{"id":5729,"date":"2019-06-25T05:45:43","date_gmt":"2019-06-25T11:45:43","guid":{"rendered":"http:\/\/play.fallows.ca\/wp\/?p=5729"},"modified":"2019-06-24T10:18:16","modified_gmt":"2019-06-24T16:18:16","slug":"magnetic-loop-compendium-summary-of-work","status":"publish","type":"post","link":"https:\/\/play.fallows.ca\/wp\/radio\/shortwave-radio\/magnetic-loop-compendium-summary-of-work\/","title":{"rendered":"Magnetic Loop Compendium – Summary of Work"},"content":{"rendered":"

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

For the past five years I have experimented with magnetic loop antennas. I thought it was time to publish a magnetic loop compendium of my work, complete with links to all articles.\u00a0<\/p>\n

My experience with design, construction and use of magnetic loop antennas really started in the fall of 2014. I was searching for the sources of RFI in my neighborhood. To support these efforts, I built a quick and dirty tuned loop covering 2-20 MHz, shown above as #1. It contained switchable frequency range and resistive attenuation. You can see this DF loop in detail in my video Adventures with Radio Frequency Interference<\/a>, at the 13 minute mark.<\/p>\n

Next up in the magnetic loop compendium was my 40-10 meter small transmitting loop<\/a>, shown above as #2. This was a five foot diameter copper tube, with a home made butterfly capacitor. I motorized the tuning with a stepper and plastic gears. My local WIFI enabled remote tuning.<\/p>\n

Built in the spring of 2015, my STL was really an internet-of-things project leveraging my home made 3D printer for gears and mounting and CNC machine to mill the capacitor plates.<\/p>\n

My final tuned loop, shown as #3, covered medium wave and lower short wave bands<\/a>. This was a multi-turn loop made of magnet wire mounted on a 2′ square frame made from dowels and plastic. You will see innovations in this summer 2016 loop included wired remote control, azimuth and elevation rotation using servo motors. Also, I used relays to switch tuning range and a digital-to-analog converter to provide tuning voltage for the varicaps.<\/p>\n

All of these projects produced working products and were a lot of fun to build. But then I decided to take the leap into active wideband receiving loops, which work on very different principles.<\/p>\n

Magnetic Loop Compendium – Going Wideband<\/h2>\n

Last year, I bought an Afedri dual channel coherent receiver. I thought it might be fun to build some spaced active loops to experiment with spatial filtering, including noise reduction and diversity reception.<\/p>\n

Over the past six months, I have written several series of articles describing:<\/p>\n