AMRAAM FLIGHT TERMINATION ANTENNA DESIGN AND DEVELOPMENT

Abstract

This paper reports on the design of a B-band flight termination antenna (FTA) for use on the Advanced Medium Range Air to Air Missile (AMRAAM). The antenna is a low profile structure composed of an etched circuit board measuring 1.6 by 10.0 by 0.010 inches mounted inside a 0.17 inch deep cavity formed in the back of the AMRAAM harness cover. There is a metallic cover over the cavity which connects to the metalized harness cover constituting a ground plane for the antenna. The antenna is easily tuned through use of two metallic slugs in close proximity to the ends of the antenna elements. The active circuit of the antenna is composed of a 3-element folded dipole photoetched from copper clad Duroid. The center element is driven through a microstrip matching transformer which is printed on the opposite side of the antenna elements. A quarter wave open circuited stub is also printed opposite the elements to provide a virtual short such that no physical contacts are necessary between the transformer and the driven element. The matching transformer connects to the 50 ohm source at the center of the antenna through a side projecting microstrip tab which in turn is connected to a semi-rigid coaxial line. The antenna exhibits improved bandwidth and excellent pattern coverage, particularly in the critical roll plane. All of the antenna parameters will be presented and discussed.