Active and Passive Microwave Devices and Circuits

Recent applications of CRLH unit cells used to design distributed passive and active microwave devices and circuits are presented. In particular, new configurations for small-size passive devices based on quarter-wavelength transmission line sections, as well as microwave amplifiers, oscillators and frequency doublers are analyzed. The performances of these new circuit topologies are put into evidence numerically and the results are validated by experiments.

Design of a metamaterial based on an S-shaped resonator surrounded by a ground frame and excited by using a feeding transmission line on microstrip technology is presented. Since the resonator, ground frame, and its excitation mechanism are all realized on a microstrip, its characterization can be carried out using common laboratory equipment without needing any waveguide components or plane-wave-illumination techniques. The structure presented here may be realized on any microstrip and does not require special materials. The resonator and ground frame are both on the same side of the microstrip, thus the proposed topology may also be populated with active and passive microwave components, and hybrid active, passive, or reconfigurable microwave circuits may be realized. In metamaterial designs that require plane wave illumination, usually many numbers of periodic unit cells are needed; however, in our design, only one cell is capable of achieving metamaterial properties. The constitutive parameters of the metamaterial are retrieved and compared to demonstrate the agreement between simulations and measurements. The proposed topology is also demonstrated in a sensor application, where simulated and measured results agree well. Thus, it can be realized using standard microwave technology and used for numerous applications where metamaterial properties are needed.

<p><span>Nowadays, the world knows a huge revolution in telecommunications, which has led to the need to integrate many services, such as long-term evolution (LTE), 5G, wireless local area network (WLAN), and Bluetooth, in one receiving and transmitting device. In the same way, all active and passive microwave circuits must be compatible with the integration of services, including the power divider, which is the subject of our work. This passive component is used in several fields such as medicine, surveillance, radar systems and others applications. Wilkinson divider is one of the most prominent power dividers, it is classified as narrow-band power divider and it is a very useful component in mobile applications (2.4 and 5.8 GHz). In this work, a reconfigurable 4-ports Wilkinson divider is designed using PIN diodes and simulated using connected speech test (CST) simulator software. This designed divider can easily modify the operation mode by activating or disabling the PIN diodes.</span></p>

This paper proposes an extension of the unconditionally stable finite-element time-domain (FETD) method for the global electromagnetic analysis of active microwave circuits. This formulation has two advantages. First, the time-step size is no longer governed by the spatial discretization of the mesh, but rather by the Nyquist sampling criterion. Second, the implementation of the truncation by the perfectly matched layers (PML) is straightforward. An anisotropic PML absorbing material is presented for the truncation of FETD lattices. Reflection less than -50 dB is obtained numerically over the entire propagation bandwidth in waveguide and microstrip line. A benchmark test on a microwave amplifier indicates that this extended FETD algorithm is not only superior to finite-difference time-domain-based algorithm in mesh flexibility and simulation accuracy, but also reduces computation time dramatically.

In this paper, the spoof surface plasmon polaritons (SSPPs) transmission line (TL) of periodical grooved bow-tie cells is proposed. The complex propagation constant and characteristic impedance of the SSPPs TLs and microstrip lines (MLs) are extracted using the analytical method of generalized lossy TL theory. The properties of the SSPPs TLs with different substrates and the same geometrical configuration are experimented. Then, for comparison, two ML counterparts are also experimented, which shows that the SSPPs TL is less sensitive to the thickness, dielectric constant and loss tangent of the chosen substrate below the cutoff frequency, compared with the ML ones. The single-conductor co-planar quasi-symmetry unequal power divider based on this SSPPs TL is presented in microwave frequencies. For experimental validation, the 0-dB, 2-dB, and 5-dB power dividers are designed, fabricated, and measured. Both simulated and measured results verify that the unequal power divider is a flexible option, which offers massive advantages including single-conductor co-planar quasi-symmetry structures, wide-band operation, and convenient implementations of different power-dividing ratios. Hence, it can be expected that the proposed unequal power dividers will inspire further researches on SSPPs for future design of novel planar passive and active microwave components, circuits and systems.

Two important classes of passive superconductive microwave devices are described. These devices have been demonstrated using thin films of the high-temperature superconductor YBa/sub 2/Cu/sub 3/O/sub 7-x/. The devices include tapped-delay-line transversal filters with multigigahertz bandwidths and time-bandwidth products as large as 30, and narrowband (less than 3% bandwidth) microstrip filters. These devices illustrate the potential performance advantages superconductive thin films offer to the designer of a high-frequency, wide-bandwidth analog signal processing system. >

A circular patch antenna fed by an aperture coupled microstrip line has been demonstrated. The patch was enclosed by a cavity to reduce the surface wave interactions in an array environment and to improve heat dissipation when using active devices. A pedestal design was also implemented to help heat dissipation when using active microwave circuits. The antenna exhibited a 9.3% bandwidth from 9.55 to 10.48 GHz. >

This chapter contains sections titled: Terminations Attenuators Phase Shifters Directional Couplers Hybrid Junctions Power Dividers Microwave Propagation in Ferrites Faraday Rotation Microwave Devices Employing Faraday Rotation Circulators Other Ferrite Devices This chapter contains sections titled: Problems References

