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Never heard of that before and I thought you were joking, as the moon is such a small percentage of the earth’s sky and on top of that it is spherical and only a small portion of it’s surface will reflect back to earth. I’ve heard of bouncing skip off the ionosphere, but what kind of precise wave propagation would you need to actually bounce a signal off the moon at a specific spot over the horizon?

No joke. Generally, you use morse code and you send just your call sign due to the signal being so faint.

Also, keep in mind that you can’t use HF and a lot of power (1500W is the limit). You have to use VHF, which is 50W max. VHF because it can leave the ionosphere, hit the Moon, and bounce back again. Actually, you’d like use UHF (70 cm band)

Never heard of that before and I thought you were joking, as the moon is such a small percentage of the earth’s sky and on top of that it is spherical and only a small portion of it’s surface will reflect back to earth. I’ve heard of bouncing skip off the ionosphere, but what kind of precise wave propagation would you need to actually bounce a signal off the moon at a specific spot over the horizon?

It is indeed true - I am not quite ready to test it out, but I am building a "small" ham radio moonbounce antenna array that I hope to have functioning by summertime. I haven't done the complete link budget calculations yet, but stations smaller than what I'm putting together routinely bounce signals off of the moon and handle two-way communication with the moon reflecting their signals to distant locations that otherwise would be out of radio range for UHF signals.

I'm planning to use the 432 MHz band, and the antenna array that I am building will consist of four 22-element yagi beams, each antenna having a boom length of close to 15 feet (a single antenna gives almost 18 decibels of gain, and each additional antenna in the array incrementally raises the total achievable gain, if they are spaced and phased correctly), with all four mounted on an "H frame" so that they can all be aimed skyward in sync in the same direction, via an azimuth rotator and a separate elevation rotator.

Radio-wise I am currently planning to use at least 100 watts directly at the antenna power-divider feedpoint, but would like to go to 500 watts or even 1000 watts if I can afford it. These days, ham moonbounce stations typically use a digital radio transmission mode called JT65 which permits digging weak signals out of the background noise.