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RF and attic antennas

Oct 2nd 2020, 08:56


Joined: Aug 22nd 2020, 09:18
Total Topics: 0
Total Posts: 0
I have a large attic with a tall peaked roof. I can fit an MFJ Cobweb 1838 in this space (20+ feet above ground). Maximum power of transmission will be 200 watts.

Should I be concerned about RF below this antenna, especially on the 2nd floor?

Is there any way to reduce RF penetration to the floor below?
Oct 5th 2020, 05:43


Super Moderator

Joined: Apr 4th 1998, 00:00
Total Topics: 0
Total Posts: 0
An All-Band Attic Antenna
Kai Siwiak, KE4PT, describes how to make an effective inverted L with an Icom AH-4 autotuner. QST October 2007 pp. 33-37.

This article describes how one may go about evaluating the RF exposure of an attic antenna. It can be frustrating to deal with the inevitable detuning of indoor antennas unless you use an autotuner. But, you can support a large somewhat fragile structure that wouldn't survive for very long outdoors.

Zak Lau W1VT
ARRL Senior Lab Engineer

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