Experiences

Can we help you? Here are descriptions of some of the projects from our experience base

X-band Fiber Optic Links for ground-based phased-array radar

X-band Fiber Optics

This project required the development of high performance, ultra-miniature directly-modulated fiber optic link equipment for a large, ground-based X-band radar system.  It included research and development of highly integrated laser transmitter and photoreceiver products, as well as all-optical true time delay beamforming equipment.  Successful implementation of the products also required the development of novel manufacturing techniques and processes, as well as manufacturing tools and training.

Shipboard Fiber Optics

Modern broadband shipboard electronic warfare (EW) receivers are sensitive and capable enough to locate and track targets that would have been invisible just a decade ago.  Modern systems rely on phased array antennas and complicated beamforming and processing hardware and software.  To maximize their field of view, the antenna apertures need to be placed as high on a ship as feasible.  The processing electronics, on the other hand, would rather be placed below decks, where the environment is controlled and there is less impact on ship stability. 


In the past, distributing radar signals over heavy and lossy coaxial cable made for severe limitations in overall bandwidth.  Enter fiber optics.  By providing extremely broadband link capacity, radar waveforms can be effectively distributed from the harsh above-decks environment to the relatively safer below decks environment with minimal performance degradation.   


This project involved:


  • development and manufacture of high density ultra-broadband military-hardened fiber optic links;
  • novel techniques for maximizing reliability and maintainability;
  • qualification planning and execution;
  • implementation of a complete vertical manufacturing facility, starting from a bare concrete floor;
  • long-term contract negotiations and agreements both as a buyer from key supply-chain partners and as a subcontractor to major aerospace/defense companies;
  • leadership for the entire business area, including IR&D, capital, and P&L; and
  • the direct management of a team of 40 engineers, scientists, and manufacturing professionals.


This system entered full production in 2016.

Active Array Impedance

As a phased array antenna is steered off boresight, the load impedance presented by the radiating elements will change.  This is caused by changes in the mutual coupling between the elements, and is known as active array impedance.  As the load changes, so does the reflected power back into the amplifier(s) driving the array.  The impedance changes can become so great that the allowable steering angles are significantly reduced.  In this project, a circularly polarized phased array designed for air traffic control (S-band) was characterized and optimized for large 2-dimensional steering, while maintaining good effective impedance.  Element design techniques were developed that allowed scan angles up to 60° while maintaining good impedance matching, efficient power transfer, and low cross-polarization interference.  The work provided a major defense contractor a technical edge, enabling participation in a highly competitive program.

Sonar Shape Filters

Active sonar works by transmitting a “ping” into ocean water then listening for and analyzing the reflected return signal.  In military systems, the objective is to locate other ships, some of which may be hidden underwater or over the visible horizon.  In shallow water or dense environments, reflections from non-ship objects such as the ocean floor, physical obstructions, and large sea life (whales) can create ambiguity and uncertainty.  This project involved the analysis and complex display of multiple successive sonar returns to develop a time-based multidimensional characterization of target returns in time and space.  By understanding the physical shape of an object and determining how it moves through time, sonar systems can help operators distinguish between large obstructions and actual targets.  Application of this technology provided a competitive advantage to a major defense contractor.

Hydrogen Poisoning

Microwave and millimeterwave high electron mobility transistors (HEMTs), and the integrated circuits that are made from them, are often manufactured from highly engineered InGaAs material systems, with transistor gate contacts based on a deposition of Ti, W and Au.  Free molecular hydrogen gas can form Ti-H “hydrides” that affect the conduction characteristics of the gate contacts.  This in turn changes the pinch-off voltage of the transistor, causing a reduction in gain.  In normal atmospheric concentrations there is not enough molecular hydrogen to affect these devices.  But when devices are packaged into hermetically sealed enclosures, the residual hydrogen left over from plating processes and materials outgassing can be substantial.   This challenge involved the development of a reliability program to characterize the long-term performance risks of hydrogen poisoning due to the driving factors of temperature and molecular concentration of hydrogen, including mitigation techniques.  This work supported the large-scale industry-wide implementation of packaged HEMT and HEMT-based MMIC devices for commercial and military communications satellites.

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