Low profile antenna stabilization design

Low profile antenna stabilization design

Innovative RF designs allow for beam steering over a large field of regard in a package that is low profile compared to a classic two-axis stabilized gimbal.

The Low Profile Antenna program demonstrated the feasibility of using a variable-inclination continuous transverse stub (VICTS) aperture for a mobile satellite-TV antenna.

The VICTS aperture offers very good RF performance and a wide, steerable field-of-regard in a low-height package. This multi-year, long-term development program included design and production of a prototype aperture, development of the algorithms for pointing, stabilization and tracking, fabrication of a custom gimbaled motion table to simulate vehicle motion, and extensive on-satellite testing. The aperture is shown without radome mounted to the motion table for outdoor, on-satellite testing.

The VICTS aperture has a “virtual” line-of-sight, meaning the antenna assembly does not have a hardware component in which the line-of-sight is fixed. By comparison, the line-of-sight of a dish antenna is fixed within the dish – point the dish, point the line-of-sight. A fixed-dish aperture has the advantage of ease of stabilization, by which the dish is gimbal mounted and two gyroscopes fixed within. The gyroscopes stay orthogonal to the line-of-sight, and direct measurement of the line-of-sight rates is provided. The VICTS aperture has two moving co-axial platters to which gyroscopes can be attached, and the outputs of these gyroscopes must be combined to synthesize the line-of-sight rates. Successfully demonstrating stabilization of the VICTS line-of-sight was a major goal of the program.

An extensive amount of servo and test electronics were developed and integrated as part of the program. Motion table gimbal drive electronics and well as the antenna stabilization controller were built. Additionally, a software-based motion profile generator was designed and implemented to recreate a variety of vehicle driving scenarios.

keyword: stabilization, gimbals, low profile antenna, novel aperture, hybrid phased array, servo control, testbed electronics, motion table, on satellite testing