Miniaturization Trends in Substrate Integrated Waveguide (SIW) Filters: A Review

This review provides an overview of the technological advancements and miniaturization trends in Substrate Integrated Waveguide (SIW) filters. SIW is an emerging planar waveguide structure for the transmission of electromagnetic (EM) waves. SIW structure consists of two parallel copper plates which are connected by a series of vias or continuous perfect electric conductor (PEC) channels. SIW is a suitable choice for designing and developing the microwave and millimetre-wave (mm-Wave) radio frequency (RF) components: because it has compact dimensions, low insertion loss, high-quality factor (QF), and can easily integrate with planar RF components. SIW technology enjoys the advantages of the classical bulky waveguides in a planar structure; thus is a promising choice for microwave and mm-Wave RF components

Novel substrate integrated waveguide filters and circuits

The main work in this thesis is to explore novel microwave filters with more compact size and improved performance by taking advantage of new substrate integrated waveguide (SIW) structures, such as the ridge substrate integrated waveguide, half mode substrate integrated waveguide (HMSIW) and SIW with complementary split ring resonators (CSRRs). This thesis therefore presents the following topics: 1. Development of a design strategy to convert from a conventional ridge waveguide configuration with solid walls to the SIW counterpart, and the design of a bandpass filter based on the ridge SIW with the proposed design method. 2. Development of a ridged HMSIW to reduce the physical size of the HMSIW by loading the HMSIW with a ridge, and application of the ridged HMSIW to the design of compact bandpass filters. 3. Development of a broadside-coupled complementary split ring resonator and a capacitively-loaded complementary single split ring resonator to reduce the size of SIW with conventional CSRRs, and application of the proposed modified structures in the design of SIW and HMSIW filters with improved compactness and performance. 4. Investigation of the application of the complementary electric-LC (CELC) resonator in SIW filters with improved stopband performance, and development of a cascaded CELC resonator to further enhance the out-of-band performance

Microwave and Millimeter-wave Miniaturization Techniques, and Their Applications

Miniaturization is an inevitable requirement for modern microwave and mm-wave circuits and systems. With the emerging of high frequency monolithic integrated circuits, it is the passive components’ section that usually occupies the most of the area. As a result, developing creative miniaturization techniques in order to reduce the physical sizes of passive components while keep their high performance characteristics is demanding. On the other hand, it is the application that defines the importance and effectiveness of the miniaturization method. For example, in commercial handset wireless communication systems, it is the portability that primarily dictates miniaturization. However, in case of liquid sensing applications, the required volume of the sample, cost, or other parameters might impose size limitations. In this thesis, various microwave and mm-wave miniaturization methods are introduced. The methods are applied to various passive components and blocks in different applications to better study their effectiveness. Both componentlevel designs and system-level hybrid integration are benefited from the miniaturization methods introduced in this thesis. The proposed methods are also experimentally tested, and the results show promising potential for the proposed methods

Análisis y diseño de filtros compactos de microondas basados en cristales electromagnéticos y resonadores metamateriales

