The project investigates the Cavity Perturbation Method (CRM) and design of a coaxial resonator covering a wide frequency band from 2.5 to 11.5 GHz. Using the published analyses for coaxial cavities, original theoretical analysis of Cavity Perturbation Method for TEM coaxial cavity was carried out by the author. Using similar approach, the H(_011) cylindrical cavity was analyzed. The deliberate objective of the method was to produce a wide band technique since there are none available at present. The method then examines the possibility of employing the coaxial cavity as an important and necessary measuring device for dielectric measurements using CPM. It was the aim in the investigations to state clearly what assumptions were made so that the accuracy of the calculated results could be assessed. A new measurement technique, using a Sweep Generator/ Spectrum Analyzer Assembly (SG/SA) was introduced. The technique is based on very precise measurements of the changes in cavity Q and its resonant frequency, displayed on Spectrum Analyzer, when the test sample of the material is inserted. Because the main objective of the project is the method of measurements, the assessment of its validity and accuracy was fully discussed. Measurements were carried out on fifteen materials of various types of ceramics over the frequency range of interest. These materials were used mainly for the assessment of the validity and accuracy of the new Sweep Generator/Spectrum Analyzer Assembly technique, and also a test of the capability of the constructed broadband coaxial cavity to be used for dielectric measurements. The well-known Bridge and Q-meter methods, were employed initially to provide the low frequency values for the materials as reference. An attempt has also been made to justify the validity of the universal law on those materials. Additional work not directly related to the main project has been carried out on Curie temperature measurements. The object was to develop a simple and reliable method using the Gouy balance technique.

Abstract In the first part of this study, determination of the dielectric properties of the low loss microwave ceramic material, barium nonatitanate (Ba2Ti9O20), around 1 GHz is discussed. The structures under test were coaxial resonators, the cores of which were made of barium nonatitanate and the metallization was realised by thick film silver. The measured value of the real part of the relative dielectric constant was εr = 37 and that of the loss tangent was tan σ = 0.00014. The change of the resonance frequency of the coaxial resonators with temperature, in the range -20 … +80 C, was 4 ppm/ C. In addition, realisation of compact interdigital and comb-line bandpass filters was demonstrated for the 900 MHz mobile phone band. Besides Ba2Ti9O20, Ba(Sm,Nd)2Ti5O14 ceramic material with a dielectric constant of εr = 78 was also employed in order to improve the miniaturisation. The volume of the smallest filter was 2 cm3 and the weight was 9 g. In the second part of this study, various measurement methods have been demonstrated to determine the real part of the relative permittivity of FR4 fibreglass circuit board. Test structures were straight asymmetric open-circuited strip lines. It was found that the real part of the relative permittivity decreased slightly with frequency. At 0.72 GHz and 4.5 GHz, εr values of 4.3 and 4.1, respectively, were measured. All the characterisation methods used gave consistent values for εr, and electromagnetic simulators were used to verify the results. In the third part of this study, the structures under test were microstrip or strip line transmission lines, the S parameters of which were measured by using on-wafer measurement techniques. It was found that the insertion loss of the 10 mm long etched Cu microstrip was slightly less than that of the Ag microstrips which were manufactured by etching and gravure offset printing techniques, respectively. The performance of the Ag microstrips was, however, similar. In addition, a theoretical basis was established for the determination of εr of the dielectric substrate and the attenuation coefficient of the transmission lines under test. The calculations were based on signal flow diagrams. The method was applied to determine the dielectric and loss properties of a commercial, Kyocera, Japan, LTCC (Low Temperature Cofired Ceramic) material up to 50 GHz. The measured value of the real part of the relative permittivity was εr = 5.7, and the loss tangent was approximately tan σ = 0.003. The essential idea behind the studies reported in this thesis was twofold. First, the studies aimed at characterising dielectric media which find usage in the realisation of UHF, microwave or millimetre wave circuits. Second, the studies aimed to obtain data of immediate value in practical design work. For this reason, the structures under test were transmission lines having extensive usage in practical high frequency circuit design.

