Building a Cobweb Antenna and Testing it with NanoVNA [with video] 12

AWK Cobweb antenna parts

AWK Cobweb antenna parts

Recently I decided to take down my Western HF-10 multi band dipole, actually scrap that, a fox did the work for me and chewed through the kevlar guy ropes supporting it. They saved me a job really – just in a slightly less elegant way!

I’d contemplated a Cobweb antenna for some time, they have near the efficiency of a multi-band fan dipole, but seem to have some magic quality, which means you can get a good low angle takeoff, without having the antenna far off the ground. How this works, I don’t know – maybe something to do with the arrangement of the elements?

The finished Cobweb in the air

The finished Cobweb in the air

It’s essentially a multi-band fan dipole, but wrapped around fiberglass spreaders in a square arrangement, this means I can have access to 7 bands (20m, 17m, 15m, 12m, 10m, 6m and even 4m), with only a width of 2.7m on each side. It’s also omni-directional, which saves the hassle of a rotator.

I investigated building a Cobweb antenna, but eventually decided on buying one for £200 from AWK Antennas, a Polish amateur on eBay. The metal wrangling was the bit I have neither the tools or the skills for!

Here’s the video of putting it together and testing it with the NanoVNA:

So far I’ve had it for one week and I’ve worked Alaska, West Coast U.S, Mauritania, Lebanon and Saudi Arabia for all time new ones. It definitely works better for long distance DX than the Western HF-10 it replaced! The build quality seems really good and it’s really performing just 5m above ground.

NanoVNA sweeping the 17m band

NanoVNA sweeping the 17m band

12 thoughts on “Building a Cobweb Antenna and Testing it with NanoVNA [with video]

  1. Pingback: Upgrading my HF Base Station ← M0JCQ's Ham Blog

  2. Reply Me Nov 22,2020 15:36

    Hello…been watching the cobweb video, and looks very small and nice for a small garden, my question is, will it load up on 40 m…7.030 with a ATU. if so how does it perform if you have tried it….Martin.G0MVP

    mjisted@btinternet.com

    • Reply James Stevens Nov 29,2020 07:53

      Hi Martin,

      I have not tried this yet, but as I don’t have anything up for 40m I may well give it a go!

      73 James M0JCQ

  3. Reply mark corristine Dec 11,2020 01:25

    did it come with the mast?
    great video by the way
    mark M7RKN

  4. Reply mark corristine Dec 17,2020 02:06

    Hi mark again mine came today . and only 12 and 15 will tune on my 7300 .the rest are well over 3:1 .i got a nano 2 just waiting for some 239 to sma’s . im brand new to all this. Any tips . although im sure its all in your great video . regards mark M7RKN

    • Reply James Stevens Dec 18,2020 14:52

      Hi Mark,

      That’s strange, all the specified bands should be within 3:1. How high up do you have Cobweb? Is there anything else nearby which might be interacting with it?

      Once you get the Nano VNA on it you’ll be able to see the real resonant points for the lower bands. I’d expect it to be narrow on some bands, so you might want to tune that element according to your preference (CW/SSB/Data).

      73 James M0JCQ

      • Reply John Laidler May 11,2021 15:12

        James, that cobweb antenna looks very suitable for my small garden. Does it need an earth below the mast or does the coax come straight back to the radio which is the only bit earthed? The reason for asking is most of my garden is rocky and creating an earth is difficult.

        • Reply James Stevens Jun 7,2021 16:31

          Hi John,

          It doesn’t need an earth, the coax comes straight back to the radio.

          73 James M0JCQ

  5. Reply mark corristine Dec 18,2020 17:44

    Hi yeah i have it in the loft . and the measurements provided (only for 20m) would mean i’ll have to cut some off the ends if i want it to appear like it says . im reluctant to do that . still waiting for bloody plugs ! Arrghh

    • Reply James Stevens Dec 22,2020 11:31

      It’s possible there could be something near in the loft which is detuning it.

      You can try bringing in the resonance by simply folding back the ends (instead of cutting them), this is a good and less permanent way of tuning. It’s easy to trim, but hard to reattach 😉

      73 James M0JCQ

  6. Reply Mike G3ZCC Apr 23,2021 03:11

    Hi Martin
    Do you know what the gain is?
    May have to put one up to be compliant for emf
    73 Mike G3ZCC

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