{"id":1345,"date":"2016-08-17T05:56:40","date_gmt":"2016-08-17T11:56:40","guid":{"rendered":"http:\/\/play.fallows.ca\/wp\/?p=1345"},"modified":"2017-02-21T13:12:50","modified_gmt":"2017-02-21T20:12:50","slug":"magnetic-loop-material-choices","status":"publish","type":"post","link":"https:\/\/play.fallows.ca\/wp\/radio\/ham-radio\/magnetic-loop-material-choices\/","title":{"rendered":"Magnetic Loop Material Choices"},"content":{"rendered":"

\"Magnetic<\/a><\/p>\n

Now that I have a butterfly capacitor working, it\u2019s time to select my magnetic loop material.<\/p>\n

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Materials used for magnetic loops must be highly conductive metals. Almost always, this means copper or aluminum. These materials might be formed into pipes or tubes, foils or flashing.\u00a0 To minimize electrical losses, it is advantageous to use a continuous length of material, rather than soldering or braising shorter pieces together. You also want to maximize the magnetic loop material diameter. The lower your frequency, the higher the diameter required.<\/p>\n

There are two neat things about radio current flowing along conductors. The first is called \u201cskin effect\u201d. No matter how thick your material is, the radio current flows along the outer surface, or the skin. So, for my frequencies of interest, the power stays in the outermost 0.005\u201d (5 mils) of the material. This means that you can use the thinnest wall copper pipe, or even substitute copper foil wrapped around a plastic (PVC) pipe. The second neat thing is that there is an equivalence between flat metal strap or flashing, and round piping. Using flashing can work just as well as pipe and can give you a weight advantage.<\/p>\n

So, I evaluated all of these loop material choices against my design goals. Basically, I want my first loop to:<\/p>\n