[SPA] Esta tesis doctoral se presenta bajo la modalidad de compendio de publicaciones. La presente tesis está centrada en el análisis y síntesis de dispositivos de microondas. Más concretamente, se han desarrollado tres tipos de celdas basadas en estructuras metamateriales, las cuales se han aplicado en el diseño original de filtros compactos en tecnología planar (línea microtira, guía coplanar y guía de onda integrada en sustrato, SIW). Las celdas y dispositivos propuestos pueden ser de un gran interés para los futuros sistemas de comunicación. Por un lado, la tecnología planar es un método de fabricación maduro y de bajo coste y, por otro lado, los dispositivos basados en estructuras metamateriales presentan propiedades electromagnéticas singulares, que permiten reducir el tamaño y superar las limitaciones de los dispositivos convencionales. Entre los diferentes metamateriales que existen, se utilizaron los pertenecientes a los cristales electromagnéticos (Electromagnetic Band Gap, EBG) y a los medios de Veselago. Los EBG convencionales son estructuras con una única fila de patrones circulares periódicos, grabados en el plano de masa de una línea microtira. Estas estructuras exhiben bandas de frecuencia en las que se permiten y se impiden la propagación electromagnética. Este comportamiento es conocido como reflector de Bragg. Las estructuras EBG propuestas sustituyen los patrones circulares por celdas basadas en geometrías fractales de Koch (KFEBG), creadas a partir de una configuración hexagonal. Estas celdas KFEBG permiten superar el límite constructivo radio-periodo (r/a) en EBG convencionales, definido en 0.45. Cuando r/a 0.5, la estructura microtira-KFEBG presenta una amplia banda de rechazo, inusual para este tipo de configuración. Por ello, se aplicó la estructura periódica KFEBG con r/a > 0.5 en el diseño de filtros compactos paso-bajo en tecnologías microtira y SIW. Para mejorar la respuesta en frecuencia y reducir el tamaño de estos filtros, se realizó una apodización modulada de los parámetros de diseño. Finalmente, se desarrolló un método de síntesis original para lograr estos diseños. Por otro lado, los medios de Veselago, también conocidos como materiales zurdos (Left-Handed, LH), se caracterizan por poseer partes reales de permitividad y de permeabilidad simultáneamente negativas. En ellos, es posible la propagación de ondas regresivas entre otros fenómenos inusuales. Las configuraciones iniciales están basadas en resonadores de anillos (celdas) SRR y CSRR (Split ring resonator, Complementary Split ring resonator), acoplados a una línea de transmisión. A posteriori, se desarrollaron las versiones abiertas OSRR (Open Split ring resonator) y OCSRR (Open Complementary Split ring resonator) que permiten una conexión directa con la línea de transmisión, una mayor facilidad de diseño de dispositivos y un tamaño reducido con respecto a los SRR y CSRR. En este trabajo, se propone dos celdas basadas en resonadores de anillos abiertos: la OISRR (Open Interconnected Split Ring Resonator) de tipo mono-planar como las anteriores y la DOSRR (Double- Sided Open Split Ring Resonator) de tipo bi-planar con parámetros de diseño en dos planos diferentes. Ambas celdas poseen un tamaño reducido como la OSRR y características interesantes. Las celdas DOSRR y OISRR se aplicaron, respectivamente, al diseño en tecnología planar de filtros compactos pasobanda con altos niveles de rechazo y filtros compactos rechazo-banda de alta selectividad (notch). [ENG] This thesis focuses on the analysis and synthesis of microwave devices. More specifically, three types of cell structures metamaterials have been developed. They have been applied to the original design of compact filters in planar technology (microstrip, coplanar waveguide CPW and substrate integrated waveguide SIW). The proposed cells and devices may be of great interest for future communication systems. On the one hand, the planar technology is a mature and low cost method of manufacturing, and on the other hand, the devices based on metamaterial structures show unique electromagnetic properties which will make possible reducing the size and overcoming the limitations of conventional devices. Among the different metamaterials existing, we used those belonging to electromagnetic crystals (Electromagnetic Band Gap, EBG) and Veselago media. Conventional EBGs in microstrip technology are a periodic structure with one row of circular patterns etched on the ground plane. This structure exhibits bands of frequencies in which electromagnetic propagation is not allowed as a Bragg reflector. EBG structures proposed changing the circular patterns by cells based on fractal geometry Koch (KFEBG), created from a hexagonal shape. KFEBG cells allow the realization of structure with r/a (radii/period) ratio higher than 0.45 (which is the upper limit of the conventional 1-D EBG structure). When r/a 0.5, the microstrip- KFEBG structure presents a wide stopband, unusual on this kind of configuration. Therefore, the periodic structure KFEBG is applied to r/a> 0.5 in the design of compact low-pass filters in microstrip technology and SIW. In order to improve the frequency response and reduce the size of these filters, a modulated apodization of the design parameters was performed. And finally, an original synthesis method to achieve these designs is developed. Furthermore, Veselago media, also called left-handed materials (LH), are characterized by real parts of permittivity and permeability negative simultaneously. These media make possible the spread of regressive waves among other unusual phenomena. First cells are based on split ring resonators (SRR) and complementary split ring resonators (CSRR) coupled to a transmission line. Later, the open versions OSRR (Open Split ring resonator) and OCSRR (Open Complementary Split ring resonators) are developed; these cells allow direct connection to the transmission line, a greater ability to design devices and a reduced size compared to SRR and CSRR cells. In this work, two new cells based on open rings resonators are presented, OISRR (Open Interconnected Split Ring Resonator) is a mono-planar cell as above and DOSRR (Double- Sided Open Split Ring Resonator) is a bi-planar cell with design parameters in two different planes. Both cells have a reduced size like OSRR and show interesting features. The DOSRR and OISRR cells were applied to the design in planar technology of compact band-pass filters with high levels of rejection and high selectivity compact stop-band filters (notch), respectively.