Saturday, September 2, 2017

Spiderfan 15m, 17m, 20m, 40m antenna, for 1/3 the price

I have been experimenting a lot with portable antennas.  This is an excellent. and EASY multi-band antenna for portable operation, or at your home QTH, provided you don't have very high noise.  You can build it for 1/3 the price of a buddy design, or just the cost of wire, if you have a tall tree.

This resonant 15m, 20m, 40m antenna, which also tunes to 6m, 10m, and 17m, will work DX on the high bands. It is best for short to medium distance on 40m (think most of USA), but will work out farther, if you are up high.

Perched halfway up a small mountain (240m above sea level), I contacted over 20 stations from my HL1ZIX QTH to the EU and the Middle East, in just a few hours.  I was running 90 watts, or less. Most DX stations were 3,000 to 5,000 miles away.  I also worked several contacts between 400 and 2,000 miles on 40m, as well as one contact out to 4,100 miles, in Oman.  Not bad!

Click to expand size
This antenna overcomes a typical problem.  If you have built a dipole, you have learned that it's easy to build an antenna that will work for 15 and 40m, but then you don't end up with a useable solution for 20m without having to resort to adding links (linked dipole), or coils.  Building coils can be a bit daunting for a new ham, and can be lossy.  Linked dipoles are great, but they require you to lower and attach or detach the links when you want to work the other band.

The "Buddy-based" antennas are of excellent build quality, but darned expensive, and they require set-up and change work between bands.  This antenna, which I called "Spiderfan" is both simple, easy to make, and extremely effective.  You don't have to get out of the chair to work all of the bands, once set up.  It does not compromise on any band, except about 1/2 s-unit on 17m, with DX still doable.  On 15m, 20m, and 40m, it is completely resonant and highly efficient!

This antenna is simple to build, because you just need to cut the wires to provided lengths.  The 20m portion should be spot-on.  It's also adjustable by folding ends of wires, but it should be close.  I love this antenna, because I don't need a tuner on 15m, 20m, or 40m, and I can also work 17m with a tuner.  If I want to change bands, I just flip a switch.  No lowering the antenna to tap coils to change bands!  The really nice addition is that 20m is vertically-polarized, so I can work more DX there.  You can also experiment with the 40m legs, adding a lot more wire, and unrolling it for 80m, if you care to work NVIS from that band.

To build this antenna, you will need:

1.  About 32 meters (105 feet) of wire 14awg or 16awg recommended.
2.  An inexpensive 1:1 balun at the feedpoint (not necessary, but highly recommended)
3.  A 12m (40ft) Spiderbeam HD fiberglass pole, or a tree at least that high
4.  Some thin rope for tying the ends of the 40m legs
5.  Some electrical tape, for taping wire to the pole

Here is a video of a contact from Korea to Australia (over 5,000 miles) on a different outing, using this same antenna:


  1. Great!!.Congrats,will try this,I just bought an Spiderbeam 18m.
    Kind regards from Transylvania.
    73&DX's Val,YO6DDF.

  2. If the 1:1 balun is "unnecessary," why not feed the 40-meter dipole with 450 ohm, or 600 ohm feed line from the tuner.
    -Greg K3ANG

  3. Hi, First I apologize if my comment doubles. It seems Google removed integration with Blogger. You can give ladder line a try, but I have a feeling you'll be best off using an antenna analyzer to determine what balun is best. I could be wrong. I have never tried ladder line on a multi-element antenna, like this.