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This brief introduces new methodologies to design microstrip line crossovers on a high-speed interconnection circuit. The crossover is based on a simple square patch, which employs TM100 and TM001 to achieve mode orthogonality so that two sets of intersecting signals can transmit along microstrip lines with a high isolation. Compared with rectangular waveguide crossovers that employ high modes, namely TE102 and TE201, it shows advantages like a smaller size and easier manufacturing. Then, the relevant techniques for performance improvement, including radiation suppression and bandwidth widening, are studied for practical circuit designs. Finally, based on the sub-element technique, the study designs a controllable frequency response for two intersecting signals and miniaturization of patch based crossovers. Two examples are implemented, manufactured and measured to justify the validity of the sub-element technology. In addition, the design steps of this method are simplified compared with relying on full-wave simulations entirely. [ABSTRACT FROM AUTHOR]

In this brief, substrate integrated waveguide (SIW) multi-channel filtering crossovers are proposed for two sets of intersecting signals operating at the same or different frequencies. The number of filtering channels in two directions can be independently extended. Square SIW cavities with TE102 and TE201 modes are used as building blocks. By properly arranging feeding ports and coupling regions, isolation between different channels is achieved and bandpass responses are integrated. The design procedure can be simplified as that of single-channel bandpass filter. For demonstration, a six- and a five-channel filtering crossovers with the same operating frequency in two directions are designed and fabricated. By etching a slot on the square SIW cavity, the TE102 and TE201 modes are split and thus the frequencies can be controlled. A four-channel filtering crossover with different operating frequencies in two directions is implemented for further verification. Compared to other multi-channel crossovers, the proposed designs feature good inter-channel isolation and intra-channel filtering responses with flexibly extended channel number and controllable frequencies. [ABSTRACT FROM AUTHOR]

A new type of compact filtering rat‐race couplers with arbitrary port direction based on different shape substrate integrated waveguide (SIW) cavity are first proposed in this paper. Different shaped SIW resonators can be combined together to achieve better performance and flexible topology. Resonant frequencies of fan‐shaped SIW cavity with various central angles have been derived to construct the resonant cells and obtain different topological structures. Moreover, interdigital capacitor SIW unit loaded on the common wall between cavities is used to achieve negative coupling structure. The detailed analysis and the design method have been introduced to realize a filtering rat‐race coupler based on substrate integrated fan‐shaped cavity (SIFC) and rectangular cavity. In particular, the combination of different shaped resonators can be selected according to the requirement of port angle interval. In order to further verify the method, the other filtering rat‐race coupler is fabricated using four SIFCs to achieve more available port angle intervals. Compared with other filtering couplers, the proposed designs exhibit good filtering responses, high Q factor, amplitude balance, as well as 0° and 180° phase differences. Furthermore, various angular intervals for input/output ports are convenience to meet the requirement of system topology and interconnect. [ABSTRACT FROM AUTHOR]

A compact filtering switch with wide-stopband responses is presented in this paper. The resonator is designed using microstrip transmission lines and lumped capacitors. It is utilized to shift up the second harmonic frequency for wide-stopband performance and miniaturize the circuit size. In the ON-state, the circuit is the same as the bandpass filter without signals passing through the p-i-n diode, which avoids additional loss introduced by p-i-n diode. Two transmission zeros are generated near the passband to enhance the skirt selectivity. In the off-state, the signals from port 1 to port 2 passing through different transmission path are cancelled out, resulting in high isolation. For demonstration, a filtering switch operating at 780 MHz is implemented with the compact size of 0.072λg×0.066λg. More than 20-dB suppression levels are measured from 0.89 to 5.3 GHz (6.8 f0), featuring wide-stopband responses.