[ENG] This doctoral dissertation has been presented in the form of thesis by publication.This thesis focuses on the analysis and synthesis of microwave devices. More specifically, three types of cell structures metamaterials have been developed. They have been applied to the original design of compact filters in planar technology (microstrip, coplanar waveguide CPW and substrate integrated waveguide SIW). The proposed cells and devices may be of great interest for future communication systems. On the one hand, the planar technology is a mature and low cost method of manufacturing, and on the other hand, the devices based on metamaterial structures show unique electromagnetic properties which will make possible reducing the size and overcoming the limitations of conventional devices. Among the different metamaterials existing, we used those belonging to electromagnetic crystals (Electromagnetic Band Gap, EBG) and Veselago media. Conventional EBGs in microstrip technology are a periodic structure with one row of circular patterns etched on the ground plane. This structure exhibits bands of frequencies in which electromagnetic propagation is not allowed as a Bragg reflector. EBG structures proposed changing the circular patterns by cells based on fractal geometry Koch (KFEBG), created from a hexagonal shape. KFEBG cells allow the realization of structure with r/a (radii/period) ratio higher than 0.45 (which is the upper limit of the conventional 1-D EBG structure). When r/a 0.5, the microstrip- KFEBG structure presents a wide stopband, unusual on this kind of configuration. Therefore, the periodic structure KFEBG is applied to r/a> 0.5 in the design of compact low-pass filters in microstrip technology and SIW. In order to improve the frequency response and reduce the size of these filters, a modulated apodization of the design parameters was performed. And finally, an original synthesis method to achieve these designs is developed. Furthermore, Veselago media, also called left-handed materials (LH), are characterized by real parts of permittivity and permeability negative simultaneously. These media make possible the spread of regressive waves among other unusual phenomena. First cells are based on split ring resonators (SRR) and complementary split ring resonators (CSRR) coupled to a transmission line. Later, the open versions OSRR (Open Split ring resonator) and OCSRR (Open Complementary Split ring resonators) are developed; these cells allow direct connection to the transmission line, a greater ability to design devices and a reduced size compared to SRR and CSRR cells. In this work, two new cells based on open rings resonators are presented, OISRR (Open Interconnected Split Ring Resonator) is a mono-planar cell as above and DOSRR (Double- Sided Open Split Ring Resonator) is a bi-planar cell with design parameters in two different planes. Both cells have a reduced size like OSRR and show interesting features. The DOSRR and OISRR cells were applied to the design in planar technology of compact band-pass filters with high levels of rejection and high selectivity compact stop-band filters (notch), respectively.El presente documento se corresponde a una Tesis por compendio de publicaciones. Está formada por un total de siete artículos: 1. Juan de Dios Ruiz, Félix L. Martínez, and Juan Hinojosa: “1D Koch fractal electromagnetic bandgap microstrip structure with r/a ratios higher than 0.5”. Microwave and Optical Technology Letters, Vol. 53, No. 3, pp. 646-649, March 2011. (JCR-ISI, índice de impacto: 0,623, Q4). 2. Juan de Dios Ruiz, Félix L. Martínez, and Juan Hinojosa: “Novel compact wideband EBG structure based on tapered 1-D Koch fractal patterns”. IEEE Antennas and Wireless Propagation Letters, Vol. 10, pp. 1104-1107, 2011. (JCR-ISI, índice de impacto: 1,948, Q2). 3. Juan de Dios Ruiz, Félix L. Martínez, and Juan Hinojosa: “Optimization of chirped and tapered microstrip Koch fractal electromagnetic band-gap (KFEBG) structures for improved low-pass filter design”. IET Microwaves, Antennas and Propagation, Vol. 9, pp 889-897, Jun. 2015. (JCR-ISI, índice de impacto: 0,969, Q3). 4. Juan de Dios Ruiz, Félix L. Martínez, Alejandro Álvarez Melcón and Juan Hinojosa: “Substrate integrated waveguide (SIW) with Koch fractal electromagnetic bandgap structures (KFEBG) for bandpass filter design”. IEEE Microwave and Wireless Components Letters, Vol. 25, pp. 160-162, March 2015. (JCR-ISI, índice de impacto: 2.236, Q1). 5. Juan de Dios Ruiz and Juan Hinojosa: “Double-sided open split ring resonator for compact microstrip band-pass filter design”. IET Microwaves, Antennas and Propagation, Vol. 6, pp. 846-853, June 2012. (JCR-ISI, índice de impacto: 0,969, Q3). 6. Juan de Dios Ruiz, Juan Hinojosa, and Alejandro Álvarez Melcón: “Microstrip notch filters based on open interconnected Split ring resonators (OISRRs)”. Ap- ii plied Physics A (Materials Sciences & Processing), vol. 112, pp. 263-267, August 2013. (JCR-ISI, índice de impacto: 1.694, Q2) 7. Juan de Dios Ruiz and Juan Hinojosa: “A shunt series LC circuit for compact CPW notch filter design”. IET Microwaves, Antennas and Propagation, Vol. 8, pp. 125-129, January 2014. (JCR-ISI, índice de impacto: 0,969, Q3).Universidad Politécnica de CartagenaPrograma Oficial de Posgrado en Tecnologías de la Información y Comunicacione

