Put a Scrap Satellite Dish to Good Use
If you do any kind of
live sports event coverage, check out this project from Newman-Kees’
Frank Hertel. It doesn’t cost much, doesn’t take a lot of time
(less than an hour) and results in a parabolic microphone that will
give your sports remotes some outstanding field or court noise.
Fig. 1: There’s a new
use for these old satellite dishes.
Fig. 2: First, remove
the feed horn and electronics assembly.
First you need to locate
the scrap dish, such as the one pictured in Fig. 1. Along with the
dish, you’ll need some pieces of 1/2-inch copper pipe and a couple
of 1/2-inch fittings.
Comments accompany each
picture here but you can also use your imagination. As presented, the
parabolic microphone works well; however, you may think of a way to
improve it. A deeper dish will offer a more directional pickup
pattern, but almost any dish will work. For this project, Frank used
an omnidirectional microphone. A directional or cardioid mic may or
may not be an improvement. Try it and see.
So with the dish cleaned
and in hand, let’s begin. The first step, shown in Fig. 2, is to
remove the dish feed horn assembly and electronics module. Save the
circular support ring, seen in Fig. 3, as it will be used as a
template for fabricating a filler plate for the hole where the feed
horn assembly was mounted.
Using a piece of scrap
aluminum, trace the support ring and cut it out, as show in Fig. 4.
In Fig. 5, you can see how the rough-cut filler is sanded to provide
the finished hole-cover.
Bolt the filler into
place, using four #6x32 bolts, washers and nuts, shown in Fig. 6.
At this point, the work to
manufacture the microphone support begins. As seen in Fig. 7, cut a
1-1/4 inch piece of half inch copper pipe. Securing the copper tube
in a vise, serrate one end down to the depth of the hack saw blade.
Fig. 3: Save the metal
Fig. 4: Use the ring to
trace a filler panel carefully.
Next, shove the serrated
end into a mic adaptor, as shown in Fig. 8. This will initially shape
it to size. After removing the copper tube from the mic adaptor, it
will look like the piece pictured in Fig. 9.
Fig. 10 demonstrates how
to slightly bend the serrated ends, which will secure the microphone
And now, to assemble.
Frank found that for this size dish, the piece of copper pipe is
about 9 inches long. This shallow dish has a broad focus. As seen in
Fig. 11, mount a 90-degree sweat (ear) mount to the dish. Insert the
9-inch copper tube and connect a 45-degree sweat elbow to the other
end of the tube. To the other end of the 45-degree coupling, insert
the mic adaptor you just modified.
Fig. 12 shows the
finished product, with the mic adaptor added and the microphone in
position for testing.
Though you would think
that the copper joints could be soldered, Frank suggests securing
them with #6x3/8 self-tapping screws. This will provide for easy
assembly or reassembly, making physical changes for different
microphones possible. Although the serrated mic holder adaptor holds
the threaded mic adaptor well, Frank suggests you epoxy that
assembly, which will keep the mic from rotating off axis.
Frank was going to remove
the tubular support ring system, but found that it’s an easy way to
hold and point the parabolic microphone, and also serves as a good
protective support when laying the dish down. Frank adds that there
is ample room behind the dish to add a battery-powered microphone
preamp, limiter and even a headphone monitor for the operator.
Fig. 5: Cut, shape and
smooth the filler panel.
Fig. 6: Fasten the
filler panel to the dish, using four #6x32 bolts and nuts.
Frank ends his project by
offering one other construction tip. To cancel handling noise or
ambient noise, you can parallel a second omnidirectional mic. Mount
this second mic to the top of the dish and wire it out of phase.
Tying the two mics together, common noise will be canceled. The
parabolic mic will be the only mic to “hear” the sound at which
it is pointed. This is an old theater/sound reinforcement trick, and
it works quite well.
If you build one of these,
take some high-resolution pictures and send them to me — especially
if you make modifications.
Get a guy or gal from the
track team to run up and down the court, aiming the parabolic at the
players, then mix that live action with your sportscasters. Sporting
events will really come alive.
Fig. 7: Serrate an edge
of the copper support pipe.
Fig: 8: Shove the
serrated pipe into the microphone adaptor.
Thanks Frank for a useful
use for unused equipment. Email Frank Hertel at
to Workbench. You’ll help your fellow engineers and qualify for SBE
recertification credit. Send Workbench tips to email@example.com.
Fax to (603) 472-4944.
John Bisset has spent 44 years in the broadcasting industry and is
still learning. He handles West Coast sales for the Telos Alliance.
He is SBE Certified and is a past recipient of the SBE’s Educator
of the Year Award.
Fig. 9: The serrated
copper pipe after it is removed from the mic adaptor.
Fig. 10: Gently bend
the edges to form a tight fit.
Fig. 11: Assemble the
Fig. 12: The finished
product, ready to test.