Another Small HDTV UHF antenna

thingiverse

This is inspired by https://www.thingiverse.com/thing:1729860. That design works surprisingly well. This variation is designed to mount to a piece of 1" PVC pipe and to allow easy stacking for better signal strength. My PVC pipe measures 1-5/16" diameter. There are two designs for the active elements. Design 1 is a V shaped wire bent at about 30 degrees and about 7" (178mm) long on each side of the V. Start with about 16" (406mm) and bend the wire in half. Spread the wire and trim each side to length. Use a washer on each side of the element. Design 2 is a classic bent bowtie that approximates the elements I remember from my time as an antenna installer. Print the elements then cover with foil. I used aluminum tape that is used for sealing air conditioning ductwork. You could also use a thin sheet of metal for the element. For either design, holes are included so that multiple antennas can be stacked. There is not much difference in signal strength for two stacked antennas but there are fewer dropouts due to nearby trains and airplanes. I found that the best performance was with the feedpoints on each antenna about 7" apart. The clamps on the PVC pipe allow the spacing to be adjusted easily. The element holders mount to the center bracket with #6-32 screws. The elements mount to their holder with #6-32 or #8-32 screws. Use washers around the element mounting screws to ensure electrical conductivity. The PVC clamps use #10-24 hardware. The reflector elements should be of equal length, about 16" (406mm) long. The exact length is not too important, but the elements should all be close to the same length. Insert the elements into the center bracket about halfway. Place an end cap over each end of the wires. Friction should hold the elements in place but if you have any problems a couple drops of super glue should keep them from moving. You can also build this design with just the active element and mounting bracket without any reflectors. Option 1 - Wire antenna, no reflector 1 ea center bracket 1 ea center wire feed 2 ea pvc clamp 2 ea stiff wire, about 3 mm OD, 16" long Option 2 - Bowtie antenna, no reflector 1 ea center bracket 1 ea center bowtie feed 2 ea pvc clamp 2 ea bowtie elements Option 3 - Wire antenna, with reflector 1 ea center bracket 1 ea center wire feed 2 ea pvc clamp 2 ea reflector end 7 ea stiff wire, 3 mm OD, 16" long. 5 wires for the reflector and 2 for the active element. This is about the same performance as the original 1729860 design Option 4 - Bowtie antenna, with 1 ea center bracket 1 ea center bowtie feed 2 ea pvc clamp 2 ea bowtie elements 2 ea reflector end 7 piece stiff wire, 3 mm OD, 16" long If you want stacked antennas, build two of the same option with an extra center feed. Insert the wires into the center feed at each antenna and connect the coax halfway between the two antennas. I used a hard plastic covered clothesline wire for the wire elements and the reflectors as it was cheap and readily available. The printer settings probably aren't critical. I used: Printer - I3 clone Slicer - IdeaMaker Layer height - 0.2 mm Infill - 20% Cubic Walls - 4 Top/Bottom layers - 3