Copper and copper alloy waveguides
Copper and copper alloy waveguides are hollow metal conduits used to transmit electromagnetic waves, including microwaves and millimeter waves. They offer low loss, high power capacity, and excellent shielding properties, making them indispensable in radar, communications, satellites, and electronic countermeasures. Their primary materials are oxygen-free copper (TU1, TU2), phosphorus-deoxidized copper (TP1, TP2), and brass (H62, H65). Oxygen-free copper waveguides have a conductivity of ≥98% IACS and an electromagnetic wave transmission loss of ≤0.1dB/m, making them suitable for high-precision radar systems. Phosphorus-deoxidized copper waveguides offer excellent weldability and can be formed into complex shapes, making them suitable for communications equipment. Brass waveguides offer lower cost and higher strength, making them suitable for applications requiring less precise precision. Waveguides come in a variety of cross-sectional shapes, including rectangular, circular, and elliptical. Rectangular waveguides are the most widely used, with common sizes ranging from 10mm×20mm to 50mm×100mm. Their inner surface finish should have an Ra of ≤0.8μm to minimize electromagnetic wave reflection losses.
The production process for copper and copper alloy waveguides is complex, requiring multiple high-precision steps including forming, welding, and precision machining. For rectangular waveguides, sheet metal bending is typically used: 0.5-2mm thick oxygen-free copper sheets are repeatedly bent into rectangular cross-sections using a CNC bending machine, with a bending angle tolerance of ≤0.5° to ensure cross-sectional verticality and symmetry. For circular or complex-section waveguides, extrusion or stretching is used. After heating the copper billet to 300-500°C, it is extruded through a die into a tubular shape and then stretched to correct dimensions. Welding is performed using argon arc welding or electron beam welding, with weld strength ≥200MPa. The inner wall welds must be polished to Ra ≤1.6μm to prevent electromagnetic wave reflection at the weld. The finished waveguide tube needs to be precisely processed, with the port flatness ≤0.01mm and the perpendicularity to the flange ≤0.05mm/m. Finally, it must pass the air tightness test (pressure ≥0.3MPa without leakage) and microwave transmission performance test (standing wave ratio ≤1.1) to ensure product quality.
In radar systems, copper and copper alloy waveguides are core components for signal transmission, directly impacting radar detection accuracy and range. Long-range early warning radars utilize TU1 oxygen-free copper rectangular waveguides with a cross-sectional dimension of 30mm x 60mm. These waveguides are capable of transmitting X-band (8-12GHz) electromagnetic waves with a transmission loss of ≤0.08dB/m, increasing the detection range of one early warning radar by 10%. Due to limited space, shipborne radars utilize special-shaped waveguides (such as L- and T-shaped ones). Precision welding enables signal transmission over complex paths, reducing the size of a destroyer’s radar system by 25%. Weather radar waveguides are made of corrosion-resistant brass, ensuring stable operation in harsh outdoor environments. This has reduced the failure rate of radar equipment at one weather station by 35%.
The communications and satellite industries place stringent performance requirements on copper and copper alloy waveguides. Satellite communication ground station feeder systems utilize TP1 phosphorus-deoxidized copper waveguides to transmit high-frequency signals in the Ka -band ( 26.5-40 GHz ). A standing wave ratio (SWR) of ≤ 1.05 ensures stable signal transmission, reducing the bit error rate (BER) at one satellite ground station to below 10⁻⁹ . 5G millimeter-wave base stations utilize miniaturized waveguides ( 10mm×20mm cross-section ) for signal transmission, capable of supporting high-power (≥ 100W ) signals. This has increased the coverage of one 5G base station by 20% . Broadcast and television transmission tower feeders utilize brass waveguides, connected via flanges to form transmission lines hundreds of meters long. This has resulted in a 5% increase in signal transmission efficiency for one television station .
As microwave technology advances toward higher frequencies and wider bandwidths, copper and copper alloy waveguides are experiencing continuous breakthroughs in performance. Manufacturers have developed waveguides with gold-plated inner walls, with a gold layer thickness of 0.5-1μm, which reduces transmission loss by 30%, making them suitable for deep-space exploration radars. For high-temperature environments, copper alloy waveguides (such as Cu-Cr-Zr alloy) have been developed, maintaining stable transmission performance at 150°C and suitable for aircraft engine radars. In terms of process innovation, 3D printing technology is being used to manufacture complex waveguides, shortening development cycles. For a military enterprise, the development cycle for a new radar waveguide was reduced by 60%. In the future, with the advancement of technologies such as 6G communications and space exploration, demand for high-performance copper and copper alloy waveguides will continue to grow, driving the development of materials and processes towards higher precision and lower loss.
