Antenna Construction V2
After constructing the first antenna I felt dissatisfied with the time it had taken to fabricate the antenna and its overall quality. Specifically I was disappointed with the time it had taken to drill holes and their alignment as well as the time it had taken to bend the dipole into the correct shape. I was also concerned that any significant differences in two antennas could lead to a decrease in the performance of the antenna array and its ability to orient itself using RSSI values. To correct this I came up with a few parts which can be made on the 3d printer and allows for the creation more reproducible antennas.
Antenna Mast Corrections
To ensure all of the holes on the antenna were as close to perfectly aligned and spaced as possible I created the following part using my 3D printer. The part is shown below.
I made a total of 15 of the parts. They are used to space each of the reflectors/directors of the antenna. They work as follows. First a spacer with holes 30mm apart is used to align the hole for the antenna reflector. This is done by inserting a straight section of copper tube into the partial hole at the top of the part. Part can then be slid onto the PVC tube until the copper tube prevents it sliding further. Once this is done the lower extended hole can be used to align and straighten the 1/4" drill bit to drill a hole for the reflector. Once the reflector hole is drilled the copper tube can be inserted into the hole in the PVC pipe. The next part which is sized for the distance between the reflector and first director is then selected and slid onto the pipe. The part is slid up until the reflector is pushed into the upper semi circular indentation. The part is designed so that the part will fit snugly onto the copper tube and will not fall off of it. View the image below for details.
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Once the spacer is snapped onto the reflector its flat lower edge can be placed onto the table of the drill press. The press table can then be aligned so that the drill bit is partially inserted into the guide hole. Finally, clamp the spacer down and drill the hole for the next director. This process can be repeated with each spacer until the antenna is complete.
Folded Dipole Correction
In order to fix my concerns with the dipole fabrication I printed the following part.
This part is designed to allow the copper tubing to fit into the inner groove. The square cutout in the part allows the end of the copper tubing to be clamped in placed. Once the tubing is clamped in place, it can be bent around the part to create the ideally shaped dipole. If any piece are not straight, they can be bent into place using the clamp.
Suggestions for users
If I ever have the need to make additional antennas I would likely modify the spacers so that rather than have a semi circular hole, they would have a circular protrusion. This way instead of snapping the spacer onto the copper reflector/director, each spacer could just be inserted into the existing hole. This would make the process of drilling holes for the antenna easier because the copper tube often makes drilling more difficult. The part I am thinking of would look something like the part shown below. This part though would be harder to print. For access to the parts in this tutorial visit the link below.
