The Crossed Field Antenna (CFA) is one of the applications of Maxwell's law ,
which shows that the source of the Magnetic Field is only the Displacement
Current ; not the Conduction Current.
EM Theory Corrections were applied carefully to produce the new CFA antenna in 1986 ,Scotland , developed in Egypt 1989 for high power , by Egyptian antenna group ( Dr. Kabbary Group ) , where many High power CFAs were used in ERTU radio stations since 1989 till now , after replacing mast antennas and also for new projects.
The New Correct Antenna Theory could show that the size and efficiency of the CFA antenna don't depend on the wavelength.
From our new antenna theory, one can realize that the dynamic reactions of the two fields E and H occur in in the Near field , where E is produced from the Cylinder and H is generated from the Disc.
This new CFA device was discovered by both Prof. Maurice Hately , a well-known electrical engineer now resident in Scotland, and by Dr. Fathi Kabbary , The CFA was developed for HF commercial products since 1987 in the UK, with the help of the brilliant Physicist Dr. Brian Stewart from Strathclyde University of Glasgow.
Dr. Kabbary had moved back to Egypt, in early 1990s developing the CFA for high power , where the first high power 60 kW CFA 1161 kHz , had been installed in Tanta Radio Station , running for 4 years till the modified CFA version with Upper Cone in 1994 to turn sky wave into ground wave resulting into higher gain , reaching a very low profile antenna . This was the turn over point to put the CFA into regular daily service since 1994 till now, where the power was reduced to 30 kW to avoid the interference with other stations, as Alexandria radio station 1197 kHz , 25 kW , in day time .
The CFA has many other advantages
(see CFA Advantages page) in addition to its small size.
The antenna stays in tune and does not require constant adjustment - Some Radio
Engineers will be pleased to hear, as their station bosses invariably make them
carry out such re-adjustments at unusual times (such as 4 am Monday morning,
when it is hoped hope few listeners will be trying to hear their favorite
One of the best features of the CFA however is that it has a much reduced induction field around it. A traditional or resonant antenna sets up a fierce voltage close to it which is induced into neighboring metals and other transmission lines, (such as those for electrical power and telephones, etc.) often manifesting itself as interference to telephones at best, and as a nasty shock for anyone who touches the lines at worst. With the CFA, the induction field is drastically reduced so as to be almost non-existent.
The low height of the CFA is just one of its advantages. The CFA could be operated as simply a drum above a disc, and the original models were developed from this.
The conical structure on top of the cylindrical section is a Sky Wave Depressor , which causes sky wave components to be depressed or deflected towards the horizon and be added to the ground wave, effectively giving the CFA ground wave of higher gain over that produced by a standard resonant vertical quarter wave antenna.
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