Radio Patents

John’s list of interesting radio patents

Radio Patents relating to signal propagation along a wire

Interference attenuating power conductor utilizing intensified skin effect to attenuate high frequencies
US3219951, 3 May 1963

Radio Patents relating to mitigating Passive Intermodulation (PIM) products in ferromagnetic materials

The next two patents describe a technique whereby passing a strong static magnetic field through a PIM prone ferrous material, such as a nickel plated RF connector, reduces the generation of PIM. This technique is likely in the public domain by now, but the recent Purdue patent application is an interesting read nonetheless.

Method of reducing spurious signal generation in passive microwave components
US4156857, 2 May 1977
This patent showcases prior art to the patent application US20120139656 below. It doesn’t patent the method of using a magnetic field to mitigate PIM in ferrous materials specifically, but does describe the method in its descriptive wording as if it is common knowledge.
Magnetic field system and method for mitigating passive intermodulation distortion
US20120139656, Application 4 Jun 2009 – Purdue University IDEAS Lab
This patent application’s first claim describes a method that seems to already exist in Prior Art above.

The folks at Purdue have a spiffy video demonstrating the effect…

You need to a flashplayer enabled browser to view this YouTube video

Various Patents