Dissertations / Theses on the topic 'Microstrip Ring Resonator'

碩士<br>國防大學中正理工學院<br>電子工程研究所<br>91<br>In this thesis, the Double-Ring filter is proposed to improve the bandwidth of conventional ring filters. The possibility of the Double-Ring filter will be verified by measurements and simulations. The mode coupling techniques of the Double-Ring resonator can be classified as two types: (1) The Directive coupled-mode, (2) The Cross coupling-mode. Both of Double-Ring filter and Extended Double-Ring filter belong to the Directive coupled-mode. By the measurements and simulations the possibility of the mode coupling techniques can be verified. By this contribution the Double-Ring filter and the Extended Double-Ring filter all have the characteristic of pass-band. In the experiment design, we can fit the filter by the techniques of adjusting values, bridging capacitance and cascade-stage, and it can be served as a reference for Double-Ring filter design. From the matching techniques, the Double-Ring filter is designed and compared with Butterworth filter, Single-Ring filter and Chebyshev filter for the advantages. The measurements and the simulations are similar.

碩士<br>國立交通大學<br>電信工程系所<br>93<br>An optimal ring resonator and a new square loop resonator are proposed for designing miniaturized dual-mode bandpass filters. In the first resonator, the center of each side of the loop resonator is tapped with a capacitive arrow-shape open stub. The whole resonator encloses four coupled compact miniaturized hairpin resonators. The slow-wave effect caused by the capacitively load can reduce the fundamental frequency of the loop resonator. As a result, this miniaturized loop resonator can be used to synthesis a miniaturized dual-mode bandpass filter. In the second resonator, the fundamental frequencies and higher order resonant harmonics of ring resonators with different numbers of impedance steps are analyzed against the length and impedance ratios of the hi-Z and low-Z segments. It is found that the optimal numbers of impedance steps and length can be obtained for a given hi-Z to low-Z impedance ratio to minimize the filter size and maximize the upper rejection bandwidth. Both the proposed bandpass filters not only have good spurious-free performances, but also achieve more than 50% size reductions, as compared with a conventional dual-mode ring bandpass filter. The measured results show a good match with the simulated responses.

碩士<br>國立交通大學<br>電信工程系所<br>95<br>Coupled-line stages are designed with corrugated periods to accurately allocate inherent transmission zeros at three leading even harmonics of design frequency, fo. The corrugation is finely trimmed so that the eigenmode phase velocities at these frequencies can be equalized. Through adjusting number of corrugation periods of a stage, frequencies of the zeros can be arbitrarily scaled up to a certain extent. In this way, a parallel-coupled line bandpass filter with a cascade of several such stages can be synthesized to be free of spurious harmonics up to at least 10fo, with aid of tapped input/output coupling scheme. The spurious harmonics from 11fo to 16fo are further suppressed by bandstop characteristics of periodic structure. The measured data of the fabricated bandpass filter show a rejection level of better than 30 dB in the upper stopband up to 18fo. Double-ring resonator with two open stubs is proposed to design quadra-mode bandpass filters. Two open stubs are horizontally attached to the inner ring. By appropriately adjusting the length or width of stubs, it is possible to control an extra zero existing in the double-ring structure. In addition, perturbation patches are introduced to inner and outer rings to split up the four poles for synthesizing a bandpass filter with high selectivity and relatively wide passband. In order to validate the proposed idea, two quadra-mode bandpass filters with fractional bandwidth of 10% and 15% are fabricated. Measured results show that the in-band insertion losses are less than 1.1dB. Simulation data are also plotted for comparison.

In this study, a novel and systematic methodology for the design and optimization of lowpass filters (LPFs), and multiorder-bandpass filters (BPFs) are proposed. The width of the LPF signal traces consistently follow Fourier truncated series, and the thickness of the substrate as well. By studying different lengths and other physical constraints, the design meets predefined electrical requirements. Moreover, superformula is used in split ring resonators (SRRs) designs to obtain a BPF response and significant structural compactness. Non-uniform transmission lines, as well as superformula equations, are programmed in MATLAB, which is also used for analytical validations. Traces are drawn in AutoCAD. The substrate of LPF is constructed in Pro/e. Finally, the optimized layouts are imported to Ansys High Frequency Structure Simulation (HFSS) software for simulation and verification. Nonuniform LPFs are optimized over a range of 0-6 GHz with cutoff frequency 3.5 GHz. Superformula implemented multiorder-BPFs are optimized with cutoff frequency of 1.1 GHz.