The limit of current technology for mobile base station filters is the multimode filter, in which each cavity supports two (or possibly three) independent degenerate resonances. Shielded dielectric resonators with a rectangular cross-section are useful in this application. In the design of these filters, manufacturers are using software packages employing finite element or finite difference time domain techniques. However, for sufficient accuracy these procedures require large numbers of points or elements and can be very time consuming. Over the last decade research using the mode matching technique has been used to solve this kind of difficulty for various types of filter design and waveguide problems. In this thesis a mode matching method and computer program is developed to calculate the propagation coefficients and field patterns of the modes in a shielded rectangular dielectric rod waveguide. Propagating, complex, evanescent and backward wave modes are included and the work shows the presence of a dominant mode, and other fundamental modes, not previously identified. The effect of the shield proximity on the propagation characteristics and mode spectrum is investigated, together with the limitations on the accuracy of the mode matching method. In addition, the fields within the shielded rectangular dielectric rod waveguide, are used to calculate the attenuation coefficient of the dominant and fundamental modes. The influence on the attenuation coefficient of the proximity of the shield to the rod is also evaluated for these modes and limitations on accuracy are discussed. The calculated numerical results for the propagation and attenuation coefficient values are verified by measurement. The propagation coefficients results are typically within 2% of those measured. Verification of the attenuation coefficient results is achieved by comparing calculated and measured Q at the resonant frequencies of a number of shielded rectangular dielectric rod resonators. The difference between calculated and measured Q values is on average less than 4%. In the absence of a full solution of the shielded rectangular dielectric rod resonator, these results provide useful design information for this structure. In addition, the work reported in this thesis provides a basis for a full electromagnetic solution of this type of resonator. This would encompass the cubic dielectric resonator in a cubical cavity.

Thesis (MScEng)--Stellenbosch University, 2011. / ENGLISH ABSTRACT: The purpose of this project is to develop a number of coaxial resonator lters. Firstly, the theoretical model of the lter is discussed, with a Tchebyscheff LC-ladder prototype lter used to derive a generalised bandpass lter. From this, generalised Combline- and Interdigital lters are derived. Following this, various options and limitations in the mechanics of microwave lters are discussed. Results are shown for an in-depth study considering the unloaded quality factor for thirteen di erent resonators. Each resonator is unique in the method of manufacturing, polishing, as well as plating. Utilizing the information obtained from the unloaded quality factor measurements, three coupled coaxial resonator lters, are designed for use in a radar system, namely a sixth order 2125 MHz Combline lter, a sixth order 9250 MHz Interdigital lter and a third order 9250 MHz Interdigital lter. Optimal results were obtained when both resonators and coupled transmission line lters were constructed from aluminium that was wire-cut and then silver electroplated. / AFRIKAANSE OPSOMMING: Die omvang van hierdie projek behels die ontwerp en bou van ko-aksiale resoneerder filters. Eerstens word die teoretiese modellering van die lters bespreek. 'n Tchebyscheff LC-leer prototipe filter word gebruik as basis vir 'n generiese banddeurlaat filter. Die banddeurlaat lter word gebruik om die afgeleide Kamlyn- en Interdigitale filter te de finieer. Hierna volg 'n bespreking aangaande die verskillende moontlikhede in die meganiese vervaardiging van mikrogolf filters. 'n Gedetailleerde studie word gedoen om die onbelaste kwaliteitsfaktore van 13 verskillende resoneerders te bepaal. Elkeen van hierdie resoneerders is uniek in die metode van vervaardiging, polering, asook die platering daarvan. Deur gebruik te maak van die resultate van die onbelaste kwaliteitsfaktore, word drie gekoppelde ko-aksiale resoneerder filters ontwikkel vir die gebruik in 'n radarstelsel, naamlik 'n sesde-orde 2125 MHz Kamlyn lter, 'n sesde orde 9250 MHz Interdigitale filter, asook 'n derde orde 9250 MHz Interdigitale filter. Die beste resultate was gevind toe beide resoneerders en gekoppelde ko-aksiale resoneerder filters vervaardig is uit aluminium wat gedraadsny en silwer geplateer is.

