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In a Yagi-Uda antenna using aluminum tubing, does the wall thickness of the hollow elements have a measurable effect on the antenna’s Q-factor and operating bandwidth?

 I'm building a high-performance Yagi for 432 MHz using 12mm OD aluminum tubes. I can choose between 1mm and 2mm wall thickness. The heavier, thicker tube is stronger, but does it offer any RF performance advantage? At UHF, the skin depth is shallow (~4 μm). Since current flows on the outer surface, does a thicker wall reduce resistance by providing a "smoother" bulk material path, or is the RF resistance essentially set by the outer circumference and surface roughness alone? Could a thicker wall slightly lower losses and thus the system Q, yielding a tiny bandwidth increase?

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By Ruchika Tuli Answered 1 year ago

At 432 MHz, skin depth is ~4 μm, so the RF current is confined to a thin layer on the outer surface. Whether the wall is 1mm or 2mm thick, the effective conducting cross-section is identical—it's essentially a cylindrical shell of thickness ~3-5 skin depths. Therefore, wall thickness has negligible direct impact on RF resistance or Q-factor. The dominant loss factors are surface roughness and joint conductivity. A thicker wall may offer indirect benefits: it's less prone to deformation, maintaining consistent element shape, and can be machined for smoother joints. However, for pure RF performance, choose the thinnest wall that meets your mechanical strength and weight requirements. Focus on ensuring clean, tight electrical connections at element mounts, as this is where significant loss can occur.

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