Extend your Reach: 9m portable antenna mast

[bide]

If the skyview won’t reach you, then you reach the skyview!

I thought I’d share some pictures of my low-budget 9m (30’) portable antenna mast in operation. It is constructed of thin-walled PVC drainage pipe.

You can barely see it here as a small white line in the center of the picture:

Closer:

And closer:

At night, looking up the plumb bob string. You can see the plumb bob string, the power cable, and the 3 guy wires.

It takes a minimum of two people to raise the mast safely. One to hold the bottom to the ground, while the other lifts up the top and walks along while lifting higher and higher. The mast can be leaned up against a nearby tree while waiting for the guy wires to be tied. Alternatively, a guy wire can be tied before raising the mast, and one person can balance the mast by putting some strain against the guy wire. It is possible for one person to hold the mast alone, but it can be very difficult. One person might even be able to raise the mast by themseves, but I would not recommend it.

For transport, tape the 3 sections of PVC drain pipe together side-by-side. Put that over your shoulder, and the rest can be carried in a back back.

Components:

• Battery pack
• 10.5m (35’) 12Volt, 16AWG, 2-conductor extension cable with USB power adapter attached
• The Reach unit
• The antenna mounted to a steel sheet metal ground plane
• The ground plane bolted to a PVC drain grate fitting underneath
• A ring for the plumb bob string attached to the drain grate under the center of the antenna
• A PVC wye fitting screwed to a PVC 45 degree street elbow
• The plumb bob with 18m (60’) of string
• Not shown: 3 guy wire strings approxImately 15m (50’) each
• Not shown: 3 sections of perforated PVC drain pipe 76mm (3") diameter by 3m (10’) long
  
  

Components shown ready for assembly. Ground plane gets put on top of PVC wye fitting, and that gets put on top of PVC mast. Center of antenna is offset to the side of the PVC mast. Plumb bob string goes from the ring under the antenna, straight through the PVC wye fitting down to the ground.

Showing the antenna cable held to the inside of the PVC wye fitting with electrical tape to keep it from interfering with the plumb bob string.

The plumb bob in action. Loosen or tension the guy wires to center the plumb bob over the marker.

The battery pack in waterproof container with cover removed.

Very professional waterproof container for the Reach unit and also the USB power adapter. This bag is sealed as best it can be, and gets taped to side of PVC wye fitting. The power cable gets heavily taped to side of PVC wye fitting to provide strain relief for the wires. You should probably do a better job than this.

This is what my base station lives in:

Rain water could enter the container along the antenna wire. I will tip the container slightly so the water runs off, or pay closer attention to the way the cable lays so that the water will drip off before entering. So far my equipment has stayed dry in very heavy rains.

[Luke_Wijnberg]

Cool setup. The beauty of the Reach is that it is so light that you can mount it really high up without it being too top heavy.

[mikhail.avkhimenia (Mikhail)]

This is pretty cool:)

[egor.fedorov]

@bide

Very professional waterproof container for the Reach unit and also the USB power adapter.
You should probably do a better job than this.

[bide]

Yes, I should be ashamed of the plastic bag. Reach deserves a better house to live in. I have some nice Pelican cases which are planned to hold Reach and the RFD900 radios.

[edmund89sg]

High five to you… I also use PVC pipes as my makeshift pole antenna, but only 2m just for GIS data collection. Yours is something else.

[bide]

@edmund89sg

I also use PVC pipes as my makeshift pole antenna, but only 2m just for GIS data collection.

That’s great! Post a picture if you’ve got one. I’m interested to see other people’s ideas for antenna masts - especially if it is cheap!

[igor.vereninov]

This is really cool! How long does it take to measure one point and move the whole thing to the next one?

[bide]

Right now it is taking two of us about 40 minutes for set up and 20 minutes for take-down. With practice, it could be done much faster. The main time-waster is clearing the guy-wires from being snagged in tree branches, and secondarily the centering of the plumb bob involves several adjustments to the tension of the guy wires.

If you were well organized, I’ll bet it could all be done in 20 minutes plus your occupancy time.

I’ve been post-processing, so if Reach has really good satellite view, I’ll occupy for minimum 20 minutes to guarantee a fix. With radios, I suppose it occupancy time would be down to about 5 minutes.

Several times the mast is still not high enough to get an immediate fix. In those places I will set up in the evening and take down in the morning and as the satellite geometry changes, sometimes that will produce a fix. Now, that is a lot of unnecessary data collection, but the alternatives are:

• higher antenna mast
• cut down trees
• use an optical instrument to offset from a place with better sky view.

[bide]

EVEN HIGHER NOW

as if 9m was not enough

• 13.5m telescopic pole
• collapses down to 2m
• light weight < 5kg

[igor.vereninov]

Awesome!!

[bide]

Thanks! Unfortunately it is not low-budget, but it is very portable, and you can wash the windows up to the third storey of your apartment building with it. It can even be hand-held over a monument somewhat steadily at full extension and without the guy wires.

It feels a bit like fishing with the plumb bob as the lure and the monument as the fish.

[RTK]

That is very cool.

So your just using one Reach module to get the L1 carrier phase fix logging so you post process later against a correction data network?

I wonder how long it would take to get a fix if one used two reach modules (if you don’t have a mast), one in a open field nearby, and one under the forest during the winter time with no leaves.

I’m new to all of this, does anyone know how one could tell if there is a live fix or not it using an RTK set up?

I was thinking if one used two reach modules (one in field and one in forest) the current location might could be plotted on a computer tablet or phone map. If you zoomed in far enough perhaps you could tell if there is a fix by moving the Reach module in the forest back and forth several centimeters to see if there is indeed a fix, if not then maybe the current location marker would drift around the map with no movement of the module? Could this be a good way to tell if there is a fix? Even it the fix lasted only 10 seconds at a time in the forest, that would be enough time to compare to base map objects or markers.

[egor.fedorov]