International Telemetering Conference Proceedings / October 28-31, 1996 / Town and Country Hotel and Convention Center, San Diego, California / In this paper design and development of a PC- Based S- Band Down Converter/ FM Telemetry Receiver are discussed. With the advent of Direct Digital Synthesis (DDS) & Phase Locked Loop (PLL) technology, availability of GaAs & Silicon MMICs, Coaxial Resonator Oscillator (CRO), SAW Oscillator, SAW Filters and Ceramic Filters, realisation of single card PC- Based Down Converter and Telemetry Receiver has become a reality. With the availability of Direct Digital Synthesis and Phase Locked Loop devices having microprocessor bus compatibility, opens up many application in Telemetry and Telecommunications. In this paper design of local oscillator based on hybrid DDS & PLL technique, Coaxial Resonator Oscillator and Front-end are discussed in detail.

Le résonateur matriochka est conçu à partir de résonateurs coaxiaux ré-entrants créant ainsi des sauts d’impédances (SIR). La thèse développe alors des innovations théoriques sur la technologie matriochka en proposant des modèles analytiques précis sur le comportement fréquentiel et du facteur de qualité du résonateur. Les modélisations mettent en relief l’existence de degrés de liberté au sein du résonateur matriochka induisant une flexibilité du rapport de forme du résonateur. Les degrés de liberté créent ainsi une multitude de configurations du résonateur matriochka pour une fréquence fondamentale et un facteur de qualité donnés. Par conséquent, une optimisation en volume est réalisée pour concevoir deux filtres en bande L et C afin de minimiser leur encombrement. Une étude de la tenue en puissance dans le vide est également effectuée pour le filtre en bande L. Une méthode conjointe d’optimisation de la tenue en puissance et de minimisation en volume est alors proposée pour ce filtre. Ainsi, les modélisations et les optimisations sont employées afin de concevoir et de fabriquer deux filtres hyperfréquences. Le premier est un filtre de transmission en bande L conçu pour l’application de navigation Galileo qui propose une alternative d’encombrement et une tenue en puissance dans le vide élevée. Enfin, le second est un filtre de réception en bande C conçu, fabriqué et mesuré pour l’application de télémesure qui propose de meilleures performances en réjection et un volume réduit par rapport à l’existant. Finalement, la technologie matriochka est une alternative de résonateur par rapport à l’état de l’art en proposant, selon les configurations, un rejet élevé des harmoniques et un volume réduit pour une fréquence fondamentale et un facteur de qualité donnés. / The matriochka resonator is based on reentrant coaxial Stepped Impedance Resonator (SIR). So, the thesis develops theoretical innovations on the matriochka technology offering accurate analytical models on the frequency and the quality factor behaviors of the resonator. The models prove the existence of degrees of freedom within the matriochka resonator which allows to get different form factors of the resonator. The degrees of freedom create many configurations of the matriochka resonator for a fundamental frequency and a quality factor. Consequently, a volume optimization is realized to design a L-band filter and a C-band filter. A multipactor study is also carried out for the L-band filter. So, a joint optimization method of the multipactor and the volume minimization is proposed for this filter. Thus, the models and optimisations are used in the order to to design and fabricate the microwave filters. The first one is a transmission L-band filter for the navigation application Galileo which offers a volume alternative and a high power in the vaccum. Then, the second one is a reception C-band filter for the telemetry application which offers wide spurious free-performance and a low volume compared to the state of the art. Finally, for a frequency and a quality factor and depending on the configurations, the matriochka technology offers an alternative of the resonator volume, and it offers a wide spurious free- performance and a low volume compared to the state of the art.