21.04.2013 Views

ETTC'2003 - SEE

ETTC'2003 - SEE

ETTC'2003 - SEE

SHOW MORE
SHOW LESS

You also want an ePaper? Increase the reach of your titles

YUMPU automatically turns print PDFs into web optimized ePapers that Google loves.

2.2 Limitation of conventional Gain flatness Measurement method<br />

IOT gain flatness measurements are historically performed using a continuous<br />

sweep of the bandwidth without controlling the variation of the reference point.<br />

This method doesn’t take into account the variations of the measurements<br />

conditions such as temperature of the RF chain, antennas gain slope combined<br />

with satellite motion, propagation through the atmosphere fluctuations.<br />

The Figure 1 and Figure 2 are representative of obtained previous IOT<br />

measurements done on several satellites: all tests results are tilted leftward.<br />

The Figure 3 present a comparison between the ground test result during<br />

ambient phase (Reference test) and the result obtain during IOT (In Orbit Test)<br />

phase.<br />

Relative Level (dB)<br />

Comparative result AIT ambient / IOT conventional method<br />

1<br />

0,5<br />

0<br />

-2 -1,5 -1 -0,5 0 0,5 1 1,5 2<br />

-0,5<br />

-1<br />

-1,5<br />

-2<br />

Freq offset (MHz)<br />

-4-<br />

Relative level ambient result<br />

relative level IOT<br />

Figure 3 comparative result ambient ground test with In Orbit Test conventional<br />

method

Hooray! Your file is uploaded and ready to be published.

Saved successfully!

Ooh no, something went wrong!