Negative group delay-enabled reconfigurable non-foster elements and beamforming networks
Description
TitleNegative group delay-enabled reconfigurable non-foster elements and beamforming networks
Date Created2021
Other Date2021-10 (degree)
Extent1 online resource (xv, 107 pages) : illustrations
DescriptionAs a counterintuitive phenomenon, negative group delay (NGD) was first found in regions of strong anomalous dispersion. The peak of the pulse emerges from the device's output at an instant before the peak of the pulse enters its input. Later, the circuit approaches of NGD are realized. In this work, reconfigurability enhanced distributed amplifier (DA) -based NGD circuit and its applications in realizing non-Foster elements and beamforming networks will be discussed. The proposed circuit incorporates varactors at the input and output ports of the DA-based NGD circuit, notably enhances the tuning range for the amplitude, overall phase, and the NGD responses, thereby enables flexible S-parameter synthesis with a wider reconfigurable range. Compared with other approaches, the reconfigurability enhanced DA-based NGD circuit has the advantages of:
1) Simple structure that enables gain, phase, and NGD to be widely tuned individually
2) Wide bandwidth performance with the distributed amplifier design
3) Good impedance matching and unconditionally stability
4) Can be fabricated on MMIC platform, easy to work at higher frequency
Firstly, we will give a review of the current NGD circuits and their performances. Secondly, a description of the proposed distributed-amplifier-based NGD circuit will be provided, including the theory and objectives. In the theory part, a general N-stage transfer function for the proposed reconfigurable NGD circuit is derived and discussed. A 2-stage case is given as an illustrative proof-of-concept example. The objectives include how to create tunable non-Foster elements and tunable squint-free beamforming networks by applying the reconfigurability enhanced NGD circuits into the design. Thirdly, prototypes based on the reconfigurable NGD circuits will be demonstrated, including a reconfigurable negative capacitor, squint-free antenna beamforming networks, and others.
A tunable NGD enabled negative capacitor is simulated and fabricated; the prototype shows it can be tuned within an outstanding range from -1.0 pF to -4.0 pF over a bandwidth of 100 MHz at 1 GHz. A series-type squint-free antenna array feeding network is simulated and fabricated, and devices with/without varactors are compared. By synthesizing a low-dispersion superluminal antenna array feeding line, we first realized a main beam steerable series-type squint-free antenna array. Experimental results show that the main beam of the NGD-enabled antenna array has a tuning range from -15° to 15° within a squint-free bandwidth of 100 MHz at 2 GHz. Compared with the one without varactors, the main beam tuning range has tripled.
Due to the transversal-filter-based design, the above applications can benefit from a wider operation bandwidth by either applying more parallel stages or cascading more series unit cells.
NotePh.D.
NoteIncludes bibliographical references
Genretheses
LanguageEnglish
CollectionSchool of Graduate Studies Electronic Theses and Dissertations
Organization NameRutgers, The State University of New Jersey
RightsThe author owns the copyright to this work.
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