A conformal UHF antenna suitable for satellite communications by small air, land & sea sensor platforms

Today\´s warfighter has access to seamless global connectivity through a number of satellite communication (SATCOM) networks operating at frequencies from UHF to K band. This is especially important when performing Intelligence, Surveillance and Reconnaissance (ISR) missions with an Unmanned Air Vehicle (UAV) where a pilot may be thousands of miles removed from the platform. A very attractive radio link to a mobile ISR platform is provided by UHF SATCOM, which requires only modest gain antennas. However, the small physical payload size and weight requirements of new and evolving ISR platforms present a significant challenge to the antenna designer where efficiency and bandwidth must be traded with antenna size. JEM Engineering has developed a new UHF SATCOM antenna design that utilizes advances in realizing magneto-dielectric (MD) substrates for a spiral radiator. Considering the gain-versus-frequency curve for spiral antennas, JEM\´s advanced MD substrate reduces the size of the spiral needed to achieve a useful low frequency “knee”. An Artificial Magnetic Conductor (AMC) is also used in the spiral cavity to recover energy that traditionally is lost by absorption in conventional spiral cavities. This paper presents the results of a prototype UHF SATCOM antenna, shown in Figure 1 at right, measuring just 14" × 14" × 2.5" that is suitable for airborne use. The antenna operates over the 240 - 320 MHz band, weighs less than 5 pounds, may be flush mounted to a platform\´s outer mold line, and provides hemispherical coverage with efficiencies greater than 50%.