WiFi Antenna Alignment

Proper antenna alignment is critical for the highest bandwidth and most reliable signal. Follow the recommendations below to easily align your antenna.

A properly installed mounting pipe is essential for proper antenna alignment

• For smaller devices, a 1.5" or 2" IMC or Rigid conduit works well.
• For 31 dB or 34 dB dish antennas, a 2" IMC or Rigid conduit should be used. This gives these larger antennas more clamping surface.
• Make sure the pipe is exactly vertical or plumb. If the mounting pipe is not vertical, it will be nearly impossible to properly align the antenna.
• Make sure the pipe cannot move or vibrate, even with strong winds blowing on the antenna.
• Make sure the structure holding the pipe will not be damaged by strong winds blowing on the antenna or shaking from an earthquake.
• Follow all applicable building codes.

Larger dish antennas will need a "stiff arm"

• Larger dish antennas, such as the Ubiquiti 34 dB dish, present a large surface area to the wind, which can place a lot of rotational force on the mounting clamp. Sadly, the Ubiquiti 34 dB dish has a terrible mounting clamp that does not provide enough clamping force to prevent the antenna from being pushed off axis to the left or right by the wind.
• The solution to this problem is a "stiff arm". A "stiff arm" or tieback bracket is a pipe that runs from the edge of the antenna back to a solid location and prevents the antenna from being moved left/right.
• Sadly, the Ubiquiti 34 dB dish does not come with a stiff arm. But one can be crafted easily enough to connect to one of the bolts used to attach the shroud. Once properly installed, the dish will not move, even when forceably pushed.

• Mount the antenna on the pipe.
• If the antenna is heavy, such as a dish, install a clamp below it and rest the antenna on the clamp. This will allow you to swing the antenna left/right without it slipping down the pipe.
• If the antenna has a bubble level on it, adjust it so that it reads level. This is important for aligning the vertical and horizontal polarities of the dual-polarity signal.
• Set the elevation angle to the value provided by SCCo ARES/RACES network team. Some antennas have elevation angle markings. Or, you can use a level that has pitch/slope indicators. You can find them for less than $10 at a hardware store or on Amazon.
  • Example: https://www.amazon.com/Johnson-Level-Tool-700-Magnetic/dp/B00004T807/
• Swing the antenna to the azimuth provided by the SCCo ARES/RACES network team. You will be provided with two azimuth values: one relative to true north; the other relative to magnetic north. Be sure to use the right one, depending on how your compass is configured.
  • Note that on commercial rooftops, compasses frequently don't work well due to interference from lots of metal structures and air handler motors. In such environments, set the azimuth as best you can using visual alignment. Binoculars or a spotting scope can be very helpful.

• Initial aquisition of signal
  • The radios take approximately 30 seconds to boot up. Once booting is complete, the radio will begin searching for a signal.
  • When the radio first acquires a signal, it can take upwards of an additional 30 seconds to connect and start displaying useful info (in the lights and in the app). So, you need to go VERY slowly at first or you will move right past the signal before the radio displays anything. This is especially true of higher gain antennas, such as 31 dB or 34 dB dishes, which have an angle of view of about 5 degrees and 3 degrees, respectively.
  • If the radio has signal strength lights, they can be helpful for initial signal aquisition.
• General alignment info
• Once you have aquired a signal, you can move a little faster as you fine tune the alignment. Move a degree, wait a few seconds, check the signal strength, monitor for a few seconds to make sure it is stable. Then repeat.
• Use the "Alignment" tool in the web user interface for actual antenna alignment. It displays the signal level of both the horizonal and vertical signal chains in 1 dB increments. This means you usually need two people to align the antenna properly: one to monitor the screen while the other moves the antenna.
• Do NOT rely on the signal strength lights on the radio (if it has them) for anything more than aquiring the initial signal. They are very rough measurements which will help you get pointed in the general direction of the access point. But they will NOT show you the best alignment.
• Start with azimuth
  • Slowly swing the antenna in one direction. Move a degree at a time and then pause to let the signal measurement stabilize. Repeat until you max out the signal.
  • If you are unable to find the signal, go back in the other direction.
  • Once you max out the signal, keep going past it by a few degrees to verify that the signal level decreases. Then come back to the maximum signal. This ensures that you are aligning to the main signal lobe and not a side lobe.
  • Tighten the clamp enough to keep it from moving.
• Next, adjust the elevation
  • Move the antenna up or down a degree at a time and stop. Repeat until you max out the signal.
  • As with azimuth, once you max out the signal strength, keep going past it by a few degrees and then come back to the max signal to make sure you're on the main lobe.
• Fine tune the azimuth
  • Repeat the above procedure for the azimuth, moving one half degree at a time. At this point, only very small movements should be needed.
• Fine tune the elevation
  • Optionally, repeat the above procedure for the elevation, moving one half degree at a time. Usually this is only needed with very high gain antennas, such as 31 dB or 34 dB dishes.
• Check your results
  • The received signal strength should be at or very close to (within 1-2 dB of) the predicted signal strength provided by the SCCo ARES/RACES network team.
  • The horizontal and vertical signal strengths should be nearly identical, perhaps differing by only 1 or 2 dB.
• Tighten everything down
  • Monitor the signal strength while you tighten everything down. It's not unusual for the antenna to move while you tighten the clamps. If it does, loosen the clamps and try again.
  • Be sure you tighten all adjustments (elevation, azimuth, rotation).
  • If you have a Ubiquiti 34 dB dish, also attach and tighten down the stiff arm. Again, be sure to monitor the signal strength to make sure you do not move the antenna.