I worked on AO-40 satellite since mid August 2001 and find that it is more technician task from all I ever do before. I chose made my own antenna equipment than buy ready to go design , not so that it will be more cheaper , it very interesting too... In first You need a good s-band converter . Current AO-40 transmitter antenna has wide beam and not so strong on receiver side as expected. S-band signals is weak and sensitive converter extends Your ability to hear any signal from earth within passbands, receiver antennas on AO-40 instead has very good sense and collect many signals from earth surface. So , I planning to modify some of consumer product from wireless cable or MMDS TV industry to receive AO-40 signals s-band downlink . For help newcomer get started , I recommend to read this nice article about Phase IIID satellite. For russian language user please look here.
I suggest that compact round design will be more suitable for set in focus of prime or offset parabolic dish. I made some experiments and finally find that 0.8 m offset dish is the best for receive. Add transmitter antenna and You may try test on the air.
This simple setup on single horizon-horizon polar mount is very useful for AO-40 . About 315 QSO from 39 countries around the world was worked (but only 7 confirmed). For now, I made next improvement in uplink antenna design.
Home made 6 turn helix on 1m boom is better performer than I ever have. Simple programm was used to calculate helix dimensions . You can get it here. Construction is as easy as I can do, it was used water pipe from hardware store 5 sm in diameter and 1m6sm long to support structure and 2sm diam 18 sm long with litlle hole on the end to fix helix coil. Square screen 45x45 used for reflector. Note on disc directors on input side of S-band converter , vary this elements You can change diagram of Your converter to fit any F/D parabolic dish. I find experimentally that 7 elements formed good diagram for 0.7 F/D offset dish used in SAT TV antennas. Input feed of converter now looks like disc Yagi antenna , drawing schematic is here. Driving element was made for left hand circular polarization.
Here, test of my portable AO-40 ground station setup was made on nearest rocky mountaines about 40 km far from home qth.
More photos and more technical info will add later...
See You on the AO-40 !
73, Oleg EX8MLT