Rainspout Antenna


From: Craig LaBarge (74740.3166@compuserve.com)
Date: Wed Nov 09 1994 - 17:23:50 EST


The following article is being posted in response to some questions
regarding the antenna I use for QRP. This might be of some interest
to those with antenna restrictions or limitations.


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!

I use my downspout like a random wire antenna, using a commercial
transmatch. A piece of #22 stranded hookup wire runs from the transmatch
to the downspout and is attached with a sheet metal screw. The downspout
has a vertical run of approximately 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.

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 transmatch to the copper ground bus.

For good measure, I attached counterpoise wires to the ground stud of
the transmatch; 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 44 states; all with 5 watts or less. I've also worked a
handful 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 now become my main antenna.

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

4. Make sure people and pets won't come in contact with the
"antenna" while your 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!

                    73 DE CRAIG WB3GCK

Search QRP-L Archives

[ QRP-L Archive | ]
[ 1993 | 1994 | 1995 | 1996 | 1997 | 1998 | 1999 | 2000 ]


This archive was generated by hypermail 2b29 on Fri Jun 02 2000 - 11:27:08 EDT