Homebrewing Dual Band Moxon Yagi for LEO Satellite Operations

| September 24, 2023 | Amateur Radio (Ham Radio), Amateur Radio from International Space Station, Amateur Radio Satellites, Antenna and Propagation | No Comments

Homebrewing Dual Band Moxon Yagi for LEO Satellite Operations

I have been using a vertical omnidirectional VHF antenna for working through the voice transponders of Low Earth Orbit (LEO) Amateur Radio Satellites, with limited success. I have been able to work through International Space Station, Tevel Series of satellites and occasionally AO-91. Ideal way to work LEO satellites is using cross Yagi for VHF and UHF having facility for tracking azimuth and elevation as the satellites moved very fast across the sky. But I have only one radio and no diplexer suitable for a base station, to connect two antennas to one radio. I had homebrewed a seven element VHF Yagi and a five element UHF Yagi earlier. So I had surplus 3/8 inch aluminium pipes with me. I found a design for Moxon Yagi by M1GEO/G8OCV on the web. I thought it will be ideal for use with my single radio, though I still need a method of tracking the satellite movement.

I have been having this project in mind for quite some time, but was hesitant to go for it as the description was using 3.2 mm aluminium welding wire, which I did not have. I was wondering how I could bend the aluminum pipe for the Moxon elements, if I were to use the surplus aluminium pipes available with me. Though different methods were advised by my friends, there were limitations. Finally I decided to go for the simple manual bending method, though it would produce flattening of the pipe at the bend region. Dual band Yagi design was such that the VHF Moxon driven element would passively couple with UHF elements. So only one feeder is needed, unlike in usual dual band Yagis. I measured out the elements according to the design and cut them using a Hack Saw. Next I had to bend the Moxon elements to make a rectangular shape as per the design manually. Next step would be to fix them to wooden boom as suggested in the design. As I could not find a wooden boom at home, I decided to use a surplus PVC pipe in the store. Planning to do it the next day, with a fresh mind!