Design and analysis of miniaturized substrate integrated waveguide reconfigurable filters for mm-wave applications.

Doctoral Degree. University of KwaZulu-Natal, Durban.Microwave filters are an integral part of communication systems. With the advent of new technologies, microwave devices, such as filters, need to have superior performance in terms of power handling, selectivity, size, insertion loss etc. During the past decade, many applications have been added to the communication networks, resulting in communication systems having to operate at high frequencies in the region of THz to achieve the stringent bandwidth requirements. To achieve the requirements of the modern communication system, tunability and reconfigurability have become fundamental requirements to reduce the footprint of communication devices. However, the communication systems that are more prevalent such as planar circuits have either a large footprint or are not able to handle large amounts of power due to radiation leakage. In this thesis, Substrate Integrated Waveguide (SIW) technology has been employed. The SIW has the same properties as the conventional rectangular waveguide; hence it benefits from the high quality (Q) factor and can handle large powers with small radiation loss. The Half-mode (HMSIW), Quarter-mode (QMSIW), and Eighth-mode (EMSIW) cavity resonators have been designed and used for the miniaturization of the microwave filters. The coupling matrix method was used to implement a filter that uses cross-coupled EMSIW and HMSIW cavity resonators to improve the selectivity of the filter. Balanced circuit techniques have been used to design the circuits that preserve communication systems integrity whereby the Common Mode (CM) signal was suppressed using Deformed Ground Structure (DGS) and a center conductor patch with meandered line. For the designed dual-band filter, the common mode signal was suppressed to -90 dB and - 40 dB for the first and second passband, respectively. The insertion loss observed is 2.8 dB and 1.6 dB for the first and second passband, respectively. For tunability of the filter, a dual-band filter utilizing triangular HMSIW resonators has been designed and reconfigurability is achieved by perturbing the substrate permittivity by dielectric rods. The dielectric rods’ permittivity was changed to achieve tunability in the first instance, and then the rods’ diameter changed in the second instance. For the lowerband, frequency is tunable from 8.1 GHz to 9.15 GHz, while the upper band is tuned from 14.61 GHz to 16.10 GHz. A second order SIW filter with a two layer substrate was then designed to operate in the THz region. For reconfigurability, Graphene was sandwiched between the Silicon Di-Oxide substrate and the top gold plate of the filter, and the chemical potential of Graphene was then varied by applying a dc bias voltage. With a change in dc voltage the chemical potential of Graphene changes accordingly. From the results, a chemical potential change of 0.1 eV to 0.6 eV brings about a frequency change from 1.289 THz to 1.297 THz

Microwave and Millimeter-wave Miniaturization Techniques, and Their Applications

Miniaturization is an inevitable requirement for modern microwave and mm-wave circuits and systems. With the emerging of high frequency monolithic integrated circuits, it is the passive components’ section that usually occupies the most of the area. As a result, developing creative miniaturization techniques in order to reduce the physical sizes of passive components while keep their high performance characteristics is demanding. On the other hand, it is the application that defines the importance and effectiveness of the miniaturization method. For example, in commercial handset wireless communication systems, it is the portability that primarily dictates miniaturization. However, in case of liquid sensing applications, the required volume of the sample, cost, or other parameters might impose size limitations. In this thesis, various microwave and mm-wave miniaturization methods are introduced. The methods are applied to various passive components and blocks in different applications to better study their effectiveness. Both componentlevel designs and system-level hybrid integration are benefited from the miniaturization methods introduced in this thesis. The proposed methods are also experimentally tested, and the results show promising potential for the proposed methods

