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The development of millimeter-wave and terahertz (THz) passive components such as couplers and filters is an intimidating task because of underlying ultrasensitivity of electrical performances to geometric dimensions and processing tolerances. It is a common practice for us to use an integrated optimizer of commercial electromagnetic (EM) software packages for the design and optimization of such geometric parameters. However, those optimizers may fail to achieve a desired performance if initial variables are not in a range close enough to the optimal solution. In this article, we introduce an homotopy approach to optimizing the geometric parameters of a $D$ -band cruciform coupler based on substrate integrated waveguide (SIW) technique in conjunction with an artificial neural network (ANN) model. Starting from a set of initial variables, a homotopy optimization is set to search for an optimum solution. The ANN technique is adopted as the surrogate in place of a usual time-consuming EM model to accelerate the homotopy optimization process of the cruciform coupler. We propose a feed-forward computational formulation inspired by the fundamental transmission line impedance equation. Such a transmission line knowledge-based feedforward network results in a faster convergence with better accuracy than its conventional counterpart. To demonstrate the homotopy optimization method based on the ANN model, an example of multiparameterized cruciform coupler design is detailed. This cruciform coupler with optimized geometric dimensions is simulated, fabricated, and measured. Measured and simulated results validate the combined ANN model and homotopy method. An equivalent lumped-element circuit model of the cruciform coupler is also proposed in this work. An ANN model development technique is described how to extract the equivalent circuit parameters for given coupler specifications. Extracted circuit parameters in connection with the desired coupler performance are then compared with published results which verify the ANN model development algorithm. [ABSTRACT FROM AUTHOR]

This article presents the generation scheme of picosecond (ps) pulses based on both step recovery diode (SRD) topology and nonlinear transmission line (NLTL) scheme with a focus on simultaneous rise and fall time compression. First, the SRD topology is suggested and investigated for manifesting the capability of pulse compression. The SRD solution is then integrated with different NLTL schemes for alienating and achieving rise or fall time compression in the ps regime. It is observed that single NLTL integration only sharpens the rising or falling edge at the same time. To overcome this challenge, two NLTLs having different diode polarities are then integrated with SRD topology-based ps pulse generator to compress rise and fall time simultaneously. The theory of NLTL is developed in each case, and based on it, the shortest rise and fall time is selected for the final design. Several parameters that are responsible for waveform distortion are also investigated in detail as well. Finally, we have fabricated four different pulse generators in which the first three only compress the rise time whereas the fourth one is responsible for both rise and fall time compressions. The overall pulse duration for the first three generators falls within 80–95 ps having different ringing levels and they are based on rise time compression only. The pulse duration for the fourth pulse generator is almost 25 ps having a detailed ringing level of −14.24 dB and full-width at half-maximum (FWHM) of 10.1 ps based on both rise and fall time compressions. Finally, all these pulse generators are compared with the state of the arts in the literature where they utilize different techniques for sharpening and the superiority of our proposed designs is provided. These generators will find their key role and will be the best candidates for ultra-wide band (UWB) radars for electromagnetic imaging and sensing applications, ultrafast electronic techniques including edge sharpening, future oscilloscopes, comb, or pulse generators, and geophysical exploration. [ABSTRACT FROM AUTHOR]

Radiation efficiency of electrically small antennas largely depends on antenna geometry. However, the actual mechanism that governs the antenna radiation efficiency remains unclear, although various models have been developed since the 1940s. Extant circuit models are either intuition-based or mathematic representations of input impedance/far-field spherical mode functions for structurally simple antennas with limited uses and physical insight. In this article, a recently developed physical micromodeling circuit (MMC) model is utilized to explain the nature of radiation of an electrically small antenna of arbitrary configuration. It is theoretically discovered and experimentally validated for the first time that the radiation efficiency decisively depends on mutual radiated power associated with partial segments of the antenna. A circuital figure of merit for describing the total mutual radiated power is introduced to quantify the measure. The graphical representation of the figure of merit called the holographic radiation diagram is also proposed for illustrating the correspondence of the positive and negative radiated power and the antenna structure. The applications of the proposed theory to antenna design is demonstrated by designing a highly efficient loop antenna. The physical circuit model paves a new way of understanding electromagnetic (EM) radiation problems. [ABSTRACT FROM AUTHOR]

