Chasing Cubesats on a $25 Budget with an RTL-SDR and Homemade Antenna
Cubesats are small shoebox sized satellites that are usually designed by universities or amateur radio organizations for basic space experiments or amateur radio communications. Typically they have an orbit lifespan of only 3-6 months.
Cubesats typically transmit signals at around 435 MHz, and they are powerful enough to be received with a simple home made antenna and an RTL-SDR. To help with this Thomas N1SPY has created a YouTube video where he shows exactly how to construct a cheap eggbeater antenna made out of a few pieces of copper wire and an SO-239 UHF connector. Later in the video he demonstrates some Cubesats being received with his antenna, an RTL-SDR and the SDR-Console V3 software.
2018: Thomas N1SPY chases mini satellites on a budget
AOBA-Velox, VZlusat2, Horyu IV, and LUSAT (Oscar 19) are pretty powerful transmitters.
You can literally build yourself a dipole or a vertical using an online calculator.
Just getting the right length of copper for, say, 435mhz would help a great deal, and cost virtually nothing.
The antenna-set that’s available in the RTL-SDR shop will also work as a dipole, just squash the telescopic legs in until it’s the right length for your desired frequency.
Good luck, and don’t hesitate if you’ve got any questions.
By using “orbitron” (satellite tracking software) and “SDR#” (the software that connects to the radio), along with a few plugins for SDR#, you can track the satelites using orbitron, and that will tell SDR# which frequency to tune to accounting for doppler shift. Try looking on this page here and about 1/3 of the way down it starts talking about orbitron etc…, you might find this useful for these cubesats as they seem to need a huge constant change for Doppler Shift!
Alex, Yes, Orbitron works great! I wonder if anyone has found a way to have it tune a radio and direct an antenna rotor, for a directional antenna, at the same time?
Seems that with this software, I can only do one or the other, so it’s a bit of a puzzle.
Great video Thomas.
Last week a fellow ham and I listened in to one of these satellites passing overhead. We set up two different 2m radios and two different antennas; one radio using a J pole on a tripod at ground level, the other connected to a discone on the roof. Several minutes of QSOs were heard.
Now it’s time to try listening in with a RTL-SDR.com dongle. What’s nice about that is that you can track the satellite’s signal as it passes via the waterfall.
QST also has an article about cubesats in the latest issue.
The eggbeater looks like a fun project. I luckily managed to pick up some of the stronger amateur radio sats with only a 12 inch clip-lead hanging off my rain-guttering, from the stub of a DTV (4.5 inch “vertical”) antenna included free with many SDR dongles. Just clip a lead onto the stub of the DTV antenna, and wait for a strong one to pass, and you should get something on the beacon frequency.
I now have a dedicated mobile 70cm/2M vertical, but have been wanting a QFH (or eggbeater) to get better coverage. Even with the vertical, some strong beacons are clear down to 10-15 degrees.
Next challenge would be to demodulate some of their digipeater or telemetry signals!
@Joe said: “I luckily managed to pick up some of the stronger amateur radio sats with only a 12 inch clip-lead hanging off my rain-guttering…”
Hi Joe, which satellites specifically were the “stronger” amateur radio satellites? I would like to give this a try, but finding which satellites are “strong” enough for a clip-lead approach looks like a difficult task. Thanks – Me