Innovative Microwave and Millimetre-Wave Components and Sub-Systems Based on Substrate Integration Technology

RÉSUMÉ Avec le rapide développement des technologies microondes et millimétriques, les spécifications de conception des circuits et systèmes sont de plus en plus exigeantes. La tendance pour le développement des systèmes de communication se dirige vers un poids minimisé, une taille réduite, de multiples fonctions, une fiabilité accrue et un faible coût. Ainsi, des technologies microondes et millimétriques faibles coûts, performantes et convenant à une production de masse sont critiques pour développer avec succès des systèmes commerciaux. La technologie à guide d’ondes rectangulaire a toujours été parmi les plus populaires pour la fabrication des systèmes millimétriques. Cependant, une difficulté majeure est reliée à leur intégration avec des composants actifs et les autres types de lignes de transmission conventionnelles, telle que microruban ou coplanaire… Les technologies de Circuits Intégrés au Substrat (CISs), incluant la technologie Guide Intégré au Substrat (GIS), qui peut être intégrée dans les substrats diélectriques avec de faibles pertes d’insertion et de radiation, sont une famille de nouvelles structures à ondes guidées. Ces dernières permettent de faire un pont entre les structures planaires et non-planaires. Jusqu’à maintenant, les composants et les sous-systèmes micro-ondes basés sur la technologie GIS ont été largement étudiés et développés. Dans cette thèse, nous étudions d’avantage la technologie GIS afin de proposer et développer divers composants actif et passif micro-ondes et millimétriques innovant et originaux. Ces structures de composants innovants peuvent améliorer l’intégration entre les composants GIS et les autres composants planaires. Ainsi, un certain nombre de structures et composants sont proposés et appliqués dans la conception et la démonstration d’un réseau d’antennes intégré en ondes millimétriques et un sous-système d’antennes intelligentes à 60 GHz. Il est à noter que plusieurs composants étudiés dans ce travail ont été proposés et démontrés à des fréquences micro-ondes plus basses afin de faire une preuve de concept en permettant une fabrication facile des structures et des circuits. Ces circuits en basses fréquences peuvent facilement être adaptés pour des applications aux fréquences plus hautes.---------- ABSTRACT The tendency of modern microwave and millimetre-wave communication system development is towards small size, light weight, reliable, multifunctional and low-cost. Moreover, low-cost, mass producible, high-performance and high-yield microwave and millimetre wave technologies are crucial for developing successful commercial microwave and millimetre wave systems. Rectangular waveguide has always been among the most popular choices for the making of millimetre-wave circuits and systems. A major challenge, however, is related to its integration with active devices and other conventional planar transmission lines, such as microstrip or coplanar waveguide (CPW), etc. Substrate Integrated Circuits (SICs) techniques including substrate integrated waveguide (SIW), which can be integrated in planar dielectric substrate with low insertion loss, high Q and low radiation loss, present a family of novel guided wave structures. This scheme provides a bridge between planar and non-planar structures. Up to now, microwave components and sub-systems based on SIW technology have been widely studied and developed. In this thesis, we take a further study of SIW technology to propose and develop various innovative and original microwave and millimetre-wave passive and active components. These innovative component structures can improve the integration between SIW components and other planar components. Then, a certain number of proposed structures or components are applied in the design and demonstration of millimetre-wave integrated antenna arrays and 60 GHz smart antenna sub-system. Note that many components studied in this work were proposed and demonstrated at different lower microwave frequencies for the proof of concept purpose with easy-to-fabricate structures and circuits. Those low-frequency circuits can easily be scaled up for high-frequency applications

The Concept of Substrate Integrated E-plane Waveguide and Circuits

In this thesis, a new type of substrate integrated waveguide is proposed for implementing E-plane type of waveguide circuits on printed circuit boards. obviously, these E-plane type of circuits cannot be realized by the conventional substrate integrated waveguide. The so-called substrate integrated E-plane waveguide consists of two circuit boards attached to each other. Two copper strips are inserted in between two circuit boards, where plated through holes are penetrated through them along the transmission direction. The plated through holes and copper strips altogether played as side walls of a conventional waveguide to support longitudinal and vertical currents. Simulation is carried out and the result shows that the proposed waveguide is able to guide horizontally polarized electromagnetive wave. An E-plane inductive septa filter, two one-dimensional E-plane offset waveguide filters, and an air-filled evanescent-mode band-pass filter are proposed as examples to prove that E-plane type of circuits are able to be built based on this new synthesized waveguide structure

