Prof. Kelley's Home Page

Research Topics

Reactively Controlled Arrays

Reactively controlled arrays consist of multiple antennas, called elements, that operate simultaneously in order to concentrate radiated signal energy in one or more directions or to enhance sensitivity to received signals in those directions, or both. They can also be designed to minimize radiation (or sensitivity) in other directions. The physical process that makes this possible is the constructive and destructive interference of waves. A reactively controlled array is a type of parasitic array, in which all but one of the elements are not physically connected to the signal source or receiver used with the array. In transmission mode, the parasitic elements intercept some of the radiated energy from the driven element (the one connected to the source) and then re-radiate that energy. In reception mode, the parasitic elements "scatter" (reflect) the incoming signal energy, some of which impinges on the driven element.

Most parasitic arrays are "static" designs, meaning that once they have been built, their radiation (sensitivity) characteristics and other peformance parameters are fixed. In a reactively controlled array (RCA), the parasitic elements have user-controlled reactances (capacitors and/or inductors) connected to them. These variable reactive loads allow control over many of the performance characteristics of the antenna, such as the directions in which radiated signal energy is concentrated (or in which sensitivity to received signals is enhanced).

My research in this area has focused on investigating different physical arrangements of array elements in RCAs in order to optimize performance for various applications, and on developing efficient methods for determining the reactance values necessary to achieve specific design goals.

Recent contributions include:

  • Developed a method to increase the speed of calculation and optimization of radiation patterns of parasitic arrays whose elements are loaded with reactances (inductors and capacitors).
  • Implemented an efficient interpolation method to obtain mutual impedances and radiation patterns of array elements over a wide range of frequencies using impedance and pattern data calculated at only a few frequencies. The method is intended to improve the speed of optimization procedures applied to array design.
  • Developed a new type of reactively controlled array in which the elements are arranged just above a ground plane. The direction of strongest radiation can be steered over most of the hemisphere above the ground plane by varying the loads applied to the parasitic elements.

Bucknell Student Contributors

  • Sam Reier (BSEE '02)

Publications

  • David F. Kelley, "A Reactively Controlled Array over Ground Plane for Hemispherical Coverage," Proc. IEEE Antennas and Propagation Society International Symposium, San Diego, CA, July 2008, DOI: 10.1109/APS.2008.4619411.
  • David F. Kelley and Samuel D. Reier, "Efficient Pattern and Impedance Bandwidth Analysis of Reactively Steered Arrays," Proc. 2004 Antenna Applications Symposium, Monticello, IL, Sept. 2004, pp. 99-116.
  • David F. Kelley, "Efficient Calculation of Radiation Patterns for Reactively-Steered Array Antennas," Proc. IEEE Antennas and Propagation Society International Symposium, vol. 3, Monterey, CA, June 2004, pp. 2635-2638.
 

Site maintained by:
Associate Professor David F. Kelley
Electrical and Computer Engineering Department, Bucknell University, Lewisburg, PA 17837
e-mail: dkelley AT bucknell DOT edu

Updated: January 20, 2019

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