The WB3GCK Downspout Antenna Revisited

[A ham friend of mine recently asked me for the details of how I use my rain gutter and downspout as an antenna.  I originally did a write-up on it in 1994.  That article found its way into several ham radio publications and newsletters.  Most of the original article is still relevant but I have made some changes in the way I feed the “antenna.”  So, here’s an updated description of my Downspout Antenna. – WB3GCK]

After years of trying to come up with a good way to get on the HF bands from my little townhouse (without attracting a lot of attention from my neighbors), I started experimenting with using my aluminum rain gutter and downspout for an antenna. The results have been surprisingly good. In fact, it has turned out to be the ultimate low-profile antenna!

The downspout has a vertical run of about 16 feet, connecting the horizontal rain gutter which is about 16 feet long across the front of the house. Including the feed wire into the shack, the total length is in the neighborhood of 42 feet; over a quarter wavelength for 40 meters and almost a half-wave for 30 meters. The house is made of brick, so the entire system is isolated from ground.

Diagram of the WB3GCK Downspout Antenna
WB3GCK Downspout Antenna

I use my downspout like a random wire antenna, using a commercial autotuner (or internal tuner, in the case of my KX3). I feed the antenna through a homebrew 1:1 unun.  I use a short run of coax between the unun and the autotuner on my operating table.  A length of #22 stranded hookup wire is used to connect the output of the unun to the downspout outside.

To connect the wire to the downspout, I first sanded the downspout and connected the wire using three sheet metal screws.  I used multiple screws to help ensure a low resistance connection.  After making the connections to the downspout, I sealed them up using an adhesive/sealant called Goop.  Goop is available at most hardware stores.

With the downspout behaving essentially like an end-fed wire, it really helps to work this type of antenna against a good ground. Fortunately, my basement operating position is only a few feet away from where the water supply pipe enters the house. I used a piece of 1/2-inch copper pipe as a ground bus between my operating position and the incoming water pipe. A tinned copper braid strap and a couple of ordinary automotive hose clamps were used to connect the bus to the water pipe. A short braid strap connects the ground stud on the unun to the copper ground bus.

For good measure, I attached counterpoise wires to the ground stud of the unun; one each for 40, 30, 20, and 15 meters. The counterpoise wires are made from garden variety stranded hookup wire cut to a quarter-wavelength. I just run these wires around the shack, hiding them under the rug. Operation on the 80 meter band has been successful using just the ground bus.

How well does it work? During the first few months of operation, I worked 49 states; all with 5 watts or less. I’ve also worked a bunch of DX stations (though I’m more of a casual rag chewer than a DX-chaser). The length of the “antenna” is somewhat short for 80 meters, but performance on that band has been a big surprise. Signal reports on 30 and 40 meters, my primary bands, have been consistently good. In fact, the downspout has been my main antenna at home for more than 20 years.

While this arrangement has served me well, it is not without an issue or two.  I find that it helps to clean up and re-do the connections at the downspout periodically.  Typically, I do this maintenance every other year or so.  Also, I have noticed that my local noise levels on 80 and 40 meters have steadily increased over the years.  I attribute this to the proliferation of electronic gadgets both in my house as well as my neighbors’ houses.  Those bands are still usable, though.

Some words of caution are in order, however, if you plan to use your rainspout as an antenna:

  1. Make sure your gutter and downspout are isolated from ground.
  2. Make sure there is solid electrical continuity between the various sections of your downspout and gutter. Mine are fastened with pop rivets (not the greatest for RF work, but they appear to be doing the job.)
  3. Watch your power. I wouldn’t recommend running a kilowatt into your rainspout. Ham radio is fun, but not worth burning down your house.
  4. Make sure people and pets won’t come in contact with the “antenna” while you’re transmitting. This isn’t too much of a problem at QRP power levels, but be careful.

So, if you find your HF antenna options are limited by either space or legal restrictions, take a look at the outside of your house. There just might be a free multi-band antenna hanging out there!

72, Craig WB3GCK

 

4 thoughts on “The WB3GCK Downspout Antenna Revisited”

    1. Craig :

      I finally got around to trying this idea of using downspouts/rain-gutters as an antenna at home.

      I have a two story house that is about 25 feet across the back and about 50 feet long and my gutters form a horizontal U shape, with two downspouts at the back. So, assuming good electrical connections (hard to tell) I have something that looks like a T-antenna with the flat-top folded forward into a U and an extra vertical bit. I followed your advice of feeding it with a short length of coax to a 1:1 Unun and I am using 3 x 50 foot radials plus a ground rod and a connection to a cold water pipe (house plumbing is all copper). In a couple of hours of very casual operating in the ARRL 160m contest I worked 25 stations, most on the first call, with me running 5W! I don’t have space for a “real” 160m antenna so this gets me on that band. FWIW, I find it quite noisy on RX on the lower bands so I am using a Loop on the Ground as an RX-only antenna and the combo seems to be working pretty well for me on 160m QRP.

      For not a lot of effort, I am very pleased with the results. I can get a good match from 10m through 160m so now I have a backup antenna, in case my other antennas fall prey to ice storms over the winter (if the rain-gutters fall off the house I have bigger problems than antennas ;-o )

      Cheers

      Michael VE3WMB (Polar Bear #19) Grrrrr…

      P.S. I modeled this in EZNEC (purely speculative assuming all the aluminum is well bonded) and it shows that most of the current on 160m would be in the vertical downspout I am feeding, as well as the 25 foot horizontal run across the back of the house, making a 45 foot inverted-L. The two 50 foot horizontal runs along the side of the house seem to be acting mostly as loading on this band.

      Liked by 1 person

      1. Glad to hear your gutter antenna worked out for you. One of the major downsides for me is that it’s close to the house. As a result, I also have noise issues on the lower bands, with 40M being the worst. Good luck with your new “antenna.”

        72 & GRRR, Craig WB3GCK

        Like

      2. Craig :
        I too find it noisy on the low-bands, especially. I am using a TS-590SG at home and it has a separate RX antenna port that takes care of RX/TX antenna switching inside the rig. I laid down a LoG (Loop on the Ground) RX-only antenna in the backyard about a month ago and now don’t know how I ever lived without it.
        http://kk5jy.net/LoG/
        Our local club has an 80m SSB net on Sunday mornings and for the first time I am able to hear everyone checking in. On my 80m inverted-L, background noise tends to run from about S5 to S9+. The LoG gives me about a 5+ S-unit improvement in S/N, which makes a huge difference on 160m through 40m RX.
        Cheers
        Michael VE3WMB

        Like

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