Advanced Extremely High Frequency (AEHF) System
Published July 11, 2012
The Advanced Extremely High Frequency System is a joint service satellite communications system that will provide survivable, global, secure, protected, and jam-resistant communications for high-priority military ground, sea and air assets. Advanced EHF will allow the National Security Council and Unified Combatant Commanders to control their tactical and strategic forces at all levels of conflict through general nuclear war and supports the attainment of information superiority.
The AEHF System is the follow-on to the Milstar system, augmenting and improving on the capabilities of Milstar, and expanding the MILSATCOM architecture. AEHF will provide connectivity across the spectrum of mission areas, including land, air and naval warfare; special operations; strategic nuclear operations; strategic defense; theater missile defense; and space operations and intelligence.
The AEHF system consists of four satellites in geosynchronous earth orbit that provides 10 times the throughput of the 1990s-era Milstar satellites with a substantial increase in coverage for users. AEHF-1 was launched on August 14, 2010 and AEHF-2 was launched on May 4, 2012, AEHF-3 is expected to launch in fall 2013 while AEHF-4 is projected to launch sometime in 2017. AEHF will provide continuous 24-hour coverage between 65 degrees north and 65 degrees south latitude. The AEHF system is composed of three segments: space (the satellites), ground (mission control and associated communications links) and terminals (the users). The segments will provide communications in a specified set of data rates from 75 bps to approximately 8 Mbps. The space segment consists of a cross-linked constellation of four satellites. The mission control segment controls satellites on orbit, monitors satellite health and provides communications system planning and monitoring. This segment is highly survivable, with both fixed and mobile control stations. System uplinks and crosslinks will operate in the extremely high frequency range and downlinks in the super high frequency (SHF) range. The terminal segment includes fixed and ground mobile terminals, ship and submarine terminals, and airborne terminals used by all of the Services and international partners (Canada, Netherlands and UK). MILSATCOM is responsible for acquisition of the space and ground segments as well as the Air Force terminal segments. The Army and Navy will acquire their own terminals.
Primary Function: Near-worldwide, secure, survivable satellite communications
Primary Contractor: Lockheed Martin Space Systems Company
Payload: Onboard signal processing, crossbanded EHF/SHF communications
Antennas: 2 SHF Downlink Phased Arrays, 2 Crosslinks, 2 Uplink/Downlink Nulling Antennas, 1 Uplink EHF Phased Array, 6 Uplink/Downlink Gimbaled Dish Antenna, 1 Each Uplink/downlink earth coverage horns
Capability: Data rates from 75 bps to approximately 8 Mbps