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Open Access Publications from the University of California

Non-Foster Circuits for High Performance Antennas: Advantages and Practical Limitations

  • Author(s): Jacob, Minu Mariam
  • Advisor(s): Sievenpiper, Daniel F
  • et al.

The demand for miniaturized, broadband communication systems has created a need for electrically small, broadband antennas. However, all passive electrically small antennas have a fundamental gain-bandwidth limitation related to their electrical size, as first described by Wheeler and Chu. This limitation can be overcome using active non-Foster circuits (negative inductors and/or negative capacitors), which can deliver a broadband input match with active matching techniques, or can help reduce phase dispersion using negative delay effects. This thesis will illustrate the advantages of non-Foster circuits in obtaining broadband small antennas, in addition to examining their practical limitations due to noise in receive applications, and nonlinearity in transmit applications.

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