Satellite beams and dish sizes

A Satellite's Beam is also known as a footprint. What is a footprint?

A footprint or satellite beam is the area on the surface of the Earth covered by the microwave radiation from a transponder. The position of a satellite footprint depends on the orbital position of the satellite, for example Eutelsat 36B's footprint is meant for Africa and Europe and so cannot even reach America because of the shape of the earth. A single satellite can have many footprints because satellites have many transponders.

In a nutshell the footprint shows the area that a certain satellite can be received or cannot be received. Satellite footprints are usually drawn on a map with a contour like drawing showing different areas in different colours to emulate the strength of the transponder signal.

Some footprints have the satellite power written on the contours and also show the required dish size to receive a certain satellite transponder(s). There are some websites where you can get satellite footprints with the most common being lyngsat.com and satstar.net.

With the help of a few screen clips I will show you how to interpret satellite footprints. Do you remember the last screen clipping from lyngsat for beginners?. This is a continuation from that post. By now you that the second last column gives the beam information. Take a look at the image below from lyngsat SES 5 satellite package. It shows only one transponder frequency 12015 V 29950. This is also the satellite that hosts the Zuku pay TV package.

SES 5 package

If you click on the Sub Sahara Africa link you will get the SES 5 Sub Saharan Africa beam on lyngsat. Alternatively you can visit the website satstar.net and click on Footprints. You will get a list of satellites with their orbital positions, trace the SES 5 satellite at 5 degrees East and click on it. You will get the following:-

SES 5 C band and Ku band footprints

 

Notice the four footprints: we are interested in the Ku band footprints so we concentrate on the Sub Saharan and Nordic footprints. But take a look at the Nordic footprint, it is pointed at Northern Europe so its not receivable to a person in Sub Sahara Africa. All channels listed on lyngsat with the footprint Nordic are therefore not receivable. Click on the Sub Sahara Africa Ku band image.

Now this is a satellite that is receivable in Kenya and notice that satstar.net gives you the estimated dish size required to receive the satellite signal. Around Kenya the EIRP is about 47dBW. A quick look at the table shows that the Dish size estimate for 47dBW is a maximum dish size of 85cm and minimum dish size of 65cm. In Kenya it is receivable using a 65cm dish, the size that Zuku Satellite TV sells.

Stronger signals require small size dishes while weaker signals require big size dishes.

With this information you can now start searching for other satellites receivable (with the appropriate dish size) in Kenya.

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Written by Gichane
Monday, March 16, 2014