A generalized mesh-network equivalent model for a microstrip rectangular patch antenna (RPA), which is simple yet efficient is proposed, studied, and demonstrated in this article. The mesh-network equivalent model is established through the segmentation of RPA width and radiation parameters into $M$ sections, as well as the segmentation of RPA length into $N$ sections. A general design procedure to realize the mesh-network equivalent model is addressed and described for any number of RPA segmentations, as desired by specific applications. Subsequently, the proposed mesh-network equivalent model is used to accurately evaluate the input impedance responses at various feed positions along the length of RPA. In addition, to include the effects of a slot etched inside the RPA geometry, a generalized microstrip coupled line equivalent model is proposed, analyzed, and discussed in detail. Eventually, the microstrip coupled line model in conjunction with the proposed mesh-network equivalent model can accurately estimate the input impedance response of a slotted RPA, and has been verified for RPA with center slot, edge slot, and multiple slots as examples in this work. Two cases with multiport excitation of RPA are also analyzed and presented as a part of this work. For demonstration purposes, all these prototypes are designed, fabricated, and measured at 28 GHz. The proposed equivalent model-based results are validated by measured and simulated counterparts. Furthermore, the extension of the proposed mesh-network model to accommodate slots of smaller size inside RPA, RPA loaded with via, inverted-F antenna, and multimode operation are demonstrated and discussed through a comparison between mesh-network modeling results and simulation results. [ABSTRACT FROM AUTHOR]

The concept of a self-decoupled antenna array using the cancellation of two opposite couplings is proposed in this article. A pair of such antennas can be closely placed with inherent high isolation without using an extra decoupling structure between the antennas. A pertinent equivalent circuit model is presented to illustrate the physical mechanism of this new concept. It is found that the inductive and capacitive couplings between the antennas can be well canceled out with each other by properly adjusting the antenna dimensions. A demonstrating antenna array with a spacing of $0.024\lambda _{0}$ at the working frequency of 3.5 GHz and its counterpart array are first studied. The measured results show that although the proposed antenna array occupies a slightly larger size than its counterpart array, it presents better performance compared with its counterpart antenna array in port isolation (from 10 to 20 dB), total efficiency (from 68% to 80%), and envelope correlation coefficient (ECC) (from 0.14 to 0.04) throughout the desired frequency band of 3.3–3.8 GHz. A 3-D self-decoupled antenna array is designed to show that the proposed antenna can be in a compact form factor. Another self-decoupled array and its counterpart working at 2.14 GHz (long-term evolution (LTE) band 1) are studied through multi-input multi-output (MIMO) over-the-air (OTA) test when the arrays are integrated with an LTE module, showing significant improvement on the data throughput. [ABSTRACT FROM AUTHOR]

In this article, a passive full-wave partial element equivalent circuit (PEEC) model is formulated for modeling electromagnetic (EM) problems with finite dielectrics. The proposed PEEC model is a substantial extension of the generalized PEEC model for problems of multiple conductors in free space. The proposed generalized PEEC model reflects the physical radiation mechanism of an EM problem with finite dielectrics. The radiation effects, both from conductors and dielectrics, are incorporated in real-valued frequency-dependent inductances and resistances, while capacitances remain to be frequency invariant. Consequently, the resultant circuit model of the proposed PEEC model is numerically verified to be more passive than the existing PEEC models. The minor passivity violation can be amended without altering the circuit configuration. To model a dielectric with the irregular-shaped surface, a triangular meshing scheme with Rao–Wilton–Glisson (RWG) basis is used. The generalized PEEC model provides a passive circuit model for both the frequency- and time-domain modeling of an EM problem with finite dielectrics. The passivity and accuracy of the generalized PEEC model are validated by an low temperature co-fired ceramic (LTCC) multilayer filter module, two dielectric resonator antennas, and a patch antenna. [ABSTRACT FROM AUTHOR]

In this article, an efficient transient analysis method for high-speed interconnection and packaging problems is proposed. The method is committed to a full-wave generalized partial element equivalent circuit (G-PEEC) model with guaranteed stability and causality. With the proposed method, the full-wave G-PEEC model is represented by a few static compact subcircuits that are derived by applying the micromodeling circuit method to the G-PEEC model at a few discrete frequency points. Its transient response can be obtained by a linear combination of responses of the compact subcircuits, which can be simulated by the transient analysis method of SPICE. By adopting the compact subcircuits, which is an order reduced G-PEEC model, the transient simulation can be speeded up by two orders of magnitude when compared with the case if the subcircuits are generated directly from the G-PEEC model. Since the compact subcircuits are static, physically meaningful, and passive, the proposed transient analysis is with guaranteed stability and causality. Moreover, a frequency compensation strategy is proposed for preparing input signals of subcircuits to avoid the Gibbs phenomenon. Finally, three numerical examples, including eye-diagrams for a practical multilayer interconnection problem, are given, demonstrating the effectiveness, accuracy, scalability, and simplicity of the proposed method. [ABSTRACT FROM AUTHOR]

