Dual-band Bandstop Filter(DBBSF) Using Spurline & Stepped-impedance Resonator with Tunable Devices
Author | : Hamad Ghazi Alrwuili |
Publisher | : |
Total Pages | : 183 |
Release | : 2018 |
ISBN-10 | : OCLC:1127912159 |
ISBN-13 | : |
Rating | : 4/5 (59 Downloads) |
Book excerpt: Bandstop filters are very important components in RF microwave systems by virtue of their effective suppression of spurious signals. They are used widely as key components in transmitter and receiver systems. They can be used to block the interfering signals which might affect the transmitted signal. Recently, Dual-Band Bandstop filters (DBBSFs) have become an attractive research field because of their suitability for treating the undesirable double-sideband spectrum in high-power amplifiers and mixers. This feature can be achieved using only a single filter which can reduce both the circuit size and cost of the proposed filter. In addition, this kind of filter has low insertion loss and group delay because of its ability to resonate in the stopband rather than in the passband. This dissertation will present a novel methodology for designing Dual-Band Bandstop Filter with tunable devices. The new filter design will be compact and will integrate two different filter techniques into one. It will use a spurline section with a stepped impedance resonator to approach the performance of dual-band bandstop filter. Both resonators will be fabricated and tested by using microstrip transmission lines. Ferroelectric Capacitors will be modeled and fabricated to be used as tunable elements for the Dual-Band Bandstop filter. These capacitors show low loss, ability to handle power and low distortion when performing isolation or intermodulation. In addition, they have demonstrated a very good tunability while maintaining a comparatively low bias voltage. They can be easily integrated with filter components because of their small size. In this work, chapter one will introduce briefly the importance of the different microwave filter technologies. It will briefly highlight the applications in RF microwave systems. Also, it will provide a brief introduction about tunable technologies that are commonly used in RF systems. Chapter two will present a literature review about the development of Dual-Band Bandstop filters. It will focus more on the microstrip methodology and tunable elements that are used in the application of tunability to bandstop filters. In chapter three, the new design of a Dual-Band Bandstop filter will be introduced. It will integrate a spurline section and a stepped impedance resonator into one compacted filter. The modeling of the new filter design will be presented by using microstrip transmission lines. Chapter four will deal with the tunable devices that are used to tune the new compact filter design. The compact dual-band bandstop filter design will be tuned by using p-n junction varactor diodes at 2.4 GHz and 3.5 GHz. In addition, the same filter design will be tuned by using ferroelectric materials at 2 GHz and 3.5 GHz. The P-n junction varactor diodes will be modeled and simulated by using ADS software. Ferroelectric material will be fabricated and used as tuning elements. The measurement results will be provided along with a comparison between modeling and fabricated filter designs. Finally, in chapter five we are going to discuss the conclusion of this work with some recommendations for future work.