LOFAR uses a large number of low-cost sensors (antennas, geophones and more) and relies on broad-band datalinks and advanced digital signal processing to implement the majority of its functionality in (embedded) software.

LOFAR will be the first large radio telescope system, wherein a huge amount of small sensors are used to achieve its sensitivity instead of a small number of big dishes.

The main reasons for this are:

• For the low frequencies involved in LOFAR traditional telescopes would be very large and hence costly.
• Pointing can be done electronically, without using move-able parts and hence saving on maintenance costs.
• It enables pointing in multiple directions at the same time.
• It provides operational flexibility (e.g. rapid switching between observations is possible).

From the LOFAR Site:
Her Majesty the Queen will open the largest radio telescope in the world, LOFAR, on Saturday afternoon 12 June 2010 in Borger-Odoorn (Drenthe). The new LOFAR telescope has been built according to a completely new concept. No large dishes are used, but large numbers of small antennas.

7,000 antennas are spread over 44 fields in the North of the Netherlands and from Sweden to France and from the UK to the East of Germany. Glass fibres connect the antennas with a supercomputer at the University of Groningen’s Computer Centre. In this way, a giant telescope is formed with a diameter of one hundred to one thousand kilometres.

The telescope researches, among other things, the earliest Universe, cosmic particles and magnetism in the Milky Way and other galaxies. LOFAR is also used for research in the area of geophysics, precision agriculture and ICT. While the antennas observe the sky, underground sensors collect date about the structure of the Earth. These data contribute to better models for the Earth, water management and gas exploitation. (source www.lofar.org)