Variable bandwidth planar coupled resonator filters utilizing tunable non-resonant node inverters

Sharma, Satyam Kumar (2018-12)

Thesis (PhD)--Stellenbosch University, 2018.

Thesis

ENGLISH ABSTRACT: This dissertation presents a novel design technique for designing microstrip staircase and pedestal substrate integrated waveguide (SIW) filters with tunable bandwidth. The design technique utilizes non-resonant nodes as inverters, allowing the inter-resonator coupling to be varied by varactor diodes. For the microstrip implementation, a circuit model of the proposed tunable nonresonant node inverter (NI) to be implemented in parallel coupled line staircase filter is presented. Generalized synthesis design equations are formulated and dimensional design charts are presented to aid designers in designing tunable staircase filters using NI. Reconfigurable second order and third order parallel coupled line staircase filters with constant absolute bandwidth are designed and measured. For the substrate integrated waveguide (SIW) implementation, the proposed tunable non-resonant node inverter is implemented in a T-ridge pedestal SIW resonator based filter topology. A detailed dimensional analysis for integrating NI in T-ridge SIW filters is presented and design charts are formulated. A design procedure is proposed to design NI based T-ridge SIW filters with bandwidth control for a given filter specification. A second order T-ridge SIW filter with tunable bandwidth is designed and simulated. The designed reconfigurable filters using NI offer significant advantages over most of the other reconfigurable filter designs. The proposed synthesis method comprising of design equations and design charts presents an insight into the dimensional information required to design these filters for a given specification. Further, it reduces the reliance on full wave optimization and thus results in reduced computational cost and design time. The designed and measured prototype filters based on NI demonstrate negligible centre frequency deviation as the bandwidth is tuned. The use of spatial biasing mechanism reduces the complexity of the filter designs as additional biasing circuit is not required to bias tuning elements

AFRIKAANSE OPSOMMING: Hierdie proefskrif bied 'n nuwe ontwerpstegniek aan vir die ontwerp van mikrostrook- en oppervlak-geïntegreerde-golfleier (OGG)-filters met verstelbare bandwydte. Die tegniek gebruik nie-resonante nodusse as omkeerders en maak dit moontlik vir tussen-resoneerder koppelings om verstel te word deur varaktor diodes. Vir mikrostrook implementerings word 'n stroombaanmodel van die voorgestelde omkeerder in newe-gekoppelde trap-filters aangebied. Veralgemeende sintese vergelykings word geformuleer en strukturele ontwerpsgrafieke word aangebied om ontwerpers in staat te stel om hierdie klas van filters te ontwerp. Verstelbare tweede en derde orde filters met konstante absolute bandwydte word ontwerp en gemeet. Vir OGG-implementering, word die voorgestelde tegniek ge-implementeer as 'n gevoude T-rif filter topologie. 'n Detail strukturele analise word aangebied, sowel as 'n ontwerpsprosedure. 'n Tweede orde filter word ontwerp en gesimuleer. Die gebruik van hierdie tegniek bied beduidende voordele bo meeste ander verstelbare topologieë. Die voorgestelde sintese tegniek, bestaande uit ontwerpsvergelykings en ontwerpsgrafieke, bied ook insig in die strukturele aspekte wat benodig word om 'n gegewe spesifikasie te haal. Dit verminder verder die afhanklikheid op volgolf analise, en dus ook die berekeningskoste en ontwerptyd. Die prototipes demonstreer weglaatbare senterfrekwensieveranderinge met verstelling van bandwydte. Die gebruik van ruimtelike voorspanning verminder die stroombaankompleksiteit.

Please refer to this item in SUNScholar by using the following persistent URL: http://hdl.handle.net/10019.1/104819
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