Build an experimental magnetic loop antenna with a stepper motor and an Arduino
Build an experimental magnetic loop antenna with a stepper motor and an Arduino
Arduino Team — April 14, 2023
Amateur radio allows the broadcasting and reception of non-commercial radio signals over great distances with relatively inexpensive equipment. As the name suggests, amateur radio relies on antennas to operate, and most designs can take up large amounts of space. An alternative antenna is the magnetic loop design which has a large circle of copper tubing around the outside while each end is soldered onto a variable capacitor which is used to tune the signal.
TekMakerUK was inspired by Kevin Loughin's YouTube video on the design and decided to make its own experimental version capable of 5W transmissions, which it could tune via an Android phone. The variable capacitor is from an old valve radio and has a central shaft that rotates to adjust the distance between the dielectric plates. In order to run the coupling, a 5V stepper motor was added to the base with a ULN2003 stepper motor driver. The driver was then connected to an Arduino Uno, although the board was replaced with a Nano Every for the soldered connections.
In terms of usage, there's a digital encoder that increments the count up or down depending on which direction it's turned, and this dictates how far the stepper should move. Calibration of "zero" or home position is done by slowly moving the stepper during initialization until it reaches a limit switch. More details on TekMakerUK's Magnetic Loop Antenna Tuner can be found here on Instructables.
Arduino Team — April 14, 2023
Amateur radio allows the broadcasting and reception of non-commercial radio signals over great distances with relatively inexpensive equipment. As the name suggests, amateur radio relies on antennas to operate, and most designs can take up large amounts of space. An alternative antenna is the magnetic loop design which has a large circle of copper tubing around the outside while each end is soldered onto a variable capacitor which is used to tune the signal.
TekMakerUK was inspired by Kevin Loughin's YouTube video on the design and decided to make its own experimental version capable of 5W transmissions, which it could tune via an Android phone. The variable capacitor is from an old valve radio and has a central shaft that rotates to adjust the distance between the dielectric plates. In order to run the coupling, a 5V stepper motor was added to the base with a ULN2003 stepper motor driver. The driver was then connected to an Arduino Uno, although the board was replaced with a Nano Every for the soldered connections.
In terms of usage, there's a digital encoder that increments the count up or down depending on which direction it's turned, and this dictates how far the stepper should move. Calibration of "zero" or home position is done by slowly moving the stepper during initialization until it reaches a limit switch. More details on TekMakerUK's Magnetic Loop Antenna Tuner can be found here on Instructables.
What's Your Reaction?
