footprint

The term footprint is used in a wide variety of contexts. For example, in satellite communications for the footprint of a geographical area, in storage technology for the subdivision of a RAM, in printed circuit board technology for the footprint of a component, and in digital communications technology for the trace left by the user in the network.

1. In satellite communications, the footprint of a news satellite on the earth's surface is the geographic area where a television or radio program is broadcast at a given transmission power. The footprint is limited by the outline of the geographical area with a specified radiated power( dBW). The size of the antenna required in the footprint is often specified. Large footprints with relatively low radiated power are called global beams, small footprints with high radiated power are called spot beams.
   

   Footprint of Astra satellite 1C with different antenna sizes. Graphic: ASTRA

2. In chip technology, a footprint refers to the dimensions of the packages and the space they require on the printed circuit board. While footprints of packages of central processing units, graphics processors and memory chips can be 10 or more square centimeters, footprints of small packages are a few square millimeters.
3. For printed circuit boards, the footprint represents the outline of a passive or active electronic component, integrated circuit( IC) or microprocessor on the board. The footprint, also known as a land pattern, is specified in length and width dimensions. Footprints of microprocessors are up to 50 cm2 in size, whereas the smallest footprints of chips are less than one square millimeter. The trend towards smaller footprints goes hand in hand with the trend towards smaller mobile devices.
4. The term footprint is also used in attacks on computers, programs and applications. In this context, it is a pattern that the attacker leaves behind with his unauthorized access attempts. This footprint can be stored and used to increase security.
5. One speaks of a digital footprint or data shadow when one leaves a trace while surfing the net. This can lead through social networks, across websites, web pages, blogs and chats. On all services and websites that are accessed, visitors leave a trace, which is referred to as a digital footprint. Demographic and geographical data can be derived from this information using appropriate algorithms, and user behavior can be analyzed.