the uncertainty analysis of a radome made by honeycomb sandwich composite is performed under imprecise probability. To reduce computational costs, a back propagation analysis neural network (BPA-NN) based on data from finite element analysis (FEA) is constructed. A variance-based global sensitivity analysis (GSA) is conducted to identify input variables that have a large influence on the output characteristics of the composite structure. A buckling failure model is established to evaluate the safety of the composite structure, and then GSA based on failure probability is carried out to identify input variables that have a large influence on the failure probability of the structure. The uncertainty analysis under imprecise probability in this paper provides a framework for the reliability assessment and design of composites. [ABSTRACT FROM AUTHOR]

This paper presents a waveguide Lens antenna at the W-band adopting dual-focusing Lens to improve the performance. The Lens antenna consisted of a waveguide slotted structure and lenses processed using NOA73 meet the demands of miniaturization for current communication systems. The antenna radome fabricated using NOA73 not only protects the antenna structure but also improves the gain of the antenna by about 9.5 dBi via electromagnetic wave dual-focusing. A prototype is fabricated using novel UV-LIGA technology. Measured results are compared with simulated values. Measured results confirmed the fabricated antenna operated in the W-band with a 10 dB fractional bandwidth (FBW) of 6.5% from 97.5 to 104 GHz and a peak gain of 22 dBi at 100 GHz in the direction perpendicular to the plane of the feed waveguide. A good agreement between simulation and measurement is obtained, demonstrating efficient radiations in the operating band.

Design / Build / Fly (DBF) is an annual and international remote controlled aircraft design competition that provides engineering students an opportunity to develop an aircraft that meets the competition requirements set by AIAA. This year’s competition requires teams to develop a short takeoff, carrier based aircraft with remotely folding wings and capable of carrying and releasing cargo. After analyzing the score analysis, our team determined that the highest scoring potential is to maximize the amount of stores carried while completing an equal number of laps within a 10 minute window. The team explored a wide range of options and finalized on an aircraft design that meets the given constraints while also excelling in mission performance. Our aircraft consists of a 75 in wingspan, an aspect ratio of 6.25, a maximum takeoff weight of 16 lbs, and a cargo capacity of 12 stores. Faculty Advisors: Professor Robert H. Liebeck; Advisors: Colin Sledge, Joseph Hsieh, Paul ParcelContact DBF Team • Nathan Yeung nhyeung@uci.edu • Marlon Sevilla marlonps@uci.edu • Brian Chen brianlc1@uci.eduEmail: dbf.uci.sdp@gmail.com Facebook: https://www.facebook.com/dbfuci/ For more information, visit: http://www.aiaadbf.org/

This paper investigates the low-RCS Ka-band receiving and transmitting satellite communication antennas co-designed with the high-performance absorbent frequency-selective radomes (AFSR). Consisting of the metamaterial absorber (MA) upper layer and bandpass FSS lower layer, two AFSRs operating at 19 and 29 GHz (receiving and transmitting central frequency) with low-frequency wideband absorbing and high-frequency low-insertion-loss transmission performances are proposed. To meet the needs of Ka-band satellite communication, two 4 × 4 microstrip array antennas working at the same central frequencies are co-designed with the AFSRs. We demonstrate the effectiveness of the proposed AFSRs and co-designed antenna through simulations and measurements. The results show that the gain degradations are only 0.44 dB and 0.58 dB at two central frequencies after loading the AFSRs separately, and 10-dB RCS reduction bandwidths are ranging from 6.1–16.3 GHz (relative bandwidth 91.1%) and 10.2–24.8 GHz (relative bandwidth 83.4%) individually. [ABSTRACT FROM AUTHOR]

In this study, dual-band frequency selective surface (FSS) structures are designed by using 3-D printing technology for antenna radome applications. Four different configurations are studied to find the best alternative for FSS substrate not only for electromagnetic (EM) responses but also for its mechanical properties suitable for radomes. To ease the manufacturing process, a conductive paint is also studied instead of copper microstrip lines. In addition, graphite is also used for the comparison. Different 3-D printed configurations, various thickness values and three different materials for conductive part are examined and compared to find the most efficient radome structure. [ABSTRACT FROM AUTHOR]

