Non-foster antenna matching networks using reflection-mode negative-group-delay networks

Almahroug, Alhasan Ali Mosftah (2018). Non-foster antenna matching networks using reflection-mode negative-group-delay networks. University of Birmingham. Ph.D.

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Abstract

Non-Foster networks provide a possible route for broad band matching of antennas. The major challenges when designing non-Foster elements using conventional Negative Impedance Converters (NICs) arise from the stability concerns, due to the existence of the feedback in the circuitry and the generation of negative impedance. Therefore, investigation of alternative means for designing non-Foster elements which are more stable is imperative. This thesis presents a new perspective in designing non-Foster reactive elements based on negative group delay (NGD) networks. A novel reflection-mode NGD network is designed, fabricated and tested. Subsequently, a novel approach which contains a negative resistance amplifier and a Lange coupler is introduced to compensate the losses of the NGD networks. A simple equivalent circuit model (-L, -C) of the proposed NGD-based non-Foster network is presented and can be used to deploy the non-Foster network in an antenna matching network. Theoretical analysis based on Nyquist approach shows that stability can be achieved but practical implementation issues can cause stability problems. . Finally, approximate calculations of the non-linearity and noise performance addressing the operational limitations of the proposed circuit in transmit and receive applications have been introduced.

Type of Work:

Thesis (Doctorates > Ph.D.)

Award Type:

Doctorates > Ph.D.

Supervisor(s):