Telescopic antenna sleeve
The telescopic antenna sleeve is the outer protective casing of telescopic antennas used in devices such as radios, walkie-talkies, and car radios. Typically made of insulating or metal materials, it supports the antenna rod, provides insulation, and provides decorative aesthetics. Lengths typically range from 100-500mm , diameters from 5-20mm , and wall thicknesses from 0.5-2mm . The material selection depends on functional requirements. Insulating sleeves are commonly made of engineering plastics such as ABS and PVC , while metal sleeves are typically made of H62 brass or 1060 aluminum. ABS plastic sleeves are most widely used in civilian equipment due to their excellent insulation (volume resistivity ≥ 10¹⁴Ω・cm ) and low cost.
The manufacturing process for telescopic antenna sleeves varies depending on the material. Plastic sleeves are extruded using an extruder. ABS resin pellets are heated to a temperature of 200-230°C in a melted state and then extruded through a die into a tubular shape at a speed of 10-20 m/min. The cooling water tank temperature is controlled at 20-30°C to ensure dimensional stability, with an outer diameter tolerance of ±0.1mm and a straightness of ≤1mm/m. Metal sleeves are drawn using H62 brass strip. The sleeves are first rolled into a tubular shape and welded together. The sleeves are then cold-drawn through multiple passes, reducing the diameter by 15%-25% per pass. After drawing, they are annealed (at 300-350°C for 1 hour) to relieve stress, and finally electroplated (nickel or chromium) with a thickness of 5-10μm to enhance wear resistance and aesthetics. Regardless of the material, both ends of the sleeves are chamfered (at an angle of 30°-45°) to remove burrs and ensure smooth telescopic movement of the telescopic rod.
The performance advantages of the telescopic antenna sleeve enable it to meet the special working requirements of the antenna. First, it offers excellent insulation performance. The plastic sleeve has a breakdown voltage of ≥20kV/mm, effectively isolating the antenna rod from the device housing to prevent signal interference and electric shock risks. Second, it offers good mechanical properties. The ABS sleeve has a tensile strength of ≥40MPa, making it difficult to break, while the metal sleeve has a hardness of ≥HV80, capable of withstanding the friction caused by frequent extension and retraction of the rod. Third, it offers excellent weather resistance. The plastic sleeve exhibits no cracking or deformation in temperatures between -40°C and 80°C, while the metal sleeve, after electroplating, offers salt spray resistance for ≥48 hours, making it suitable for outdoor use. Fourth, it offers a low coefficient of friction. The inner wall roughness is Ra ≤1.6μm, and the friction coefficient with the antenna rod is ≤0.3, ensuring smooth extension and retraction with a service life of ≥100,000 cycles. Fifth, it offers lightweight properties. The plastic sleeve has a specific gravity of 1.05-1.15g/cm³, while the metal sleeve reduces weight by 30% through its thin-wall design (wall thickness ≤1mm), in line with the trend towards miniaturization of equipment.
In various application scenarios, telescopic antenna sleeves are essential components for various radio devices. Portable radios use ABS plastic sleeves with a diameter of 5-8mm and a length of 100-200mm, featuring decorative patterns on the surface, ensuring both functionality and aesthetics. Walkie-talkies use metal sleeves (H62 nickel-plated brass) with a diameter of 8-12mm and a length of 200-300mm, offering enhanced drop resistance and adaptability to harsh outdoor environments. In vehicle-mounted radios, telescopic antenna sleeves are made of PVC with a diameter of 12-15mm and internal reinforcement ribs for improved structural stability. Aviation walkie-talkies utilize 1060 aluminum sleeves with an anodized surface for lightweighting, resulting in a 40% reduction in weight compared to brass sleeves. In traditional televisions, outdoor antenna sleeves use ABS sleeves with a diameter of 15-20mm, with color-coded sleeves to distinguish between different frequency bands.
Industry trends indicate that telescopic antenna casings are moving towards multifunctionality, lightweighting, and integration. The use of multifunctional composite casings (e.g., inner insulation + outer metal shielding) ensures insulation while reducing electromagnetic interference. The use of nano-modified plastics increases casing strength by 20% while reducing weight by 10%. Integrated design integrates the casing and antenna base into a single mold, reducing assembly steps. Intelligent production, utilizing precision extrusion dies and in-line dimensional inspection, maintains product tolerances within ±0.05mm. The use of environmentally friendly materials, including biodegradable plastics and chromium-free electroplating processes, reduces environmental impact. While wireless communication technology will reduce reliance on telescopic antennas in the future, high-performance telescopic antenna casings will continue to innovate to meet specialized needs in specific areas (such as emergency communications and shortwave radio).
