KA-Sat starts emitting in KA-Band


Welcome to our new Café! After a redesign the NewConceptsCafé opens again!

Since the Café was opened, one of the most clicked posts has been the one referred to the KASAT emitting in KA-Band. Well, it started to work successfully ten days ago as I discovered reading one of my favourite blogs: GIZMAG.
Currently I’m working in a new Ka-Band satellite so I can imagine the difficulty of this design.I’ll try to explain easily how it’s made and how it works.

The satellites usually flight inside a launcher. Depending of its weight and size it will flight in a different one.
The most used are:

- The Ariane 5

- The Proton

- The Soyuz

The satellite goes inside the top part of the rocket as payload and obviously it must fit inside. That’s the reason why everything is folded.

HERE you can find some interesting images.

There are two different efforts that a satellite must hold. The launching and the thermal efforts once is placed in orbit.

The first one is mainly induced by the vibrations of the launcher engines. It can reach values over 100 G in some parts.

Once the satellite is in orbit, the gravity and the centrifugal forces are equilibrated and so it does not feel any gravitational effort. But its new enemy is the sun. The difference between a radiated and no radiated part can go from -180 to 180 degrees. That means extreme parts solicitations by dilatation. That’s the reason why satellites are covered by a sunshield. This sunshield prevents from direct sun exposure but also keeps radiation rebounding inside heating more equally the different parts. There is a minor thermal gradient. It’s important to add that the sheet that works as sunshield must be transparent to the frequencies that the satellite uses to emit and receive. In this case, as a Ka-Band satellite these frequencies are: 26.5 to 40 GHz

Before deploying all the reflectors and the solar panels are clamped to the satellite body to avoid bad behaviours and cracks during the launch.

The most used mechanism to detach the parts from the satellite are the pironuts. Pironuts are explosive nuts that. Once they explode they release the extra clamps letting the ADPMs (Antenna Deployment and Pointing Mechanism) motors drive reflectors and solar panels to its final position in the satellite flight configuration. Now, the ADPMs and the satellite attitude control work together to reach the correct pointing to targets on earth.

The KA-Sat it’s a multi-spotbeam satellite so it must point to all the coloured circles you see in the picture. This means a little metallic horn pointing to a main reflector to rebound and amplify the signal. In this case it has 82 horns (quite a lot). The horns are really close to each others as you can see in the picture (are the white cup-shaped parts you can see in the top of the satellite in the picture below) In this case it seems that there are four arrays, 2 per reflector.

The complexity of the parts to produce and assemble can only be intuited by looking a this part that can represent a 1% of the total satellite systems.

So happily we have our new satellite emitting and allowing the not ADSL covered zones to reach a good transfer speed in their internet conections.

And of course giving extra tools to SKYNET to control us :-)

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