This guide is still under development! Please keep in mind some information here may be incomplete.
Motus Pro Tip - Do not take short-cuts. Any short-cuts or sloppy workmanship drastically increases the chance that some kind of problem will occur and the station won’t be operating when you need it to.
Several varieties of antennas exist of which only a few will be covered here. All antennas should come with their own assembly instructions which are more or less easy to follow so we will not go into great detail here. Please see antenna anatomy for more details on parts.
Note: The driven element and the attached connector are the most sensitive parts of a Yagi antenna; pay special attention to prevent damage to these parts and any connections. Damage to the driven element may cause the antenna to no longer be tuned to the desired frequency resulting in an ineffective antenna.
- Coax seal. This is a type of soft rubber or silicone which is used to seal antenna connections. This is typically purchased separately from the antenna. Marine Goop (with UV protectant (link), and electrician, or plumbers puddy (with link).
- Coloured electrical tape or markers. It can be difficult to keep track of which antenna corresponds with which cable once a station has been set up. Bring a few colours of electrical tape so you can colour code the antennas and coaxial cables.
- Zip ties, cable ties, zap straps. These are indispensable for coaxial cable organisation. Used to support the coax cable along the antenna boom and mast.
- Hex nuts and bolts. We use ¼” x 2” bolts for tripod assembly and ¼” x 1” bolts for affixing solar panels to the tripod**.** Use zinc-plates steel unless the station is deployed in a marine area where stainless steel should be used.
Antennas are usually attached to a metal pipe or mast using a type of mounting bracket. Small antennas, like 434 MHz Yagis, all omni antennas, and 3- to 5- element Yagis for the 150-166 MHz band can be butt-mounted using a bracket which fits onto one end of the boom. Large antennas, like 6- to 9-element Yagis for the 150-166 MHz band need to be mounted along their mid-point to even out the lateral force on the mast. Larger antenna can be butt-mounted, but usually require support wires attached to the mid or end point of the antenna.
Nearly all antenna mounts use a metal plate with 4 u-bolts; 2 for the antenna boom and 2 for the mast. For most antennas, the boom is mounted perpendicular to the mast, but omni antennas will often be mounted pointing straight up, meaning both the antenna and mast will be in the same orientation.
Most antennas will have a connector on the driven element for the coax cable to be connected. The driven element and this connector are the most sensitive parts of a Yagi antenna; pay special attention to these parts so they are not impacted by anything. Damage to the driven element may cause the antenna to no longer be tuned to the desired frequency.
The orientation of an antenna changes the horizontal range relative to the vertical range. For instance, an omni antenna can be oriented straight upwards to have a uniform detectability along the horizontal and vertical axes, or it could be pointed horizontally to create a more restricted, lateral detection area. Similarly, Yagi antennas can be rotated along the boom to select a wider horizontal or vertical beamwidth.
Most stations across Motus will orient their Yagi antennas horizontally (antenna elements pointing horizontal). We recommend all collaborators do this to maintain consistency across the network.
Most Motus stations will host multiple antennas, but this may pose an issue depending on the types and position of the antennas.
Simple modeling by Bob Morton at Maple Leaf Communications suggests there is a significant dropoff in the detection range of Yagi antennas when they are stacked too close together.
We have developed the following guidelines based on these models:
- Antennas that facing opposite directions should be the furthest apart from one-another: at least 1/2 a wavelength (~1 meter for 166.38 MHz).
- Antennas that are facing perpendicular directions should be at least a 1/4 wavelength apart (~1/2 meter).
Antennas should be butt-mounted when possible. This is usually only practical for 434 MHz Yagi antennas due to the size of lower frequency antennas.
What’s the purpose of the storage container - primarily to store and protect battery and charge controller.
Include recommendations to mount receivers on the mast or outside of a box on the ground where possible, or if there is any remote risk of flooding. It will also reduce potential damage from rodents and insects.
Motus Pro Tip - DO NOT USE cheap plastic rubbermaid, or other plastic storage boxes that are not meant to be kept outside for extended periods of time.
- 90L Rubbermaid Action Packer or equivalent heavy-duty, waterproof container.
- If using an alternative, ensure the container is actuallywaterproof and the lid is not concave such that water pools ontop. Handles will need to be closed securely either with zipties or a lock.
- To prevent water ingress:
- Electrical tape or ABS cement
- Zip ties
- [Optional] To prevent insects and rodent ingress
- Plastic bags and/or steel wool.
- Aluminum window screening.
- JB Weld epoxy or equivalent.
- Container and stir stick for epoxy.
- Tool to cut into underside of container (e.g.: exacto knife).