碩士<br>國立中央大學<br>通訊工程研究所<br>94<br>Abstract In the thesis, the design of the microstrip ring resonators is discussed, and new feeding strategies are proposed. Due to a variety of resonators employed in circuit design, the feeding(or energy-coupling) strategy is always an important issue. Thus, a better coupling strategy will be applied and the size of the circuit configuration will be improved at the same time in the thesis. The full-wave electromagnetic simulator, IE3D, will be used in the design. Circuits will be realized using FR4 printed-circuit boards. The design will be validated by the comparison with experimental results.

碩士<br>長庚大學<br>電子工程學研究所<br>97<br>In general, RF wireless signals transit in atmosphere. In order to reject unwanted radio waves or noises, a band-pass filter can be used to reject noise in stopband. Therefore, this paper presents two kinds of band-pass filter. The first one is an asymmetrical response band-pass filter with three transmission zeros, the design principle uses traditional π-network of second-order band-pass filter inductively coupled combining of capacitance to ground and coupling capacitance mechanisms to achieve the two lower bands and upper band zeros. The most important thing is that this mechanism of cross coupling capacitance does not affect the passband performance .The measured insertion loss of the passband is less than 3dB, and three transmission zeros of less than -20dB attenuation at 10GHz, 16.7GHz and 60GHz. Second type of filter is dual-mode ring resonator, which has advantages of simple structure, easy implementation, and two transmission zeros at upper and lower. In Chapter III, we selected this simple symmetrical structure with high-quality dual-mode ring resonator as a filter. Using multi-layer metal process of TSMC 0.18μm CMOS to make sandwich MIM structure as the feed and perturbation capacitor, it can easily adjust the input and output ports of the feed location, and using a smaller area to achieve sufficient coupling to match the circuit. Also, we make analysis for the perturbation impact of transmission zeros and bandwidth. Besides, the ring resonator is also combined with multi-layer metal, by changing the characteristic impedance of microstrip line to increase flexibility of circuit design to get the better pass-band and stop-band characteristics. Finally, we implement a successful operation in the 60GHz dual-mode ring bandpass filter, and meander the ring to reduce the area of 40 percent, the overall area of 0.56 × 0.73 mm2, insertion loss is less than 4dB, transmission zeros at 46GHz and 88GHz get the attenuation lower than -20dB. In Chapter IV, we use the design method shown in Chapter III to make a dual-mode dual-band bandpass filter in the pHEMT process which provided by semiconductor companies WIN. 60GHz is unlicensed band which can find applications in such as point-to-point wireless LANs and broadband internet access.77GHz is another unlicensed band for adaptive cruise control on cars. The measurement conform both of the 60GHz and 77GHz frequency bands of specification. Insertion loss of passband are less than 3dB, there is more than -30dB attenuation zeros located at 51, 70, and 91GHz. Those results fit the specification of 60 and 77 GHz systems. The total area is 0.91×0.46 mm2. Index Terms: Bandpass filter、transmission zero、dualband filter、dual-mode ring resonator

碩士<br>國立交通大學<br>電信工程研究所<br>100<br>In this thesis, we proposed miniaturization bandpass filters (BPFs) design based on complementary split ring resonators (CSRRs) with two different operating frequency. The two BPFs are operated at 2.45 GHz and 1.85 GHz, respectively. The complementary split ring resonator, which is one kind of the meta-material, since it has unique electromagnetic characteristics, therefore there are many academic literatures about CSRRs which are applied on miniaturization of antennas and microwave circuits. In the first part of this thesis, a BPF is implemented by utilizing CSRRs and microstrip line coupled interdigital-capacitors to realize necessary circuit components. The open stubs are used to improve the selectivity of the higher edge of the passband, and we proposed the equivalent circuit to explain the frequency responses which are affected by the parts of the BPF. In the last part of this thesis, we use the proposed BPF to design the compact size microstrip diplexer. By simulation and measurement results, the diplexer has good characteristic responses, such as transmission loss (1.1 dB and 1.4 dB),signal suppression (29.6 dB and 41.21 dB),and 3 dB fractional bandwidth (12.85% and 8.91%). Moreover, the diplexer occupy a small area and has the dimensions of 51 mm×29 mm about 0.42λg × 0.2λg.

