Bouncing Signals Off The Moon

One of the great things about ham radio is that isn’t just one hobby. Some people like to chit chat, some like to work foreign countries, some prepare for emergencies, and there are several space-related activities. There are hundreds of different kinds of activities to choose from. Just one is moonbounce, and [Ham Radio DX] decided to replicate a feat many hams have done over the years: communicate with someone far away by bouncing signals from the moon.

The set up is pretty sophisticated but not as bad as you might imagine. You can see that they spend a lot of time getting the equipment aligned. A known reference point helps them set the position of the antenna. A GPS keeps both stations in sync for frequency and time.

Some of the gear is repurposed commercial gear. A standard transceiver generates the signal, but not at 10 GHz. A transverter and a 60W amplifier put out a relatively strong signal at 10 GHz.

As far as we know, the first proposal for bouncing a signal off the moon came back in 1940. The military and a Hungarian group were the first to pull it off in early 1946. Remember, with no satellites, having a direct teletype link between Pearl Harbor and Washington DC was an amazing achievement.

Ham radio operators starting using moon bounce (sometimes called Earth Moon Earth or EME) back in 1953. The round trip propagation time is about 2.5 seconds or so. In this case the stations used WSJT, a computer program made for weak signal work.

The Hungarian effort back in the 40s was pretty interesting. 10 GHz is pretty high frequency. But there are always X-rays.

28 thoughts on “Bouncing Signals Off The Moon

  1. I’m shocked at how incomplete this article is. You don’t even mention the helium filled radio balloons high above the flat-Earth that store the entire RF spectrum for a short while and rebroadcast it so that it matches the round-trip reflection times that would be part of the orbiting moon – if not for the deep state conspiracy theory to keep the truth from all humanity. Shoddy reporting IMO.

    1. Hoax! Those balloons would float off forever, if they weren’t tethered. And nobody has ever found those tethers. Besides: how can you call it ‘deep’ state, while the Earth is flat? It’s ‘waf’ state. ‘widened-and-flattened’.

  2. HAM was why I got into electronics. Dad and other relatives were quite into it and started teaching me electronics about 2nd grade for what that was worth, it was all tubes and point to point wiring then, and got my interest by way of an electrifying experience trying to plug a reel to reel recorder into an extension cord. Scared and pissed me off such that had to learn and defeat this electrickery stuff. I liked the electronics but Ham was lacking as all you can do is communicate with people far away that talk strange. Uncle’s ham shack was a blast though… I wanted that teletype! Was present to see lots of EME and MARS being actively used but just wasn’t enough one COULD DO WITH IT other than communicate with MORE strange sounding people, and this is fun?. But did get to know electronics in depth before getting out of high school. Thankfully finally got my hands on an SPC 16/60 magnetic core computer… it needs no strange person on the other end so I was hyped and stuck with digital long time. But everything was getting tiny…

    Do get yourself a binocular microscope… you need as of 15 yrs ago. Best of luck! Wonderful hobby, great career.

    1. The reason I got into electronics when I was a kid was a family friend who had polio designed and built his 80 meter transmitter. Friends had constructed a half wave dipole antenna with telephone pole end supports and connected the farm’s water well as a ground. He could reliably key the mic, say CQ CQ CQ, W0QQT, unkey the mic and hear the signal on his receiver delayed by the distance as the signal went fully around the earth. I still think that is pretty cool. And I think it was really cool that a disabled person could study, learn, design and build this system literally from scratch, individual parts ordered and purchased through the snail mail (actually they used to do that before the internet).

      Being able to reflect a signal off the 90% absorptive basalt on the moon and receive it on Earth is also one of these.
      It’s a shame that with the times we’ve visited the moon that we didn’t put up a solar powered Ham transponder there. Even a 1 watt transponder would tremendously increase the ease of moonbounce.

  3. Quote: Ham radio operators starting using moon bounce (sometimes called Earth Moon Earth or EME) back in 1953. The round trip propagation time is about 2.5 seconds or so. In this case the stations used WSJT, a computer program made for weak signal work.

    That paragraph needs to be rewritten. By running then and now together, it seems to suggest that hams were using WSJT back in 1953, when the number of computers in the world was probably in the double-digits.

    Timing is very important in weak-signal communication using software. I assume that WSJT takes that into account in EME communication.

  4. “10 GHz is [a] pretty high frequency.”

    10 GHz is in the “Super High Frequency” (SHF) X-Band. The X-Band frequency range is specified by the IEEE as 8.0–12.0 GHz. Ref:

    But IMO that’s not so high. How about 3 THz in the 300 GHz – 3 THz “Tremendously High Frequency” (THF) band! The THF band is so high in frequency it doesn’t even have an IEEE letter designation (yet). Now that’s what I call “pretty high”. Ref:

  5. de KC1CCG — Isn’t moon bounce radar? which is contrary to the rules. A shame since radar would be quite interesting with components available now. If only the operator of the transmitter hears the return (ie not a QSO)….isn’t it radar?

  6. My father, Bill Duval K5UGM did moon bounce. When I was 13 years old we spent all weekend constructing the dish and using his transmitter we succeeded, then subsequently knocked out every TV in the neighborhood.
    He died in 2006 and I miss him every day. Only recently have I tried to document his accomplishments.
    He was an amazing man and one hell of a ham radio operator.

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