[RFI] EMI Tape?

[James Gordon Beattie Jr]

Kurt,
It is used in the cellular industry to cover bi-metal junctions that are sources of near field Passive Inter-Modulation (PIM).  The tape blocks the RF sources from mixing at these points and prevents the generation of additional interfering signals at frequencies used by receivers at a site.

In other cases, the RF sources involved are simple harmonics from high power FM transmitters.  For example, a 101.1 MHz transmitter can produce a strong 7th harmonic on 707.7 MHz which is in the middle of a cellular uplink passband. Interference there can crowd out weak cell phone signals.  I've seen cases where the spectral purity from the FM broadcaster's antenna is fine, but a poorly designed, or missing cover on the transmitter itself is allowing for unfiltered RF harmonics to be emitted.  Tape has been applied to either fix the problem, or to convince those involved to implement a more permanent solution.

There are other uses, but these are two common applications.

73,
Gordon Beattie, W2TTT
201.314.6964

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________________________________
From: RFI <rfi-bounces+w2ttt=att.net at contesting.com> on behalf of KD7JYK DM09 <kd7jyk at earthlink.net>
Sent: Wednesday, June 16, 2021 1:27:58 AM
To: Rfi List <RFI at contesting.com>
Subject: [RFI] EMI Tape?

Who's playing with this, what is your application, and results?

https://www.ebay.com/itm/121739046153

I've seen it in equipment since the 90's, bought a roll a couple years
ago, just haven't gotten around to using it.  Wondering what others are
doing.

Kurt
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