A passive full-wave micromodeling circuit (FW-MMC) is proposed for high-speed/frequency interconnection problems. The circuit is derived from an FW generalized partial element equivalent circuit (G-PEEC) model, in which the radiation effect and other FW phenomena are fully taken into account. The proposed concise physically sensible circuit is obtained by recursively using a physics-based equivalent circuit transformation for absorbing the insignificant nodes of the G-PEEC model. To ensure the fidelity of the physical nature and the passivity of the MMC, the necessary broad sense criterion and the sufficient narrow sense criterion are systematically derived. It has been shown through numerical examples that the passivity violation of the physically sensible circuit model is very weak and can be effectively mediated. Thanks to the one order of magnitude reduction in the model order, the simulations for frequency- and time-domain system responses using the proposed MMC are three and two orders of magnitude faster, respectively, as compared with the G-PEEC model. Two practical examples for both frequency- and time- domains are given to demonstrate the high fidelity, scalability, accuracy, passivity, and efficiency of the FW-MMC. [ABSTRACT FROM AUTHOR]

Frequency-dependent coupling (FDC) emerges as a new method to introduce the finite-position transmission zeros (TZs) in the synthesis and design of filtering networks. In this paper, several fundamental building blocks with FDCs are introduced and studied. The higher order filters with many TZs can be constructed by cascading these fundamental building blocks. As compared with the conventional coupled-resonator filters with only constant couplings, the inclusion of FDCs can potentially create more TZs with the same coupling topology. It is also shown that to realize the same TZs, a filter can be realized in a simplified structure with less cross-couplings by using FDCs. In this paper, one complete filter design procedure is illustrated, including the steps of the circuit model synthesis by the method introduced in this paper, physical dimensioning of the filter by the electromagnetic simulation and measurement of the fabricated filter. The measurement results are in very good agreement with the theoretical predictions, which validates the modular design strategy for filters with FDCs. [ABSTRACT FROM AUTHOR]

A class of self-isolated harmonic oscillator (SIHO) with a feedback-loop structure is able to significantly reduce the pulling effect without involving extra circuit complexity such as a buffer amplifier. In the first part of this paper, the operation principle of the SIHO is theoretically studied through equivalent circuit models and X-parameter techniques. Closed-form expressions are derived to represent the respective linear and nonlinear equivalent impedances of SIHO subnetworks perturbed by varied load and injected signals. A conventional feedback-loop oscillator structure delivering the fundamental tone is used for comparative study. Such a modeling technique reveals the physical principle and behavior parameters that have an impact on the pulling effect. The experimental verification of the SIHO operation principle and modeling is presented as the second part of this paper. To this end, a harmonic measurement and design system is proposed and implemented for the design of an exemplary SIHO, which delivers a 4-GHz signal with 16.6-dBm power, 28% dc-RF efficiency, and −136.5-dBc/Hz phase noise at 1-MHz offset. The design process does not rely on circuit simulation software packages or a prior knowledge of the large-signal model of transistors, thus demonstrating the concept of a model-free nonlinear circuit design automation based on the experimental optimization. The SIHO circuit model is validated with the measured X-parameters of its nonlinear subnetwork. [ABSTRACT FROM AUTHOR]

This paper presents a quasi-static surface-based partial element equivalent circuit (PEEC) model for electromagnetic problems consisting of coupled conductors and heterogeneous dielectrics of finite size. The PEEC model is based on the surface equivalent principle. Unlike the traditional surface-based PEEC models, in which the integral equations are set up by enforcing the field continuity in the true field region, the homogeneous integral equations in this model are obtained by enforcing the tangential null field condition in the null field regions. Simplified integral equations are obtained under the quasi-static assumption, in which the circuit elements carrying electric currents and magnetic charges on the dielectric surfaces are vanished. Consequently, the size of the subcircuit describing dielectrics is reduced significantly compared to the full-wave surface-PEEC (S-PEEC) model. Since the quasi-static S-PEEC model only contains frequency-independent circuit elements, it can be conveniently used for time-domain simulation. Three numerical examples are presented to validate the new PEEC model for typical embedded RF passive components, packaging and interconnection problems in both the frequency domain and the time domain. Excellent agreement is observed between the results of the proposed PEEC model, S-PEEC model, and those of commercial software within the quasi-static frequency range. [ABSTRACT FROM AUTHOR]