碩士<br>樹德科技大學<br>電腦與通訊研究所<br>94<br>In the RF communicative world, the quality of wireless signals is key factor. The filters are a kind of important component application in the RF field. In this thesis, we used the physics technique “Split Ring Resonators (SRRs)” which is based on the “Dual –Mode Ring Resonator” structure application of RF filters, and suppressed the second harmonic successfully. Using the technique of Split Ring Resonators had many advantages. In this research we found the Split Ring Resonators were designed easily in many structures and didn’t change the major structure. The result of the Split Ring Resonator’s work could suppress the second harmonic in 1.0 GHz to 10.0 GHz and didn’t change the major frequency.

碩士<br>大葉大學<br>電機工程學系<br>99<br>This paper presents an accurate design technique for a low-pass filter with complementary split-ring resonators (CSRR).We extract the complementary split-ring resonators (CSRR) equivalent circuit component values for designing filter.The CSRR not only can significantly increase the characteristic impendance of microstrip line,but also improve stopband performance by rejecting the higher order passband.For increasing efficiency and reducing the area of circuits, we usually utilize the defected ground structure, but the conventional design did not consider the parasitic effect of stub at high frequency﹒The parasitic effect may result in significant frequency deviation.In order to improve the accuracy of the low pass filter design with CSRR, an equation to find the parasitic inductance is suggested.This inductance is used to modify the frequency deviation of low pass filter.

