Space

Advanced Multi-band Communications Antenna System (AMCAS)

The Government is interested in obtaining more information concerning the Advanced Multi-band Communications Antenna System (AMCAS) (formerly known as the Airborne Wideband Antenna) system. This affordable antenna system will provide connectivity with multiple beams over multiple frequencies and is meant to be suitable for high data rate satellite communications and possibly Common Data Link (CDL) applications. During the week of 16-20 June 2003, the Government held an Industry Day and follow-on one-on-one discussions to survey industry activities and assess maturity of advanced antenna technology for this capability. During these sessions, Industry requested that the Government provide more specific information regarding the requirements.

The Government has allocated approximately $49 million dollars for the design, development, test, and delivery of an antenna system (Engineering Development Model - (EDM)). It is anticipated a production program for operational systems could be initiated in the latter half of FY09 or early FY10.

The Air Force (AF) user community has stated a need for simultaneous high data rate connectivity to multiple satellites using a common terminal. The initial terminal used will be the Family of Advanced Beyond Line-of-Sight Terminal (FAB-T). FAB-T is an incremental program intended to meet the requirements defined in the Advanced Wideband Terminal (AWT) Operational Requirements Document (ORD) to include an expanding set of configurations with requirements for multiple simultaneous communication links. To make use of the FAB-T capabilities, the AF is seeking a scalable, low profile antenna system solution. While the primary focus of AMCAS is on airborne applications, the Government anticipates exploring the feasibility of using this antenna for some ground applications (e.g. to support highly mobile "communications on the move" scenarios). Key areas of interest for this antenna system include technology maturity, aperture scalability, and antenna system acquisition and installation costs.

In general, the beam of this antenna system will cover the upper hemisphere of the platform to support communication links. In order to make this antenna system useful for application to a variety of platforms, its overall height (including the radome) must be minimized. Much of the emphasis has been on Ka and EHF operation. There is a demand for Ku band satellite links and possibly for Ku band line-of-sight (LOS) CDL.

Because of the low efficiency of high power amplifiers and the physically close spacing of each element, there is expected to be a significant amount of heat generated by the antenna system. This heat must be removed from the array and dissipated. This is critical not only for the transmit apertures but also for the receive aperture, particularly when it is operating with its platform stationary on the ground.

The system capability will require multiple simultaneous beams. In addition, it will be important to mitigate interference from either nearby antennas, or from spurious signals that might be present at the antenna aperture. It will, therefore, require some antenna pattern control to mitigate the interference.

Many different polarization requirements are being considered. They are dependent upon the particular communication link and frequency band. The most demanding requirement will be to provide frequency re-use capability over the scannable field-of-view of the antenna. This requires simultaneous reception (or transmission) of two independent signals on two orthogonal polarizations within the same frequency band and from the same spatial direction.