@inproceedings{nikolaou_ponchak_papapolymerou_tentzeris, 
  title={Shorted annular slot antenna (ASA) matched at three different frequencies}, 
  DOI={10.1109/aps.2005.1551614}, 
  publisher={IEEE}, 
  author={Nikolaou and Ponchak and Papapolymerou and Tentzeris}
  }