D band IFF for army air defence systems

IFF, or identification friend and foe, is a well-established feature of military systems. However the in-service performance of the IFF fitted to earlier army air defence weapons has sometimes been far from satisfactory. Principally this was because of the difficulty of designing a suitable antenna to give the required performance when installed on a small armoured vehicle or man-portable missile launcher. Both configurations have physical dimensions which are small in terms of the wavelength, and installing antennas with even moderate gain has often been viewed as too difficult. However, as the instances of fratricide in the Gulf and in northern Iraq have shown, shortcomings in the implementation or use of IFF can have tragic consequences. This paper reviews some of the changes in the army air defence environment, and their impact on the design of D band IFF systems for army use. An IFF system simulation model has been used to aid in specifying the equipment and antenna requirements for small weapon platforms. The paper describes the main features of this model, and also novel antenna designs which enable better IFF performance to be obtained.