- 1.Drill 2” hole on one end of the Action Packer, about 6" from its base.
- 2.Place the 2-inch pipe bushing through the hole from the inside of the bin.
- 1.Apply a single layer of electrical tape or ABS cement to the exposed end of the bushing on the outside of the bin.
- 2.Attach the 2-inch pipe elbow to the bushing from the outside of the bin and force into place with the open end of the elbow pointing down.
- 3.Using the 1/4" drill bit, drill a couple holes in each of the bottom corners of the bin. This is to prevent water from pooling if it gets in somehow.
- 3.[Optional] To prevent insect and rodent ingress
- 1.Cut a pieces of aluminum window screen large enough to cover the holes drilled into each of the corners of the bin.
- 2.Prepare the epoxy
- 3.Place the piece of aluminum window screen over the hole and apply a generous amount of the mixed epoxy around the entire edge, ensuring no gaps remain.
- 4.Once you have inserted all necessary cables into the bin, including your GPS and SensorGnome, you will need to pack the remaining space in the elbow with plastic bags (insects) and/or steel wool (rodents).
- 1.Prepare your cables by crimping 14 AWG spade connectors to the ends of all your cables.
- For the battery, prepare one **** fused battery lead __ and one length of the 14 AWG stranded automotive/speaker wire.
- 2.Carefully inspect the charge controllers and note the positive and negative terminals for: the Solar Panel (input); the battery; the load (output).
- 3.Ensure the power rating on the back of the solar panel does not exceed the ratings of the charge controller.
- 4.Loosen the positive and negative terminals of the battery and attach the battery cable one at a time, using a fused battery lead for the positive terminal and 14 AWG stranded automotive/speaker wire to the negative terminal.
- 5.Loosen the positive and negative terminals for the battery on the solar charge controller and attached the battery cables, beginning with the positive side.
- 6.Proceed to connect the solar panel cables to the solar charge controller, again beginning with the positive side.
- 7.Finally, connect the load (receiver) to the load terminals of the solar charge controller, positive first.
Motus Pro Tip
Sometimes the charge controller may indicate the battery level is low, or will cycle through different levels when first connected. This is normal as it is calculating the average voltage over time to gain an accurate measurement.
A pop-tower is a type of standalone station that uses a tripod + telescopic mast assembly to mount the antennas. The tripod can be used to mount a solar panel if necessary.
- Must be flat and void of obstructions so antennas have a clear line of site.
- Cannot be near any elevated power or telephone lines for safety reasons.
- Tripod feet will sink into soft ground - use gravel or choose a hard/dry location to install. Also affix pieces of wood to each tripod foot to support the weight and movement and to prevent sinking (‘snow-shoe).
- Ground must be soft enough to insert anchors (1 m/3 ft. or more, depending on hardness).
- Choose a well-elevated site to avoid any risk of flooding during heavy rains or tidal surges.
- Footprint of a pop-tower with guy wires has a radius equal to 70% of the tower’s final height.
- Pop tower
- Wooden blocks (optional)
- Foot for mast (optional)
- Guy wires (1/16 galvenized for inland sites; 3/32" stainless for marine areas)
- Quick links and/or carabiners (max 3/16”)
- [Optional] Turnbuckles with nuts or stainless steel wire (snare wire)
- In-line wire tensioners.
- Impact driver and/or ratchet
- 7/16” socket
- ½” deep socket
- Ratchet with ½” drive
- Cobalt drill bits (or equivalent) for metal drilling.
- 3/16" and 1/4"
- Phillips/Robinson’s screwdrivers for screws
- 1.Assemble the tripod according to instructions provided by the manufacturer.
- It is easiest to install the TRM-10L with it lying on its side.
- 2.Insert mast into the center of the tripod. Bolts on the tripod's centre brackets may need to be loosened to allow space for the mast to slide through.
- 3.Attach foot to base of mast.
- 4.Attach lower guy wires to the lower guy ring using quick links or carabiners.
- 5.Place tripod + mast assembly upright.
- 6.Position the assembly so the mast stands level and the tripod legs are on stable ground.
- 7.Screw on wooden blocks to the tripod legs to prevent them from sinking into the ground. This is suggested for most installations as the ground will soften in the spring and fall.
- Alternatively, you can bury cement blocks filled with sand foreach foot to stand on.
- 8.If you are mounting a solar panel, rotate the tripod so that the ‘ladder’ side with four crossbars is facing south.
- 9.Place three anchors 7 feet (2 m) from the base of the mast such that once the guy wires are attached they are between the tripod legs.
- If using angle iron
- 10.Attach the loose end of the lower guy wires to each anchor.
