Talk:Smart antenna

Smart antennas for ATSC (digital television) broadcasts
I can only find one model of smart TV antenna on the market, the Sylvania DTA-5000. How disappointing... are there truly no other models available? —Preceding unsigned comment added by 199.46.199.231 (talk) 20:06, 15 May 2008 (UTC)

What is MIMO? And how is it different from a smart antenna system?

A smart antenna is an antenna system that changes its physical parameters (e.g., radiation pattern) adaptively according to the changes of wireless channels. Diversity array is the example of a smart antenna or adaptive antenna array. It comprises a few antenna elements, normally installed at the receiver side. Signals received at these antenna elements are of independent fading process. Developing signals from these antenna output may exploit diversity freedom to counteract multipath fading.

Recently, this kind of diversity arrays are installed at both transmitter and receiver sides to construct a multiple-input multiple-output (MIMO) communication system. Multiple data streams are sent through multiple transmit antennas and received through multiple receive antennas. With sophisticated signal processing, it is possible to increase the stability of wireless transmission and information capacity in comparison with a single transmit antenna single receive antenna system, which is called a single-input single-output (SISO) system.

c.f. Scientific American, July 2003, --Smartantennas 11:02, 10 June 2006 (UTC)

Some notes on the DOA estimation chapter
- The article lists three subspace-based methods: MUSIC, ESPRIT and the Matrix Pencil method. It then states: "They involve finding a spatial spectrum of the antenna/sensor array, and calculating the DOA from the peaks of this spectrum." This, however, is only true for MUSIC. ESPRIT does not include such a peak search.

- The next sentence is also misleading: "MUSIC involves calculation of eigenvalues and eigenvectors of an autocorrelation matrix of the input vectors from the receiving antenna array." This is actually true for ALL the subspace-based methods and nothing typical about MUSIC.

- The following sentence: "These calculations are computationally intensive." I find this misleading again. So far, only subspace-based methods are mentioned and their main feature is the low computational complexity, comparing them to the alternative maximum likelihood approaches. For ESPRIT, all you need is one SVD and a pseudo inverse whereas ML methods require many iterations of some non-linear optimization algorithm.

- Final sentence in this chapter: "Matrix Pencil is very efficient in case of real time systems, and under the correlated sources." MUSIC and ESPRIT are just as efficient for correlated sources if proper preprocessing is applied, i.e., spatial smoothing.

Beamforming
- "Beamforming is a latest technology being used for various purposes." This sentence is ungrammatical and uninformative.

Subject Ttile
How does one change the Subject Title from "Smart antenna" to "Smart Antenna?" 67.235.95.28 (talk) 04:25, 5 May 2009 (UTC)
 * Move tab at the top, BUT, please don't. The current setup is appropriate by the Wikipedia standards. (John User:Jwy talk) 04:40, 5 May 2009 (UTC)

Software Defined Antenna
It seems that most Smart Antennas are usually conventional antennas being matched by electronically controlled matching networks or fed through controllable phase shifters under software control. Wouldn't this make them a "Smart antenna systems"? This may be splitting hairs, but if the "antenna" is the point of conversion from electrical energy to electromagnetic radiated energy doesn't it make the concept of a smart antenna seem a bit tedious. Then there are the Software defined antennas, an emerging class of smart antennas that are able to dynamically alter their physical structure to accomplish many of the effects of matching and beam steering at the point of conversion. Still under software control, the SDA might consist of an array of patch elements and a feed structure that morphs to vary the phasing, thus causing beam steering. By changing the patch size or orientation (again under software control) different frequencies and polarizations are also possible. Should their be a section added for SDAs? Sgemeny (talk) 17:36, 4 February 2010 (UTC)