Crossed field antenna
From Wikipedia, the free encyclopedia
A Crossed field antenna is a new type of antenna for long and mediumwave broadcasting, which is claimed to have the same efficiency as a conventional antenna but only one-tenth the overall height. However, claims made for this efficiency by the antenna's inventors have not yet been proven by independent observers.
The physical structure of a crossed-field antenna comprises:
- A horizontal metal disc (or "D-plate") raised above and insulated from the ground plane;
- A vertical hollow metal cylinder (or "E-plate") of smaller diameter than the disc, which it is mounted concentrically above and insulated from;
- A metal lattice funnel (or "extended conical section") radiating above and outward from and connected to the top of the cylinder.
The antenna's operation is described extensively in its inventor's literature. An independent report by the IEEE suggests that the crossed field antenna is no more efficient than a conventional antenna design. Both of these documents contain highly technical language (see External links below).
MusicMann 279 plans to begin a longwave service to the British Isles using a crossed field antenna located on a custom-built offshore platform off the coast of the Isle of Man. The company currently gives its launch date as "early 2007", citing a dispute with the original antenna manufacturer as a reason for the latest delay. This has done little to ally critics' scepticism that the station will ever launch.
In a press release in November 2006, Isle of Man International Broadcasting plc (IMIB) announced that they would make no further payments to Kabbary Antenna Technology after the latter's failure to produce adequate documentation and make an antenna available for independent testing, and that they were considering how to recover a 50% deposit of £300,000 paid during 2005 for the antenna. IMIB state they have an alternative supplier for a crossed field antenna.