- 11.Tighten the guy wires with:
- In-line wire tensioner:
- 1.Remove tensioner lock.
- 2.Place guy wire in the slot of tensioner.
- 3.Insert ½” drive ratchet into square slot of tensioner.
- 4.Use the ratchet to tightly spool guy wire until taught, but not too taught.
- Tripod legs will lift off the ground if too tight, orthe mast will bend.
- 5.Insert tensioner lock in opposing holes to keep guy wire in place.
- 6.Multiple tensioners may be necessary if there is too much excess guy wire.
- Turnbuckle: https://www.youtube.com/watch?v=zz_nS79_JDg&t=386s
- 1.Before all guy wires are taught, loosen the turnbuckle until only 2 full turns remain.
- 2.Tighten guy wires, either with in-line wire tensioners or another method.
- 3.Use turnbuckles to finely adjust wire tension until all sides have equal tension.
- 12.Confirm tower is being held securely in place by guy wires by inspecting each end of all guy lines to ensure it is properly attached.
- 2.Finger-tighten the U-bolts which attach to the antenna boom such that it can still rotate.
- 3.Loosely-attach the second set of U-bolts.
- 4.Coaxial cables should already be attached, sealed, and zip-tied to the antenna boom (one tie by driven element, a second tie by the mounting bracket).
- 5.Ensure the tripod is securely guyed at the base and is safe to climb.
- 6.Climb the tripod of the tower and pull out some of the top-most section of masting from the telescopic mast.
- 7.Slide the U-bolts of the antenna mounting bracket onto the mast and allow it to rest on the guy ring at the top of the tripod.
- 8.Rotate the antennas such that the elements are horizontal and then tighten the U-bolts which affix the boom to the mounting bracket. Don't tighten the U-bolts attaching the antenna mounts to the mast - this will be done later.
- 9.Slide on all other antennas in a similar manner (steps 7 and 8) except for the top-most.
- 10.Securely attach the mast collar approx 30 cm (1 foot) from the top of the mast and then slide on the spare guy ring and attach the top-most guy lines (they don't need to be anchored yet).
- 11.Slide on the last antenna and attach it securely in place approximately 15 cm (6") from the top (~15 cm above the guy ring).
- 12.Mark out planned antenna directions on the ground using visual markers so you can easily point antennas in those directions.
- 13.Determine the height of each antenna based on our guidelines for stacked antennas and then colour-code each antenna and coax cable so that they can be identified when plugging them in to the receiver.Our convention: port 1 = top (red or 1 stripe), port 2 = middle (yellow or 2 stripes), port 3 = bottom (green or 3 stripes).
- 14.Before raising the mast, ensure all guy lines and coax cables are uncoiled, and that the antennas and coax are colour-coded.
- 15.While holding the top-most section of masting with one hand, loosen the top-most L-bolt and then begin raising the mast.
- 16.Once there is adequate space between the upper-most antenna, tighten the L-bolt so the mast stays in place and then fix the next antenna to the mast, ensuring that both the top and middle antenna are pointing in the intended final direction.
- 17.Repeat steps 15 and 16 until all antennas have been fixed to the mast.
- 18.Continue raising the mast section until the hole below the L-bolt no longer shows metal on the inside.
- 19.Once the mast section has been raised, slide a 3-inch bolt through the hole below the L-bolt for that section and then allow the top section to rest on top of that bolt.
- 20.With the top mast section resting on top of the bolt, rotate it until it locks in place and starts rotating with the section below it. Tighten the L-bolt.
- 21.Continue raising mast sections (following steps 18-20) until the desired height has been reached. Don't worry if the angles aren't perfect - you can adjust the whole mast at the end.
- 22.If at the final height you cannot fit the 3-inch bolt into the hole below the L-bolt (because the inner masting is in the way), you can drill through the masting to insert the bolt. Make sure you lock the L-bolt in place!
- 23.Ensure the bolts on the tripod's centre brackets are loosened and then rotate the entire mast to it's final position (you may need 2 people to do this).
- 24.Tighten the centre bracket bolts, being careful not to dent the mast.
- 25.Place guy wire anchors at a distance from the mast that is approximately 70% of its height on the mast.
We recommend using rubber tubing around the antenna boom where the mounting bracket attaches to help reduce slippage. A bicycle inner tube is the perfect diameter to fit around the 1 1/2" boom.
It's easier to mount antennas when the coax cable is mostly coiled, uncoiling it only after it has been attached to the mast.
Measure your antenna directions at least 5 meters from the base of the tower and any other large metal objects, otherwise your measurements will be inaccurate.