In January this year iSat Networks (iSat) was awarded a contract by ESA to develop a feed adjustment mechanism, with both manual and motorised operation, to provide improved alignment of Ka-band VSAT antennas and tracking of inclined-orbit satellites up to ~±3° in the C, X- and Ku-bands. The inclined system reduces the costs of using inclined capacity.
Result of Ka band manually feed development
Figure 1 Illustration of the manually adjusted feed mechanism currently under development
The Ka-band adjustable feed development will provide enhanced RF performance for Ka-band antenna systems and facilitate easier installation by less skilled installers. The unit is available with or without a rear mount BUC bracket which reduces waveguide loss.
Preliminary Results for inclined tracking
The C, X- and Ku-band motorised feed development will provide a simple retrofit solution to enable the tracking of inclined orbit satellites at a substantially lower cost than currently available Az-El tracking systems.
iSat has carried out initial tests of the motorised feed using a 1.8 m offset antenna at Ku-band (11.45 GHz) tracking the beacon on NSS-7 which is operating in a 1° inclined orbit. The tests were conducted at our facility in Cody Technology Park, Farnborough.
The antenna gain pattern is shown below – note a >20dB loss for a 1° mis-point.
The next plot shows the beacon level at the receiver with no feed tracking – in fact the beacon signal is completely lost due to carrier being in the noise, as the satellite oscillates in its inclined orbit
The final plot below shows the beacon level at the receiver when the iSat feed tracking is enabled. The plot shows the feed position alongside the beacon level which remains steady (<1dB variation) and shows no loss of signal associated with the tracking.
The work continues at iSat, and anyone interested can contact us now for more information.