Can You Work Amateur Radio on International Space Station with HF Antenna?

All of us amateur radio satellite operators know that the ideal setup needed to work through the cross band FM repeater on board the International Space Station is a directional Yagi antenna for VHF and UHF along with Doppler correction. While many operate outdoors with hand held radio, some operate indoors with azimuth-elevation antenna rotators tracking the path of the satellite. Some of us also have operated using vertical VHF only as well as dual band antennas with fair success. Some of us have been able to access VHF repeaters using 40m antennas, which prompted me to try satellite communication with my inverted V combination dipole for 40 and 10m. It has been mounted on a fibre glass pole at a height of around 33 feet from the ground, has a 1:1 balun at feedpoint and coax is 15m long RG 213.

Prior to the pass I checked the SWR using my cross needle SWR meter, using low power on my IC 2730 radio connected to the HF antenna. This video clip shows the reading taken three times to be around 1.7:1 for VHF frequency 145.990 MHz, the nominal uplink frequency for amateur radio on International Space Station. That was a reasonable SWR for short transmissions needed during LEO Satellite communications, especially as I usually do not call CQ, rather only replies to calls which I hear loud and clear.

Next I checked SWR on UHF frequency 437.800 MHz, the nominal downlink frequency of amateur radio on International Space Station, again on low power, with radio connected to HF antenna. SWR was around 1.3:1, quite acceptable for receiving fair signals on the downlink from ARISS which as a power output of about 5W.

Prior to the pass I also confirmed that the CTCSS tone on uplink has been set to 67 Hz. Sometimes the setting may be wrong if you have tried to access another satellite with a different setting previously.

This was the pass direction of the satellite as shown on N2YO.COM. It was a pass with about 60 degree maximum elevation from South West to North East. 40m elements of my antenna were roughly in East-West direction and 10m elements nearly perpendicular to it. As usual, I used the Argentinian Amsat pass prediction web page for manual Doppler tuning in my radio.

I was quite happy to hear VU3BGK several times during the pass using my HF antenna. I could establish two way contacts with VU3BGK through the FM repeater onboard the International Space Station comfortably using my HF antenna. In addition I could also hear VU3ZNL calling VU3BGK, loud and clear. Here is the recording of the relevant part of ARISS pass made with my mobile phone kept over the speaker of the radio.

This experiment establishes that there are more ways to work the FM repeater onboard the International Space Station, even though it is not the ideal way!