Antenna Design for 5G and Beyond

With the rapid evolution of the wireless communications, fifth-generation (5G) communication has received much attention from both academia and industry, with many reported efforts and research outputs and significant improvements in different aspects, such as data rate speed and resolution, mobility, latency, etc. In some countries, the commercialization of 5G communication has already started as well as initial research of beyond technologies such as 6G.MIMO technology with multiple antennas is a promising technology to obtain the requirements of 5G/6G communications. It can significantly enhance the system capacity and resist multipath fading, and has become a hot spot in the field of wireless communications. This technology is a key component and probably the most established to truly reach the promised transfer data rates of future communication systems. In MIMO systems, multiple antennas are deployed at both the transmitter and receiver sides. The greater number of antennas can make the system more resistant to intentional jamming and interference. Massive MIMO with an especially high number of antennas can reduce energy consumption by targeting signals to individual users utilizing beamforming.Apart from sub-6 GHz frequency bands, 5G/6G devices are also expected to cover millimeter-wave (mmWave) and terahertz (THz) spectra. However, moving to higher bands will bring new challenges and will certainly require careful consideration of the antenna design for smart devices. Compact antennas arranged as conformal, planar, and linear arrays can be employed at different portions of base stations and user equipment to form phased arrays with high gain and directional radiation beams. The objective of this Special Issue is to cover all aspects of antenna designs used in existing or future wireless communication systems. The aim is to highlight recent advances, current trends, and possible future developments of 5G/6G antennas

Advances in Filter Miniaturization and Design/Analysis of RF MEMS Tunable Filters

The main purpose of this dissertation was to address key issues in the design and analysis of RF/microwave filters for wireless applications. Since RF/microwave filters are one of the bulkiest parts of communication systems, their miniaturization is one of the most important technological challenges for the development of compact transceivers. In this work, novel miniaturization techniques were investigated for single-band, dual-band, ultra-wideband and tunable bandpass filters. In single-band filters, the use of cross-shaped fractals in half-mode substrate-integrated-waveguide bandpass filters resulted in a 37 percent size reduction. A compact bandpass filter that occupies an area of 0.315 mm2 is implemented in 90-nm CMOS technology for 20 GHz applications. For dual-band filters, using half-mode substrate-integrated-waveguides resulted in a filter that is six times smaller than its full-mode counterpart. For ultra-wideband filters, using slow-wave capacitively-loaded coplanar-waveguides resulted in a filter with improved stopband performance and frequency notch, while being 25 percent smaller in size. A major part of this work also dealt with the concept of 'hybrid' RF MEMS tunable filters where packaged, off-the-shelf RF MEMS switches were used to implement high-performance tunable filters using substrate-integrated-waveguide technology. These 'hybrid' filters are very easily fabricated compared to current state-of-the-art RF MEMS tunable filters because they do not require a clean-room facility. Both the full-mode and half-mode substrate-integrated waveguide tunable filters reported in this work have the best Q-factors (93 - 132 and 75 - 140, respectively) compared to any 'hybrid' RF MEMS tunable filter reported in current literature. Also, the half-mode substrate-integrated waveguide tunable filter is 2.5 times smaller than its full-mode counterpart while having similar performance. This dissertation also presented detailed analytical and simulation-based studies of nonlinear noise phenomena induced by Brownian motion in all-pole RF MEMS tunable filters. Two independent mathematical methods are proposed to calculate phase noise in RF MEMS tunable filters: (1) pole-perturbation approach, and (2) admittance-approach. These methods are compared to each other and to harmonic balance noise simulations using the CAD-model of the RF MEMS switch. To account for the switch nonlinearity in the mathematical methods, a nonlinear nodal analysis technique for tunable filters is also presented. In summary, it is shown that output signal-to-noise ratio degradation due to Brownian motion is maximum for low fractional bandwidth, high order and high quality factor RF MEMS tunable filters. Finally, a self-sustained microwave platform to detect the dielectric constant of organic liquids is presented in this dissertation. The main idea is to use a voltage- controlled negative-resistance oscillator whose frequency of oscillation varies according to the organic liquid under test. To make the system self-sustained, the oscillator is embedded in a frequency synthesizer system, which is then digitally interfaced to a computer for calculation of dielectric constant. Such a system has potential uses in a variety of applications in medicine, agriculture and pharmaceuticals