Attenuator coaxial structure optimization design focuses on refining the geometric and material configuration of the coaxial assembly (inner conductor, outer conductor, dielectric, resistive element) to maximize performance, minimize size, and enhance manufacturability—addressing the limitations of traditional coaxial structures (e.g., poor heat dissipation, large size, frequency-dependent losses) in modern RF systems. Unlike incremental design changes, structural optimization involves a holistic redesign to align with specific application needs, such as miniaturization for portable test equipment or high-power handling for radar systems.

The core structural optimization directions include: 1) Conductor Structure Design: - Inner Conductor Optimization: Use a hollow inner conductor (instead of solid) for weight reduction (30% lighter) and improved heat dissipation (via internal air flow). For example, a 1.0 mm outer diameter hollow inner conductor (0.5 mm inner diameter) maintains the same impedance as a solid 1.0 mm conductor but reduces thermal resistance by 20%, ideal for portable attenuators. - Outer Conductor Innovation: Design the outer conductor with a split-sleeve structure for easy assembly and disassembly, while maintaining mechanical rigidity. The split-sleeve uses a precision-machined aluminum alloy with a tongue-and-groove joint, ensuring electrical continuity (resistance <5 mΩ) and impedance consistency (±0.5Ω) across the joint. This structure reduces assembly time by 40% compared to seamless outer conductors. 2) Dielectric Material & Configuration: - Low-Loss Dielectric Selection: For high-frequency applications (>20 GHz), use liquid crystal polymer (LCP) dielectric (dielectric loss tangent 0.002 at 20 GHz) instead of PTFE (0.0002 at 1 GHz, but 0.001 at 20 GHz). This reduces insertion loss from 0.3 dB/m to 0.1 dB/m at 30 GHz, critical for satellite communications where signal loss must be minimized. - Dielectric Support Optimization: Replace solid dielectric with a spiral-wound dielectric support (e.g., PTFE tape) to reduce dielectric volume by 60%, lowering capacitance and improving high-frequency performance. A 20 dB attenuator with a spiral dielectric support achieves 1.05:1 VSWR at 40 GHz, compared to 1.2:1 with a solid dielectric. 3) Resistive Element Integration: - Embedded Resistive Element Design: Embed the thin-film resistive element directly into the dielectric material (e.g., ceramic) using laser ablation, eliminating the need for a separate substrate. This reduces the attenuator’s axial length by 30% (from 50 mm to 35 mm for a 20 dB model) and improves thermal conductivity by 50%, as heat transfers directly to the dielectric and outer conductor. - 3D Resistive Network: For high-attenuation values (>60 dB), use a 3D resistive network (instead of planar) to reduce size and improve frequency response. A 60 dB 3D π-type network (stacked vertically) occupies 40% less volume than a planar network, making it suitable for miniaturized test equipment.

A defense contractor reported that a structurally optimized coaxial attenuator (hollow inner conductor, LCP dielectric, embedded resistive element) met radar system requirements for high power (100 W), wide frequency range (1-18 GHz), and small size (40 mm × 15 mm × 10 mm), replacing a larger traditional model that failed to fit in the radar’s compact housing. Structural optimization should be validated via mechanical testing (e.g., vibration, shock) and electrical testing to ensure both performance and durability.

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