Amplifiers Power Tactical Data Links

Tactical radios were originally designed for voice communications, but now must handle data and video information as well. This switchover requires a common-data-link (CDL) solution that not only connects warfi ghters in the fi eld, but such nodes as unattended sensors and unmanned aerial vehicles (UAVs). One of the key components in such a network is the solid-state amplifi er that must provide linear output power with high effi ciency and reliability under extreme environmental conditions.

Legacy CDL solutions have been based on C-band as well as S-band and L-band frequencies, using line-of-sight (LOS) microwave links. Many of these systems have used analog modulation, which is relatively ineffi cient in terms of bandwidth. Bandwidth, in its simplest defi nition, is the rate at which information moves from one electronic device (node) to another. As such, the availability of bandwidth is a central issue in the design and operation of any communication system. As information has become digitized, and the demand for information (bandwidth) has grown, the limitations in many existing communication design paradigms have become increasingly obvious. UAVs today often transmit data in many different formats, complicating data sharing and video transmission between services and, frighteningly, even between units of the same service.

A new form of CDL-compliant system is the tactical common data link (TCDL), with characteristics that help it adapt to the communications needs of evolving manned and UAV platforms. TCDL is a Ku-band digital data link that transmits widebandwidth information using CDL waveform standards. Employing a narrow Ku-band uplink for both payload and vehicle control and a broadband downlink for data transfer, the TCDL can provide full-duplex digital transmission between intelligence collection platforms and surface terminals. The TCDL system supports air-to-surface transmission of radar, imaging, video, and other missioncritical information to 200 km.

To meet the needs of emerging TCDL-equipped systems, CTT, Inc. has developed a pair of amplifi ers with low-noise and high-power capabilities, respectively. The RF transceiver front end continues to be one of the most vital functions in providing real time connectivity and interoperability among an array of manned and unmanned intelligence, surveillance and reconnaissance (ISR) and electronic warfare (EW) systems, and these amplifi ers are designed to elevate performance for a wide range of military applications.

The model AFN/155-1530 lownoise amplifi er (LNA), for example, is optimized for Ku-band frequencies from 14.0 to 14.5 GHz. It has a noise fi gure of less than 1.5 dB with minimum gain of 30 dB to assist in the receive sensitivity of a TCDL-based system. The compact LNA is supplied in a drop-in package measuring 1.60 x 0.66 x 0.22 in. (Fig. 1).

For the transmit site of a TCDL-based system, the model APW/155-4340 solid-state power amplifi er provides 20 W output power from 14.0 to 15.5 GHz. The rugged amplifi er (Fig. 2) features 58-dB small-signal gain, with a respectable noise fi gure of 4.9 dB. It measures 3.9 x 3.5 x 0.67 in. Together the LNA and power amplifi er provide a rugged, miniature RF front-end solution for both airborne and ground terminals.

Both the APW and the AFN amplifi ers are built and inspected to MIL-STD-883, Methods 2010 and 2017, with soldering compliant to J-STD-001, while having all internal components screened to MIL-STD-883, Method 5008. These procedures also make both amplifi ers excellent choices for applications requiring MIL-E-5400, which covers the general requirements for airborne electronic equipment. CTT has developed a range of low-noise and power amplifi ers based on GaAs and GaN device technologies. The company has shipped more than 1,500 amplifi ers into UAV programs, including the Hunter, Shadow, and Predator.

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