70cm Yagi Antenna with SDR

Simple & lightweight Yagi antenna for the 70cm band. Developed in conjunction with the ‘Touch The Universe’ project.

Required hardware

• 3.2mm aluminium welding rods
• 4mm brass welding rod
• 25mm PVC pipe
• ~3mm self-tapping screws
• superglue / silicone / hot glue gun (optional)
• soldering iron & solder
• SMA edge connector (Aliexpress)
• SMA PCB adapter (can be ordered from JLCPCB for $2 - see provided gerber files)
• RTL SDR (Aliexpress)
• USB-A extension cord (~2m)
• cable ties

Printing instructions

Works best with PETG or similar. I recommend default 0.2h@0.4n presets. Add more perimeters for extra strength (optional). No supports required.

Assembly instructions

• cut the welding rods to size (see the provided drawing for dimensions)
  • the 4mm brass rod needs to be cut 2mm shorter and split in half to account for the center gap
  • roughen up the ends of the brass rod with a file or sandpaper for easier soldering later
  • file / deburr all edges
• mark the centerpoint of each aluminium element and insert each one into the appropriate printed part
  • use the top hole to align the center mark, then fill the hole with glue (optional)
• solder the SMA connector to the SMA PCB
• insert the brass elements into the 'Z' printed part and solder the PCB to them
• cut a ≥70cm section of PVC pipe and mark element locations (see the provided drawing for dimensions)
• attach the elements to the PVC pipe
  • make sure the pointy holes on the sides of the printed parts are facing towards the business end of the antenna
  • secure them by running a self-tapping screw through the hole on the bottom of each printed part
• attach the SDR using the SMA connector and secure it to the 'S' printed part using a cable tie
• connect the USB extension cord and secure it to the 'R' printed part using a cable tie