DIY Helix for 2.4 GHz uplink. Can I use 5mm copper tubing?

  • G0FYQ The square section boom does not affect the performance of the antennae at all. I have made a number of helical antenna using a aluminum boom without any problems. The one thing to be aware of is that you must not use strained wire for the helix: I did this on one of my helix antenna, and the results were very odd, the RF take off came at about 30 degrees from the axis of the boom. The quarter wave matching section is in fact the same as G3RUH's matching section but was easier to fabricate and mount. The antenna was tested at the AMSAT -UK test range with the following results

    Gain 14.8dbi
    Circularity 1 db

    Return Loss 19db


  • G8AWB thanks for that information it’s inspired me to go ahead and try building one.

    Question still open: are people still interested in such an article? Lots of DIY involved. nothing from shops except screws and N-connector.

    Return loss measured and exceeding 25dB (which is VSWR<1.12).

    @DH2VA Likewise, I would be interested in reading an article.

  • I according to the design of 26 N spiral antenna, the design gain for 23 db.Actual test can be generated in the cw mode than low noise and high signal-to-noise ratio of about 19 db.Now can work in digital communication mode.I think far not up to gain design.Who can give me a confirmation of parameters and drawings.thank you

  • BG0AUB I modelled and optimized 2.4 G helices since 2001 or so. Will change 'N' to 23 in my NEC file and get back to you here.

    Note that gains of helices are subject to debate and (iirc NRAO, American institute) determined/calculated that the gain of a helix is finite. Thus, it's not that doubling the amount of turns always yields +3 dB more.

    E.g. look at this article.