Crossed field antenna

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A crossed field antenna, or CFA, was a type of antenna for long and mediumwave broadcasting, patented in 1986, which was claimed to have the same efficiency as a conventional antenna but only one-tenth the overall height. The invention was received with incredulity from experts in electromagnetics and antenna technology owing to the deficient theoretical justifications offered and the lack of viable experimental verification.

The physical structure of a crossed-field antenna is:

  • 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 in its inventor's literature. An independent report by the Institute of Electrical and Electronics Engineers (IEEE) suggested that the Crossed Field Antenna was no more efficient than a conventional antenna design of the same height (see External links below).

The Isle of Man International Broadcasting Company (IMIB) planned to begin a long-wave service under the name Musicmann 279 using a Crossed Field Antenna located in Ramsey Bay off the coast of the Isle of Man. However the company stated in November 2006 that it was in dispute with the antenna supplier KAT over non-delivery of the antenna and recovery of a £300,000 deposit. The company's web sites disappeared in October 2007.

There is a handful of CFAs operating in Egypt, at powers ranging from 1 kW to 100 kW. These have been operational for over ten years and were developed by the engineering sector of the ERTU the Egyptian state broadcaster for their own use. Many CFA projects in other countries failed including those in Australia, Brazil, China, Germany, Italy and the UK.[1]

At the General Assembly of the DRM Consortium in Hangzhou China in April 2004, a Chinese manufacturer Zhongli made a demonstration with assistance from Thales SA and fed their new Crossed Field Antenna with 6kW of DRM power. (RadioNews Issue15 Spring2004). Results of the test are unavailable and no other CFA projects have been announced in the last six years.

[edit] References

  1. ^ Stone, J.L. (2006). "Whatever Happened to the commercial CFA?". Antennex. http://www.antennex.com/Stones/st0806/ant_prop.html#whatever_happened. Retrieved on 2008-02-05. 

[edit] External links


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