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Shielding Microwave Interference
Name: Lois A.
Status: other
Age: 60s
Location: N/A
Country: N/A
Date: 9/22/2004
Question:
Operating my microwave which is near my TV in my kitchen
(about 10 feet apart) causes significant noise/picture distortion on the
TV. My TV is receiving satellite pictures remotely from my bedroom
TV/satellite receiver. Is there a way to shield the TV?
Replies:
It sounds like you are saying there is an in-home wireless link
from the satellite receiver in your bedroom to the TV in your kitchen.
This kind of link is often done by means of "radio at 2.45GHz".
2.45 GHz is the frequency of microwave ovens, too.
Microwave ovens are _allowed_ to leak many milliwatts of microwave power
into the air around them.
So this is a bad frequency to use for radios nearby, trying to listen
carefully to faint signals.
What needs shielding from your microwave is not the TV,
but the receiving antenna of the wireless link next to the TV.
Try putting a metal sheet at least 1 foot x 1 foot adjacent to the
wireless receiver,
blocking its view in the direction of the microwave oven,
but not blocking it's view in the direction of the wireless transmitter in
your bedroom.
Aluminum foil works fine and is quick to test with; perhaps later you'll
wish to replace it with something that looks better.
Likewise, at the microwave, try putting a 3-foot x 3-foot sheet near it,
blocking its view of the TV wireless receiver.
Together these two places of shielding are more likely to work than either
one alone.
If I'm right, trying both together should produce a noticeable improvement.
Actually, a human body or three between receiver and microwave might make
a noticeable change,
and by blocking the leakage wave where one stands, show you the path the
leakage travels from microwave to TV.
(If these do not help, there is some other channel of interference.
In that case, try making sure your TV is not plugged into the same socket
or electrical fuse-circuit as your microwave.
I.E., just for a test, run the TV on an extension cord from the living room.)
However, it is possible that enough shielding to completely fix your
problem is impractical.
The receiver is looking all the way through the house to the transmitter,
and microwave signals from the oven can bounce faintly off walls and
strongly off wires and pipes.
They are all partial mirrors and shiny scattering points. Metal boxes
like refrigerators are strong mirrors.
What would work best is to run a coax cable from the TV to the bedroom,
eliminating the radio link.
A partial step to this might be to run cables part-way towards each other,
so the wireless link has a much shorter air-travel distance.
Be sure to carefully point the wireless receiver antenna towards the
transmitter and away from the microwave,
and perhaps give the antenna metal shielding across its back as well.
For homes these days, good electronic connectivity tends to be at odds
with good cosmetic appearance.
Any cosmetic compromising coax cable you're willing to accept might make
your TV work better.
Or perhaps hiring an electrician or a savvy friend might help get one
cable installed well.
Jim Swenson
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Update: June 2012
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