Making an antenna pan-tilt rotor just requires a few cheap parts.
The pan-tilt assembly was around $2, and is designed for mounting a first person view (FPV) camera on an RC vehicle. It is sized to work with two really cheap ($2) micro-servo motors. These servos are very light weight and have limited torque (around 45 oz-in.) But I thought they might be strong enough to move a frame loop antenna as long as it was not too heavy.
Servo motors have a normal range of 0-180 degrees. One motor would be used to rotate the antenna. The other would tilt it. Since the loop antenna is bi-directional, rotating it only requires 180 degrees, not the full 360. The tilting would only need about 60 degrees.
To make this work, I 3D printed some plastic parts. The orange part shown above is a base mount. The round section fits snugly inside a piece of PVC tuning, as a way to mount the antenna. The pan-tilt assembly screws into it. The blue part shown above holds the antenna frame to the pan-tilt structure.
For the antenna frame, I bought two 4-foot pieces of 3/8” hardwood dowel. This will allow me to build my square receiving loop with 34” sides. Later I will print some wire holders for the end of each dowel. The dowels weigh about 8 ounces. The wire loop will add a few more ounces.
Arduino runs the antenna pan-tilt rotor
It is quite easy to control servos with an Arduino. Each motor has three wires: 5V, ground and control. Control is provided by sending a pulse width modulated signal (PWM) from the Arduino to the motor. The Arduino Servo library simplifies the whole process. First, you set up one digital output pin to be the control line between the Arduino and the servo. After that, you just write a control number between 0-180 and the servos will turn to that position in degrees. Several servo’s can be controlled at the same time.
I hooked up a couple of buttons to increase or decrease the pan and tilt. And, the next thing I knew, the loop frame was rotating and tilting. These little servo motors and plastic parts should do the trick. An antenna pan-tilt rotor for $6.