The radome is an important component of the aircraft seeker. The radome of high-speed aircraft usually has ablation, which affects the electromagnetic performance of the radome. Therefore, it is important to study the electromagnetic performance of the radome wall during high-temperature ablation. However, most existing studies mainly consider the influence of temperature and ignore structural changes caused by ablation. To solve the above problems, this paper studies the influence of ablation on the electromagnetic performance of inhomogeneous radome walls (IRW) by considering the structure parameters, thermal expansion characteristics, and dielectric parameters during the ablation. The two typical types of IRW design methods are analyzed, the parameters calculation method in the ablation process is proposed, and the influence of ablation on the two types of IRW is studied. The results give the electromagnetic changing characteristics of the IRW under different ablation conditions. The contribution of this work is to lay a solid theoretical foundation for improving the performance of the radome in the ablation process, which is of great significance.

The use of fifth-generation (5G) new radio (NR) spectrum around 26 GHz is currently raising the quest on its compatibility with the well-established Earth exploration-satellite service, which may be blinded by the spurious radiation emitted above the horizon (AtH) by base station (BS) antennas. Indeed, AtH grating lobes are often present during cell scanning due to the large interelement spacing in BS array antennas for achieving higher gains with a reduced number of RF chains. In this letter, we propose an approach based on an electrically thin metasurface-based dome for the reduction of AtH grating lobes in 5G-NR BS antennas. The proposed scanning range shifting approach exploits the natural lower amplitude of the grating lobes when the antenna array scans in an angular region closer to the broadside direction. The grating lobe reduction is here demonstrated considering a 1×4 phased linear antenna array operating under dual-liner ±45°-slant polarization. A simple design procedure for designing the metasurface dome is reported, together with the antenna performances, evaluated through a proper set of numerical experiments. It is shown that the grating lobe radiation toward the satellite region is significantly reduced, whereas the overall insertion loss is moderate. [ABSTRACT FROM AUTHOR]

In this letter, a Jaumann-like rasorber is examined, which offers wideband absorption, angular stability, and polarization insensitivity. The structure is defined by three layers with two resistive layers placed on top of a lossless layer. Also, all three layers use capacitors to ensure compactness for the metasurface rasorber. These features provide broad angular stability up to 55 $^{\circ }$ while also maintaining low insertion losses of about 1 dB and only 0.6 dB for measured broadside incidence. The rasorber is also shown to work as a radome in the near field of a planar antenna array. [ABSTRACT FROM AUTHOR]

In this paper, we present a linear to circular polarization converter integrated in a concrete structure to eliminate signal transmission problem originated from the concrete buildings in microwave regime. Two polarization converter samples and a control specimen made by traditional concrete are designed and their signal transmission responses are compared experimentally. Axial ratio values which can be calculated by the ratio between the co-polar transmission and cross-polar transmission results of the proposed samples are below 3 dB and highly sufficient for linear to circular polarization conversion activity. The operating frequency for the proposed sample 1 is between 6 and 6.5 GHz with 500 MHz of bandwidth. The proposed sample 2 exhibits dual-band operation covering frequency bands, 4.58–5.13 and 6.0–6.4 GHz with bandwidths of 550 and 400 MHz, respectively. Operating frequencies of the samples are in the WIMAX frequency bands. In addition, the liner to circular polarization converter design integrated to concrete has a huge potential to improve reflection and directivity parameters of many antennas if it is considered as a radome. [ABSTRACT FROM AUTHOR]

Based on the method of moments, the interpolative decomposition (ID) technique is extended to accelerate the evaluation of radome boresight error (BSE) and transmissivity, which belongs to electromagnetic radiation problems with the right-hand side (RHS) matrix containing multiple vectors. Because the RHS matrix from radiation problems has many null rows, the matrix can be first reduced to a compressed form, then decomposed by the ID technique to figure out the skeleton RHS vectors by exploiting its rank-deficient property. Iterative solutions are only executed for these skeleton vectors, followed by the restoration process to obtain the full solutions. Compared with the existing ID methods designed for scattering problems, the proposed ID method is much easier to implement and companied with a high solution efficiency. Numerical experiments are performed on an antenna array enclosed by a radome to evaluate the BSE and transmissivity, illustrating the performance and accuracy of the proposed method. [ABSTRACT FROM AUTHOR]