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Hairpin matching for 20m 3-element Yagi - impedance transformation issues

Building a homebrew 3-element 20m Yagi based on the W6QHS design, but running into matching challenges. The natural impedance appears to be around 30-35 ohms, which should be easily matched with a hairpin, but lower impedance Yagis offer better performance. Currently seeing 2.8:1 SWR across the band with direct 50-ohm feed.

There are multiple ways to design a 3-element Yagi - equal spacing between all elements is the 'middle of the road' approach, but you can adjust spacing for wider bandwidth or higher gain. Boom length is 14 feet with 0.1λ spacing. Should I redesign element spacing or proceed with hairpin matching? Lower SWR is critical since even small misalignments can cause significant signal losses.

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  • John Taylor
    John Taylor

    What's your current driven element length and diameter? The 2.8:1 SWR suggests you're close but may need element tuning first. Element positioning has to be precisely maintained for proper impedance -

  • Emily Rodriguez
    Emily Rodriguez

    Been running W6QHS designs for years in contest setups. The hairpin is definitely the way to go, but consider the driver-to-director spacing adjustment for wider bandwidth if you're primarily working

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Stick with the hairpin match - it's the elegant solution here. Lower impedance Yagis around 30-35 ohms do offer better performance and are easily matched with a hairpin. Start with a hairpin length of about 6 inches, spaced 1 inch from the driven element center. Fine-tune by adjusting length and spacing. Much better approach than compromising the antenna design just to hit 50 ohms directly.

What's your current driven element length and diameter? The 2.8:1 SWR suggests you're close but may need element tuning first. Element positioning has to be precisely maintained for proper impedance - even small movements affect feedpoint impedance. I'd verify all dimensions against the original W6QHS specs before adding matching networks.

Been running W6QHS designs for years in contest setups. The hairpin is definitely the way to go, but consider the driver-to-director spacing adjustment for wider bandwidth if you're primarily working contests. You'll sacrifice maybe 0.5dB of peak gain but get much cleaner SWR across 14.000-14.350. For DXing, stick with the original spacing and hairpin match for maximum forward gain.

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