Bettering Low-cost SDR Antennas | Hackaday
[VK3YE] knows that the cheap antennas you get with most SDR dongles have at least two things wrong with them. First, they are too short. You want enough to pull out a quarter wavelength on the longest frequency you want to run. The second problem is that there is no real floor. He fixed both of these issues as you can see in the video below.
The result might be called an ugly duckling rather than a rubber ducky. But it seems to be working. You could probably come up with something nicer to reseal the base, but the tape works. A nice 3D printed case would work too and improve the appearance. We also thought of the goop that you use on tool handles.
We just cut these antennas off and reused the cable and connector to plug in a better antenna. You can get more miles with this approach. On the other hand, the magnetic base and relatively small form factor is pretty attractive.
If you want to do this before and after testing, we recommend using Python. Or just bite the bullet and build something that looks like it should be in a movie.