Transmit receive module for S-band electronically scanned antenna with on board digital control, health monitoring and telemetry

Abstract

Satellites require timely tracking, telemetry, and command (TT&C) for payload operation. The ground antenna is one of the key elements that enable satellite control and payload operations. To support the operation of a large number of satellites at various orbits, operators need a network of antennas distributed around the globe, such as the air force satellite control network (AFSCN), to contact satellites at a predetermined time and location. Currently, they use large mechanically steered parabolic dishes to provide hemispherical coverage and simultaneous transmit (Tx) and receive (Rx) capabilities in support of Department of Defense (DoD) satellite operations (SATOPS) network designers used reflector antennas because of relatively low acquisition cost. The current reflector antennas used to support satellite operations are approximately 10 m in diameter and are susceptible to single point failure and long downtime for repair and maintenance. S-Band component technology provided by the cell phone industry allows an affordable electronically scanned antenna (ESA). Current SATOPS require a more efficient and flexible antenna system. The ESA can offer superior performance, operability, adaptability and maintainability for satellite operation. This paper presents the design of a TR module that can provide one transmit (Tx) and two receive (Rx) links to a satellite. The TR module is part of a dome shaped antenna that could provide multiple simultaneous ground to satellite links. This geodome antenna provide multiples simultaneous operations with pointing and acquisition taking seconds. One dome antenna can replace the capability of three AFSCN parabolic dishes. The next generation low cost TR module developed by the AFRL/Information Grid Division (IFG) and Princeton Microwave Technology Inc. for the next generation of the AF Satellite Control Network (AFSCN). The TR module differs from previous modules in Ref S.S. Bharj et al, (2000) and P.J. Oleski et al, (2004) in that it consists of a single Tx channel capable of 33 dBm of output power and two Rx channels with a gain of 30 dB per channel In addition, beam switching and on board digital control has been implemented where the Tx and Rx channels provide four-bit phase shift. In addition to the control functions, built-in test (BIT) circuits monitors the health and status of the RF devices. This function utilizes a low-power micro-controller to output digital data for each of the power and low noise amplifiers, via A/D converters. The bandwidth of the TR module has been designed to cover both the unified S-Band (USB) and satellite ground link subsystem (SGLS). The TR functions are combined at the output via a ceramic resonator diplexer comprised of a band pass-band stop filter. The control of the TR module is conducted via a single programmable logic device (PLD) controller through a DAQ computer interface. The TR module has been designed to meet the cost objective for a dome antenna with approximately 47,000 TR modules. A Td generation 78 element triangular panel of TR modules is now planned to be developed, leveraging off lessons learned from generation one. This paper describes the layout and design of the 2nd generation TR module