Hi,
My background in in electronics engineering. I conduct satellite communications for the military. I have not read the entire document but from what has been posted it seems that you8 guys are trying to make a LEO (Low Earth Orbit) The neat thing about the one you are trying to make it is not going to fly in a vector or tangent to the earth. But it will just fall and I hope parachute back down to earth. Ok To address the issues of effetive communincation. When you are talking about LEO or any other type of satellite you have to use both (for this case) USB and LSB because you are only using one frequency. The neat thing is that all you have to do is add a "stereo" chip to the board so that it can pick up both USB and LSB use the USB to send info down. The LSB for uplink. Now the easy part, making the antenna from the weight restrictions and price, it sounds like I am going to have to go gehtto macgiver. Parabolic dish (Make it a CONE, or half a soccer ball shape since it is going to be broadcasting down it gives it a better footprint) make it our of either aluminium foil glued to a carboad backing 2 layers of BBQ aluminium foil should suffice or you can use the small valentines day metallic balloons cut a hole for the antenna and done (PS there are some cheap ballons that only half is metallic the other half is transparant plastic perfect for making the antenna just cut a hole put some silicone glue around it inflate it again(little gas not much) and you have a weather tight seal.) The antenna dimessions are for the makers of the satellite to figure out.. I hope this helps some the total cost not including the chip should be no more than 10 Dollars US For that part of the project. Sine you are going to be making LEO communications. I would assume that you have a ground station parabolic dish if not go to your nearest land fill and look for a satellite TV dish calculate the dishes focii and presto. Another great thing is that the dish is going to be tracked by GPS therefore eliminating the need of a beacon frequency. So all you have to do is point the dish in the appropriate direction have a spectrum analyzer hooked up to monitor signal strength for the actual frequecny and done. You should be able to have more than one character per second. You could actully stream live video on the way up. But the way down well with the high winds at those altitutes it will be a pretty hard to stay aligned with the signal of the satellite.
Please let me know if this info helps out.
SGT A.