In this paper, a method for designing substrate integrated waveguide (SIW) filtering rat-race couplers based on TE102 and TE201 orthogonal degenerate modes is proposed for the first time. Without additional circuits, the desired 0° and 180° phase differences of the rat-race coupler are realized by the inherent in-phase and out-of-phase characteristics of E-fields at TE102 and TE201 modes. E-field distributions of the SIW cavities at TE102 and TE201 modes are studied for guiding the circuit realization. By properly arranging the locations of input–output ports and coupling regions in the SIW cavities, magnitude and phase properties of the rat-race coupler topology are realized. And then the filtering responses can be integrated with the rat-race coupler. A detailed design method based on coupling matrix is presented. A filtering rat-race coupler is implemented using square SIW cavities to verify the proposed method, showing good performance of filtering responses, amplitude balance, as well as 0° and 180° phase differences. For further verification, another filtering rat-race coupler is fabricated using two circular SIW cavities to simplify the structure. Comparison with other filtering couplers indicates that the proposed designs exhibit the advantages of good filtering responses, relatively high Q factor of the entire filtering circuits, and simple structure. [ABSTRACT FROM AUTHOR]

In this paper, we propose a method for designing the narrowband filtering rat-race couplers using the quad-mode dielectric resonator (DR) for the first time. The filtering rat-race couplers are designed in single-cavity configuration with one quad-mode DR and four feeding probes, featuring compact size. Based on the investigation on resonant frequencies of a rectangular DR, a quad-mode DR is first constructed. Electromagnetic (EM) field distributions at two resonant mode pairs are studied for guiding the filtering rat-race DR coupler realization. The desired 0° and 180° phase differences of the rat-race coupler are realized by the inherent in-phase and out-of-phase EM-fields of the DR. By properly arranging the four feeding probes, the single-cavity configuration is designed to fulfill the transmission characteristics of a rat-race coupler topology, such as the magnitude and phase properties. The detailed design method is presented. For demonstration, a filtering rat-race coupler based on the rectangular DR is fabricated and measured, showing excellent performance of filtering responses, amplitude balance, as well as the 0° and 180° phase differences. Moreover, the other filtering rat-race coupler is implemented by using a cylindrical DR with an improved $Q$ -factor. Comparison with other reported filtering couplers indicates that proposed designs exhibit the advantages of compact size, high $Q$ -factor, and good filtering responses. [ABSTRACT FROM AUTHOR]

In this paper, a novel method for designing highpower filtering switches using dielectric resonators (DRs) is presented for the first time. The filtering switches consist of DRs and printed circuit boards. The latter are embedded in the metal cavity to enable the integration of p-i-n diodes. The ON- and OFF-states are realized by controlling the p-i-n diodes which are put in the feeding lines or nonresonance nodes (NRNs). Electromagnetic field properties of the DR (at TE11δ mode) and feeding line (or NRN) are studied and the coupling between them is investigated for guiding coupling control. In the ON-state, the filtering switches are equivalent to bandpass filters with no signal passing through the p-i-n diodes, which avoids additional loss introduced by p-i-n diodes and attains high power handling capability. In the OFF-state, the proposed filtering switches offer enhanced isolations by controlling the coupling of the filtering circuits, which differs from the conventional switches by turning off transistors or diodes. For demonstration, a DR-based filtering single-pole single-throw switch and a filtering single-pole doublethrow switch are implemented. High selectivity, low ON-state loss and high OFF-state isolation are observed. The measured P1dB is larger than 80 W, featuring high power handling capability. [ABSTRACT FROM AUTHOR]

This paper presents a compact power divider with wide-stopband bandpass responses. In the proposed circuit, two identical quarter-wavelength resonators are symmetrically coupled to a stub-loaded resonator to enable dual functions. Discriminating coupling is employed to suppress the third harmonic. By introducing series-connected two capacitors and one resistor, the isolation is enhanced to more than 20 dB. For demonstration, a filtering power divider operating at 2.4 GHz is designed and fabricated. Good agreement is observed between the measured and simulated results. [ABSTRACT FROM AUTHOR]

This paper presents a novel method for designing Gysel power dividers with arbitrary power-division ratios as well as filtering responses. A coupling structure is utilized to replace the quarter-wavelength microstrip line in the power divider. By altering the coupling strength, the power ratio can be arbitrarily controlled with the highest ratio of 10:1. Furthermore, the coupling structures enable the filtering function of the power divider. Two transmission zeros are created near the passband edges, resulting in high-selectivity quasi-elliptic responses. Theoretical analysis is carried out, and closed-form equations are derived based on circuit theory and transmission line theory. For demonstration, three filtering Gysel power dividers are implemented with different power-division ratios (1:1, 3:1, and 10:1). In all of these circuits, power splitting and bandpass filtering functions are observed with good performance. Comparisons of the measured and simulated results are presented to verify the theoretical predications. [ABSTRACT FROM AUTHOR]