[EN] The general goal of this thesis is the development of a basic tool for the analysis of passive microwave and millimetre-wave devices used in the new generation of communication systems. In particular, the work is focused on the development of a tool for an efficient and accurate modal characterization of passive devices composed of waveguides with arbitrary cross section.
\nIn order to achieve this goal, a method recently arisen and called BI-RME (Boundary Integral - Resonant Mode Expansion) is extended. This method has been revealed as one of the most appropriate, for its high computational efficiency, to characterize waveguides with arbitrary cross section. Regarding the original BI-RME method, this one will improve the precision and the efficiency of the modal solution in presence of circular and elliptic perturbations in the arbitrary waveguide contour.
\nThen, the first work consists on extending the original BI-RME method theory to circular and elliptic geometries including the possibility to connect these two new types of segments (circular and elliptic) with the straight segments used until now in the practical implementation of the method.
\nIn order to validate the new developed theory, a set of parameters as the cut-off frequencies, the cut-off wavelengths or the electromagnetic fields of canonical waveguides and arbitrarily shaped waveguides of great practical interest, are calculated. These results are compared with analytical well-known solutions or results published in the literature.
\nOnce the electromagnetic modal chart of different arbitrarily shaped waveguides is obtained, the following step is the computation of the coupling integrals between these modes and the ones of the rectangular waveguide that completely surrounds the arbitrary contour. Such integrals are essential for the modal analysis of microwave passive structures involving waveguides with arbitrary cross section.
\nFor this purpose, the new extended BI-RME method is included into a software package tool based on the integral equation method, which allows to characterize efficiently waveguide discontinuities by means of inmitance matrices (admittance or impedance). This efficient full-wave analysis method requires the knowledge of the modal chart related to all the waveguides included in the devices under consideration, as well as the coupling integrals between the modes of the two waveguides composing the discontinuity. In the rectangular waveguides case this modal information can be easily obtained in an analytical way. However, when a waveguide or both have arbitrary cross section, the accurate and efficient modal analysis can be obtained by means of the BI-RME method.
\nThe use of the integral equation method based on admittance or impedance matrices to characterize devices composed of cascading waveguides is specially advantageous because it leads to a linear system of equations. The coefficients matrix of this linear system presents a banded structure that can be appropriately exploited to increase the computational efficiency associated to the resolution of the aforementioned system, and to reduce considerably the computational cost associated to the analysis of complex devices.
\nNext step is the demonstration that in waveguides with arbitrary cross section and with one or two symmetry axes you can generate, also by means of the BI-RME method, the whole family of waveguide modes, so that they verify a certain fictitious boundary condition of electric or magnetic walls in the symmetry plane, and the advantages regarding the computation of the modes are discussed. Furthermore, those different symmetry families of waveguide modes propagate in an independent way along the structures constituted by a connection of uniform waveguides. This situation can also be exploited to increase in a remarkable way the efficiency of the Computer-Aided-Design (CAD) electromagnetic software packages.
\nOnce verified with success the efficiency and precision of the new CAD tool developed by means of the analysis of transitions published in the related technical bibliography, the analysis of really complex passive waveguide devices is performed. Some passive waveguide devices analyzed are for instance a filter with inductive coupling windows and tuning screws, a filter with rounded corners, dual mode filters in circular waveguide with elliptic irises or in elliptic waveguides, an evanescent filter, a low bandpass filter in coaxial waveguide, and finally a new 90º twist component for space applications. The simulated results are totally validated by means of comparison with other data published in the related technical bibliography, or by means of measurements of manufactured prototypes.
\nFinally, the conclusions of this work are extracted and future research lines are outlined. Publications in journal and congress presentations in the framework of this thesis are also indicated.

Passive microwave devices

Epitaxial TI-Ba-Ca-Cu-O films—preparation, properties and applications

A high-temperature measurement system capable of performing on-wafer microwave testing of semiconductor devices has been developed. This high temperature probe station can characterize active and passive devices and circuits at temperatures ranging from room temperature to above 5OO°C. The heating system uses a ceramic heater mounted on an insulating block of NASA shuttle tile material. The temperature is adjusted by a simple graphical computer interface and is automatically controlled by the sohare-based feedback loop. The system is used with a Hewlett-Packard 8510C Network Analyzer to measure scattering parameters over a frequency range of 1 to 50 GHz. The microwave probes, cables, and inspection microscope are all shielded to protect from heat damage. The high temperature probe station has been successfully used to characterize gold transmission lines on silicon carbide at temperatures up to 540°C.

A full and rigorous treatment of conditional and unconditional stability and instability for an active 3-port microwave circuit, represented at a given frequency by S-parameters, is carried out. By terminating a given port with a variable termination one may study at the input and the output of the resulting 2-port circuit the occurrence of unconditional stability and instability, as well as of special cases of conditional stability, defined as reactive unconditional stability or instability. Such conditions are especially relevant in microwave oscillator design and were exhaustively identified for the first time and treated in previous analysis by the authors. Drawing from its conclusions, one obtains in the plane of the variable termination and with a simple algorithm, a single parametric representation, providing at once, in a closed and direct form, the entire collection of boundaries of the regions, wherein the listed conditions occur at ports of the resulting 2-port circuit. Guidelines for the design of microwave amplifiers and oscillators, both in series and shunt configuration, are sketched. Numerical examples, validated by simulations, are also presented.

Fully integrated microwave IC's have been in development since the 1970s. The move in recent years to complex microwave and millimeter-wave CMOS subsystems has prompted a considerable activity which must proceed in light of past developments and discoveries. This paper offers a perspective on pre-CMOS experience with active microwave circuits on a chip, some of which operated at 60 GHz. While a market for millimeter-wave consumer devices has yet to mature, there is enough research at hand to show that millimeter-wave electronics are feasible in the 60 to 77 GHz in state-of-the-art CMOS technology. It seems likely-or at least so the thinking goes-that the very existence of functional CMOS electronics, even antennas, which can be integrated with digital signal processing should pry open applications that lay dormant because of high cost. But millimeter-wave CMOS is not a straightforward extrapolation of RF-CMOS circuit design; it is a different circuit approach altogether, with roots that run much deeper than RF-CMOS. It is my purpose here to bring to light some of this history.

5 - Passive silicon photonic devices