Antenna Arrays Could Replace Satellite TV Dishes

Zothecula writes "There was a time not so very long ago when people who wanted satellite TV or radio required dishes several feet across. Those have since been replaced by today's compact dishes, but now it looks like even those might be on the road to obsolescence. A recent PhD graduate from The Netherlands' University of Twente has designed a microchip that allows for a grid array of almost-flat antennae to receive satellite signals."

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Array info

[Caerdwyn]

A collection of links on antenna arrays at a ham radio antenna design site: http://www.dxzone.com/catalog/Antennas/Array/

It's not all about signal strength. Sensitivity these days is rarely an issue; the electronics in the receiver are excellent. Of greater relevance are polarization, rejection of off-axis noise, directivity, and the ability to reject signals from adjacent bands. There are also issues of setup difficulty, and this is what the primary focus of the design in question is.

Aiming a dish antenna is a chore, and high winds which shake a parabolic dish can cause signal strength to fluctuate dramatically. An electronically controlled phased array can, by introducing delays to various antenna elements, "steer" itself and lock onto a satellite with great accuracy (within a few degrees of the direction the array is aimed). A small antenna, perfectly aimed, will outperform a larger antenna poorly aimed, and if the antenna's controller can aim itself without physical adjustments many thousands of times per second, wind and a... coarse job of aiming the antenna are non-factors.

A military example: PAVE-PAWS, a 435Mhz missile detection array used by the US Air Force. The antennas in question are made of thousands of smaller elements (a single dipole element at 435MHz is about 35cm long), do not move, but the transmitted radar beam and the reception-aiming can be extremely precise. The more elements you have, the narrower the beam but the higher the gain.

L-band, commonly used by companies like satellite TV providers, is 1 to 2 GHz. An array of 16 log-periodic (wideband) antenna elements would therefore be 60cm square. A 4-element array would be 30cm square. Pretty compact, and if it gets rid of the most common cause of poor signal strength (a poorly-aimed dish), it's a win.