Testing the Moxon Yagi for Amateur Radio Satellite Contacts
Testing the Moxon Yagi for Amateur Radio Satellite Contacts
Recently I had homebrewed a Moxon Yagi for improving my setup for working amateur radio satellites. As I do not have a diplexer suitable for using with base station, Moxon Yagi is ideal as it has only one feedline. The VHF Moxon driven element couples passively with the 5 element UHF Yagi, which does not have a driven element. As I do not have an azimuth elevation antenna rotator which is also quite expensive, my friend told me to keep the antenna pointing towards the direction of the maximum Elevation Azimuth. In this way, it would cover almost 4 minutes of a satellite pass, which is good enough for me.
From the Amsat webpage I noted that the upcoming International Space Station pass has a maximum elevation of 45 degrees. The corresponding azimuth was 226 degrees. I used the compass on the Heavens Above app to set the antenna direction prior to the pass and waited for the satellite pass. I set my dual band dual VFO full duplex radio for manual Doppler tuning as displayed live on the Argentinian Amsat webpage which I use for all my satellite work. I could see that the maximum elevation azimuth displayed there was same as the one which I had set. Two stations were received very well on the setup, but I could not access the repeater!
On the previous day, I could hear several stations well on a higher elevation pass with the same antenna. Yet I could contact only a couple of them. But at that time, I had pointed the antenna towards the beginning of the pass, hoping to copy long distance stations with the new setup. Of course, the first station which I heard was one from nearly 1350 km and I was quite happy, though I could not work that station.
Next pass available was Tevel 3 with maximum elevation 45 degrees. Azimuth at maximum elevation was 122 degrees. I rotated the antenna to the new direction and came back and checked the SWR. To my surprise, it had shot up. I presume that there is some loose contact in the system. I quickly switched to the vertical antenna and could have a contact with one station, with difficulty. I could gather that more work has to be done on fine tuning the Moxon Yagi setup!