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*Subject*: UoSAT antenna pattern?*From*: Chris Hill <CRH_Telnet@xxxxxxxxxxx>*Date*: Sun, 26 Apr 1998 23:23:48 +0800

Hi, Can anyone do better than this? I am trying to model the radiation pattern from the UoSAT (eg UO-22, KO-23, KO-25 etc) satellites on the 70cm downlink. Unless anyone can do better, I'm going to use; Radiation Intensity F(theta) = ( sin(theta) ) ^3 i.e the sin of theta all raised to the third power, where theta is the angle of radiation away from the z-axis. This equation gives a null straight through the z-axis (the radiating element being along that axis), and a maximum at 90 degrees, which means a maximum straight toward the horizon (assuming the satellite always has it's z-axis pointing towards the centre of the earth, which it does). The -3dB beamwidth works out to about 54 degrees, which is about right for a halfwave dipole. Also, in the program that uses this, I am proposing to put a 12dB ceiling on the loss of signal straight along the z-axis, as this reflects the worst case loss I have seen when looking straight up into the -z axis of the satellite on direct overhead passes... any comments on whether 12dB is a suitable figure? 73 Chris VK6KCH +-------------------------------------------------+ | Chris Hill email : vk6kch@amsat.org | | CRH Telnet PTY LTD A.C.N. 008 922 530 | | Phone : +61 8 9354 8416 Fax : +61 8 9354 8826 | +-------------------------------------------------+

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