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.

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

Wave-transmitting materials are a kind of multi-functional materials that protect the normal operation of communication and guidance systems of spacecraft in harsh environments. In this paper, we fabricate a broadband microwave transparent Si3N4-SiO2 composite ceramic with excellent performance through digital light processing (DLP) 3D printing technology. The influences of sintering temperature on the weight increase rate, density, dimensional shrinkage, phase composition, microstructure, bending strength and dielectric properties of Si3N4-SiO2 ceramic were all systematically studied. The strength of Si3N4-SiO2 ceramic sintered at 1350 ℃ was 77 ± 5 MPa. The relative permittivity of the ceramic is within the range of less than 4, and the loss tangent can be below 0.003. The 3D printed Si3N4-SiO2 ceramic material exhibited excellent wave-transparent performance.

Preparation of broadband transparent Si3N4-SiO2 ceramics by digital light processing (DLP) 3D printing technology

High temperature ceramic radomes (HTCR) – A review

Ultra-low cost porous mullite ceramics with excellent dielectric properties and low thermal conductivity fabricated from kaolin for radome applications

In-situ mullite whisker reinforced aluminum chromium phosphate wave-transparent ceramics were designed and prepared The phase transformation, microstructure, mechanical and electrical properties of the ceramics were investigated, and the mechanisms of in-situ growth and toughening were discussed Results indicated that the in-situ growth of mullite whisker significantly improved the mechanical properties of the matrix, especially the high temperature flexural strength The room temperature flexural strength, 1000 °C flexural strength and fracture toughness of the ceramics were 13560 MPa, 12171 MPa and 452 MPa m1/2 After sintering at 1500 °C, the optimum properties of e'r, tanδ and microwave transmittance at region 8–12 GHz were 80%, respectively The sinterability of ACP matrix was improved by the in-situ process of high mullization above 1450 °C Using ACP binder as the raw material can avoid the phase transformation from B-AlPO4 to T-AlPO4 The synthesized mullite whiskers played a role in toughening by whiskers fracture, crack deflection and whisker pulling out

Preparation and properties of in-situ mullite whiskers reinforced aluminum chromium phosphate wave-transparent ceramics

Radome is an aerodynamic structural part attached to the fore-end of a missile. It transmits electromagnetic signals with minimum attenuation and also protects radar communication system, and thus, the radomes are made of ceramics as they have desirable properties required by the radomes. The flexural strength, dielectric constant, and loss tangent values of various ceramic materials used in the development of radomes are important in the selection of radome materials. Different nose cone shapes of missile radomes are also important. Ceramic materials show variational properties with sintering time, temperature, and other additives. The existing different near-net shape fabrication techniques for manufacturing of ceramic radomes are discussed and compared. Gelcasting is one of the manufacturing techniques to produce radomes with homogeneous and high green strength. Gelcast parts of silicon nitride ceramics are hard, tough, brittle, and wear-resistant and are difficult to machine using conventional methods of machining. Therefore, laser-assisted machining is used for fine finish of ceramic radomes with excellent surface integrity and productivity. This paper deals with a review of development of ceramic radomes, manufacturing methods for variety of applications.

Development of Silicon Nitride‐Based Ceramic Radomes — A Review

Fused silica ceramics with high flexural strength, and low warpage and shrinkage were casted using gelcasting, a near net shape fabrication technique. Methylacrylamide (MAM) and N,N-methylenebisac...

Surya Prakash Rao Chilakalapalli

Papers

Development of Silicon Nitride‐Based Ceramic Radomes — A Review

Effect of Monomers Content and their Ratio on Gelcasting of Fused Silica Ceramics