Hello, I'm planning a HAB, and for that I choose the RADIOMETRIX - NTX2-434.650-10 - TRANSMITTER, 434.65MHZ, 10MW
the balloon wil be 30 km from earth and sending messages RTTY to my ICOM-IC R20 in ssb mode 70cm. but I dont know what antenna to use for the balloon, neither for the ICOM IC-R20.
Can you please help me?
Thanks, Daniel
Daniel, The type of antenna depends whether you are able to direct the antenna. If the balloon is high above the earth, the antenna should be underneath the balloon, looking to the earth. A simple dipole antenna can be made from coaxial cable with the shield folded back. Both the folded back part of the shield and the free part of the inner conductor a quarter wavelength long. This antenna can be made weatherproof with shrinking sleeve. See drawing. This antenna can be used hanging underneath the balloon. At the ground you could use a yagi antenna if someone is available to direct the antenna to the balloon. Otherwise an omnidirectional antenna must be used. 10 mW is not much power, but with a free line of sight you can cover long distances. Johan PA0JBB
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