Telescopic antennas attached to RTL-SDR dongles tend to tip over. This mount holds them straight. The supplied .stl files match antenna diameters of 6 to 8 mm. Mounts with other diameters are easily obtained by modifying the supplied OpenSCAD file, see instructions below.

This is an alternative to or even an improvement over my previous designs
https://www.thingiverse.com/thing:6183925
https://www.thingiverse.com/thing:6057513

Printing requires support.

As always I include the OpenSCAD source file for you to adapt and/or improve:

• Download and install OpenSCAD from https://www.openscad.org
• Launch OpenSCAD and open the enclosed OpenSCAD source file (/File/Open).
• Amend the parameters at the top of the file or even amend the code.
• Save your changes (/File/Save).
• Render the design (/Design/Render).
• Export the rendered design e.g. as a .stl file (/File/Export/Export as STL).
• Slice and print.

See my other designs at
https://www.thingiverse.com/thinger13/designs