@misc{indiciaec16bc02b57cc,
  title = {Finite difference time domain modeling of spiral antennas},
  author = {Penney, Christopher W. and Beggs, John H. and Luebbers, Raymond J.},
  year = {1992},
  url = {https://ntrs.nasa.gov/citations/19930009397},
  note = {Source identifier: 19930009397}
}