I heard we have a ham in space right now on the International Space Station so I built this 2 meter half wave loop antenna ("HALO" for short) to try and catch a few passes this afternoon.
I notched the 1/4" copper pipe for the 90 degree bend on the gamma match section, bent the 90 then soldered it closed and cut it to 2" x 5". I cut a 39 inch section for the loop and marked the exact center then bent it into a circle, bend the gamma match in a smaller arc. I used a piece of fiberglass rod from a broken fishing pole to bridge the 1-3/16" gap in the loop. I hogged holes on bottom of the 1/2" PVC pipe to solder connections through. Push the coax braid back and fish center conductor through braid. Twist and tin a 1/2" of braid and trim tinned braid to 1/4" long. drill a small hole in the bottom center line of loop to ease soldering the braid to center of loop. Strip the center conductor insulation to the appropriate length. Slide the prepared coax end into the PVC pipe, the braid will solder to the small hole you drilled in bottom center of loop and the coax center conductor will solder to the end of the gamma match.
I centered the resonance at 145.800 MHZ for voice and SSTV to and from the International Space Station. My gamma match is just shy of 2" x 5" and my ring is 39" with a 1 3/16" gap.
My first try yielded a near perfect VSWR on the target frequency! WOOT!
here is a great calculator:
home.comcast.ne...
I used 1 minute epoxy to fix the copper to PVC pipe and fiber rod.
I created a notch in both the bottom end of PVC pipe and PVC elbow for coax to exit before the PVC elbow connector.
I will seal all openings with RTV silicone to weather proof before roof mounting.
I can't wait for a few ISS passes!
Post your projects and comments!
Негізгі бет 2 meter "halo" half wave loop antenna for ISS SSTV & voice
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