Project-MREAA

Motorized
Rotating
Elevation and
Azimuth
Antenna

I have just finished the build and am working on a guide! Stay tuned!

Update July 10th, 2020

I am still working on this project, but 3 different people which I have asked to 3D print my main ring gear have fallen through (all for different reasons). I am currently working on getting my own 3D printer to print the part myself. Hopefully this project should be finished by August.

Update October 2nd, 2020

Just about done! Need to print one more gear for the azimuth motor, which I’ve had to reprint multiple times due to mis-sizing on the internal hole. I am very behind schedule due to reopening of schools and my part-time job. Finished version should be (hopefully) published by month end. :D

Update October 24th, 2020

I have finished the antenna! With this commit, I am uploading the code for the main and slave Arduinos as well as a setup test for the BNO055. Pictures, videos, parts list, and guide to come shortly!

Update March 7th, 2021

With this update comes a preliminary guide with most of the critical information. It is likely I will add to it in the future.

Full Guide

Here’s a full instruction set on how to build your own antenna and how to wire it

Parts

• 2x Arduino UNO
• 2x Stepper Motors
  • We used these 2A motors
• 2x Stepper Motor Drivers
  • We used these 9-40V drivers
• 1x Orientation device
  • Must have gyroscope and compass
  • We used the BNO055 from Adafruit, which the code is written for
• Batteries to power the Stepper Motor Drivers
  • Must have enough voltage for both drivers
    • In our case, that’s 2x9V = 18V
  • We used 3x 7.4V 610mAh LIPOs we had lying around, wired in series
• Wiring
  • Jumper Wires
  • Longer Wire
    • Enough to where it can wrap several times while the antenna moves

Optional - the following can be changed to fit the needs of the build

Ex: We modified the build afterwards to mount a camera for panorama shots

• 3D printer (gears)
  • Both gears are provided in .stl format and can be found here
• 1/2 inch aluminum square tube (boom)
• 3x copper pipes (director, driven element, and reflector)
  • Lengths depend on frequency of the antenna
• U-bolts
• Sliding door wheels
  • Used to move the antenna on the base
    
• Various other parts as needed…

Steps

Yagi Antenna

Our goal was to receive NOAA weather satellite signals at 137MHz. We sought to make a 3 element Yagi Uda antenna.

We began with rough calculations provided by online calculators. With these numbers we got a piece of 1/2 inch aluminum square tube as the boom. Three copper pipes (one director, one driven element, and one reflector), about 1/2 inch in diameter and cut to the specified lengths, were mounted to the boom at the calculated measurements.

Mounting of the elements was done with U-bolts through the boom. The positive and negative leads were soldered to a length of coaxial cable and the joint was housed in a PVC junction box.

Main Assembly

The whole antenna assembly was mounted on an old skateboard truck with the bearings pressed into two supports that held the antenna off the ground.

Vertical movement was accomplished by means of a screw that was allowed to change its angle to accommodate for the changing position of the stationary nut attached to the boom.

Wiring

Refer to the following diagram for wiring the antenna. A breadboard as displayed is not required, as you can solder the wires as well for a more permanent build.

Extra Photos and Videos

Early wiring and testing of the stepper motor using a compass

First movement to the moon, October 24th, 2020 at 8:06 PM PDT

Tracking NOAA-18