博士<br>國立交通大學<br>電子物理系所<br>94<br>Superconducting microstrip ring and line resonators were successfully fabricated using double-side YBa2Cu3O7-δ (YBCO) and Y0.7Ca0.3Ba2Cu3O7-δ (Ca-YBCO) thin films deposited on LaAlO3 (LAO) substrates by pulsed laser deposition. By controlling the oxygen contents of the same resonator, the hole concentration p determined from the empirical relation, Tc/Tc,max=1-82.6(p-0.16)2, was controlled from the over- to the underdoped regime. The microwave surface impedance measurements, Zs(T) = Rs(T) + jXs(T), allow us to determine the complex conductivity, ��(T), in the ab-plane of YBCO and Ca-YBCO thin films. Using results of Zs(T) and ��(T) together with the modified two-fluid model, the doping and temperature dependences of London penetration depth, superfluid density and complex conductivity can be systematically studied. In particular, these experimental results can be used to test the current theoretical models of high-Tc superconductivity, especially for Lee’s model, Wen and Lee’s model, Emery and Kivelson’s model and Vishveshwara and Fisher’s model. Some salient results found in the dissertation are listed below: I. From the measurements of the temperature dependence of resonance frequency in the microstrip ring and line resonators, the absolute values of the ab-plane London penetration depth at 5K were obtained for YBCO and Ca-YBCO thin films with various hole concentrations by using Chang’s formula together with the help of THz measurements. For example, was obtained to be at optimum doping, and this result was consistent with the one obtained from single crystal measurement ( ) or thin film measurement ( ). II. In the underdoped regime, the measured superfluid density is proportional to critical temperature Tc. This relation has been revealed by the Uemura relation. However, for all doping levels (from over- to underdoped regime), the measured superfluid density is proportional to the product of critical temperature (Tc) and the d.c. conductivity at Tc. This universal relation can be explained by using Ferrell-Glover-Tinkham (FGT) sum rule. Furthermore, the doping dependence of the normalized superconducting energy gap can be obtained from the FGT sum rule. Compare to the doping dependence of the superconducting d-wave gap directly measured by scanning tunneling spectroscopy (STS), the doping dependence of is consistent with that measured by STS. This indirect evidence not only leads further support that the superconducting energy gap is of d-wave symmetry but also point out that the charge is conserved in the ab-plane of the cuprates. III. The complex conductivity �� = ��1 - j��2 extracted from experiments together with the help of some theoretical model gives the evidence that the real part of complex conductivity, ��1, and the imaginary part of it, ��2, both have thermal activation gap. This result is consistent with the prediction of Lee’s model. It thus points out that the classical thermal fluctuations play an important role on physical properties of the high temperature state of high-Tc superconducting cuprates. Also, by fitting ��2 with , it was found that a characteristic energy scale emerges. is higher than Tc, when . The phase diagram of versus hole concentration p is similar to that predicted by Emery and Kivelson’s model. Hence, we propose that would be the upper bound on the phase ordering temperature in the underdoped regime, and in the overdoped regime, is corresponding to the mean field transition temperature . IV. There are two cases for the temperature dependence of ��1 in the low temperature regime (T < 0.1 Tc). Case 1, ��1(T) reaches a plateau in the low temperature limit. Case 2, ��1(T) decreases with temperature in the low temperature limit. However, in both cases, ��1(T) contains a thermal activation gap . The meaning of the thermal activation gap in ��1(T) can be attributed to the energy barrier for quasiparticle tunneling in the weak-link structures. And also, in case 1, the cuprate is the thermal insulator in the superconducting state according to the Vishveshwara and Fisher’s model. But for case 2, the real part conductivity ��1(T) contains an extra linear-T contribution, which has been also observed for pure crystals, as reported by Hardy et al. We propose that the linear-T contribution is due to the delocalized quasiparticles free from the effects of weak links. According to Vishveshwara and Fisher, the delocalized quasiparticles would further result in the thermal metal phase in the superconducting state. Thus, for case 2, the ��1(T) results imply that there are two phases, the thermal-metal and the thermal-insulator, in the superconducting state of some samples displaying the clean limit behaviors similar to those observed in high purity single crystal. The fact reveals that the feature of is very sensitive to the degree of disorder in the cuprate samples. V. As the temperature approaching 0 K, ��1(T) has a finite residual value, which we denoted as ��1(5K). According to Lee’s model, impurity scattering, particularly in the unitary limit, produces low energy quasiparticles in a two-dimensional d-wave superconductor even with small impurity concentrations. In our thin film samples, these quasiparticles are localized because the mean free path of quasiparticles ( ) is smaller than the localization length ( ). In this condition, the conductivity ��1(T) approaches to a universal value at , where is the coherence length and is the lattice constant. Moreover, Durst and Lee proposed a theoretical model based on Lee’s model that the universal value should be corrected by the Fermi liquid correction factor ��2 and the vertex correction factor , which accounts for the charge current renormalization and anisotropic impurity potential, respectively. Based on the residual conductivity ��1(5K) obtained in our experiments, we found that the value of is about 1.5±1.0, which is consistent with that predicted by the Durst and Lee’s model. In fact, we have observed that a flattening of the temperature dependence of in the low temperature limit, which is also consistent with that predicted by Lee’s model. All of these results revealed that the quasiparticles have the tendency of being localized in a two-dimensional superconductor with small impurity concentrations or disorder. VI. The Fermi-liquid model, proposed by Wen and Lee in 1998 to describe the basic nature of low-lying excitations, was analyzed in a quantitative manner. The obtained Fermi-liquid correction factor, ��, was formed to be always smaller than one ( ) over the entire doping range (from underdoped to overdoped) and is almost independent of hole concentration p, which is consistent with that predicted by Wen and Lee’s model ( ). The results revealed that the basic nature of quasiparticles in the superconducting state can be attributed to the normal Fermi-liquid in all doping levels. VII. The imaginary part of complex conductivity ��2(T) has a thermal activation gap , which shows the thermal-averaged Josephson coupling energy of superfluid (Cooper pairs) in forming the long range order across the barriers macroscopically. VIII. A closed form of the empirical formula of the real part and the imaginary part is obtained respectively. From that, the phase diagram of several energy scales versus hole concentration p was presented. The phase diagram is very similar to the one predicted by Emery and Kivelson’s model based on the classical phase fluctuations on explaining the Cooper pair formation for high-Tc superconductors. We conjecture that the formation of superconducting state in the high-Tc superconducting thin films is owing to the phase fluctuations mechanism. The experimental results have revealed that a number of the basic natures of quasiparticles in the superconducting state can be attributed to the normal Fermi liquid in the all levels of doping. When T > Tc, the classical phase fluctuations play a key role in forming the Cooper pairs of short range order. When T �� Tc, the superconductivity with a long range order is formed by the Josephson tunneling of superfluid (Cooper pairs). In the superconducting state (T < Tc), the ��2(T) was attributed to the effect of Josephson tunneling in the weak links in our disordered samples. However, for all of the experiments in the microwave measurements till now there are two cases for ��1(T). One of them is that ��1(T) can be completely attributed to the effect of quasiparticle tunneling in the weak links. It means that the quasiparticles are localized, and ��1(T) is in thermal insulator phase in the superconducting state. Another is that ��1(T) can be partly attributed to the effect of quasiparticle tunneling through the weak links, i.e. quasiparticles are localized, and partly attributed to the effect of delocalized quasiparticles. In this case, ��1(T) indicates that the system contains both the thermal insulator and the thermal metal phases. All of the above results have led us to the conjecture that in the HTSC, there are two different energy scales which correspond to two temperatures: Tc below which coherence is established, and some higher temperature where the pairs are formed. These two scales are close to each other, in the all levels of doping. The conjecture is also to endow the two associated superconducting phases - the thermal metal and the thermal insulator – and the critical point between them.