Office of Technology Transfer – University of Michigan

Method of Generating Negative Group Delay without Using Lossy Circuits

Technology #5449

Serially Fed Phased Array with Beam Squint Elimination

A serially fed phased array with beam squint elimination has been developed by a research team in the electrical engineering and computer science department at the University of Michigan. Conventional military and commercial phased arrays use corporate feeding, in which the lines from the source to each antenna are equivalent, resulting in phase matching between antennae elements. This provides reliable radiation directionality but the system’s required line network suffers from significant ohmic loss and a cumbersome form factor. Serially fed arrays can be more compact and efficient but the phase delay between antennae results in frequency dependent angular propagation or beam squint, which is undesirable for most applications. Through application of serial feeding while simultaneously eliminating beam squint, reliable radiation directionality has been achieved in a compact, efficient, system that is attractive for enhancing many phased array applications.

Negative Group Delay (NGD) Circuit Enables Compact, Efficient Antenna Array

The efficiency improvement and beam squint elimination of this antenna array are results of judicious use of negative group delay (NGD) circuits. Quality factor and impedance matched elements are used to achieve negative group delay without the superfluous loss associated with conventional NGD circuits. Both simulation and experimental demonstration indicate low loss and small phase difference, <2°, over 160 MHz at 10 GHz. This translates to a beam squint of less than 0.4° yielding a compact, efficient system having potential to enhance applications such as aerial oil and gas exploration, on-the-move satellite communication, collision avoidance systems and nondestructive testing (NDT), among others.


  • Military communication (on-the-move)
  • Missile and unmanned vehicle tracking and control
  • Collision avoidance systems
  • Oil and gas exploration
  • Nondestructive testing


  • Compact
  • Efficient
  • Low-loss