AJE Aerial

Aerial Outfit AJE

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General Description

The AJE, known to sailors as the "Christmas Tree", is an omni-directional aerial system for the frequency range 225-400 MHz.

Following the Atlantic City Conference in 1947 when the frequency group 200-420 MHz was allocated for short distance mobile communication the requirement arose for the development of an aerial system covering most of this range for H.M. ships.

A paper was presented to the I.E.E. (UK) entitled "The Design of an Omni-Directional Aerial System for the Frequency Range 225-400 MHz" by F.A. Kitchen B.Sc. on 6th April, 1951 and was subsequently published in Vol 98, Part 3 No 56 November 1951 of the Proceedings. This paper describes the development of the AJE aerial in much detail.

Technical Data

The AJE is described as being a simple communication aerial system having adequate performance in respect of both the normal radiation diagram characteristics and terminal impedance variations. The aerial has nominal 75 ohms impedance and is normally vertically polarized. The aerial is suitable for attaching directly to unbalanced feeders.

Later literature describes the aerial as being a broadband quarter wave monopole.

A later version uses a solid metal shroud for both upper and lower radials, rather than the bird cage type construction. (AJE(5))

It was not unusual for these aerials to be mounted pedestal to pedestal, the bottom one being inverted, with an assembly being placed at each end of the yardarm.

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© Ian O'Toole, 2009. Page created: 28/04/03 Last updated: 27/10/2012