A passive partial element equivalent circuit (PEEC)-based micromodeling circuit is proposed for time-domain simulation of a high-speed interconnection problem. This physics-based model order reduction method derives a concise and physically meaningful circuit model from the PEEC model by absorbing its insignificant nodes. To maintain high fidelity of the original electromagnetic PEEC model, the concept of pseudoinductor is introduced to the node-absorbing process. The derivation process does not involve any matrix inversion or decomposition and is highly suitable for GPU parallel computations. Passivity of the micromodeling circuit is ensured by a new passivity checking and enforcement method proposed for the first time. As the scale of the micromodeling circuit can be one order of magnitude smaller than that of the original PEEC model, the time-domain simulation can be three orders of magnitude faster. Two practical examples are given to demonstrate the high fidelity, scalability, and accuracy of the proposed micromodeling circuit, showing excellent applicability to high-speed interconnection problems. [ABSTRACT FROM PUBLISHER]

In this paper, an analytical coupling matrix extraction scheme is proposed for parallel-connected dual-passband coupled-resonator filters for the first time. Model-based vector fitting technique is adopted to fit the measured responses of the dual-passband filter (DPBF) with a set of rational functions, from which a transversal coupling matrix can be constructed. A novel coupling matrix transformation strategy is developed to transform the transversal coupling matrix to the one corresponding to the topology of a parallel-connected DPBF. A practical filter is used as a test example to demonstrate the extraction procedure. In diagnosing the coupling matrix of the test filter, two kinds of ambiguity problems are discussed in detail and are solved by a perturbation technique. This paper provides a general theoretic framework for computer-aided tuning of a parallel-connected dual-passband or multiple-passband filter. [ABSTRACT FROM PUBLISHER]

This paper is devoted to theoretical and practical issues concerning computer-aided tuning (CAT) of coupled-resonator diplexers with tapped wire T-junction. Special attentions are paid to the following aspects: 1) finding an appropriate circuit model to represent the tapped wire T-junction; 2) developing a legitimate transformation strategy to obtain the coupling matrix of the right form corresponding to the topology of the diplexer containing a tapped wire T-junction; and 3) proposing an adaptive CAT scheme that takes stray couplings into account in a dynamically optimized target coupling matrix. A conventional combline diplexer and a helical resonator diplexer are used as examples to demonstrate the circuit model extraction procedure and the adaptive CAT concept, showing the effectiveness and robustness of the proposed adaptive CAT method for practical applications. [ABSTRACT FROM PUBLISHER]

In this paper, a unified method is introduced and formulated for deriving the equivalent circuit model of a guided wave structure as well as its characteristic impedance for any mode. This method is developed through the combination of a generalized multimode calibration and a full-wave simulation, and it is applicable to the fundamental mode as well as higher order modes. The method is verified for both TEM and non-TEM propagating modes and is applied to extract the characteristic impedance and circuit model of non-TEM guided-wave structures. This scheme allows for the effective use of a commercial electromagnetic field simulator in removing inherent numerical simulation noises or errors. Extracting circuit parameters through this technique for establishing equivalent circuit models can overcome the shortcomings encountered in the modeling of guided-wave eigenvalue problems as well as in the design of multimode structures. [ABSTRACT FROM PUBLISHER]

In this paper, a new concept of matrix-inversion-less derived physically expressive circuit method of model order reduction for large-scale high-speed/microwave circuit problems is proposed. It is the first model that is derived based on the mesh information of partial element equivalent circuit modeling. This new proposed method absorbs insignificant nodes and parallel branches while retaining the physical meaning of all the inductive and capacitive elements. This method does not involve any matrix inversions or decompositions and its computational overhead is dominated by outer products that can be simply accelerated by the massive GPU acceleration technique. The resultant order-reduced circuit is very useful for not only speeding up the analysis of a large-scale high-speed/microwave circuit but also interpreting the physical insight of the circuit layout from the circuit domain point of view. Three numerical examples are given, demonstrating the versatility, scalability, accuracy, and simplicity of the method. [ABSTRACT FROM PUBLISHER]

In this paper, a novel rational function approximation method, namely, model-based vector fitting (MVF), is proposed for accurate extraction of the characteristic functions of a coupled-resonator diplexer with a resonant type of junction from noise-contaminated measurement data. MVF inherits all the merits of the vector-fitting (VF) method and can also stipulate the order of the numerator of the model. Thus, MVF is suitable for the high-order diplexer system identification problem against measurement noise. With the extracted characteristic functions, a three-port transversal coupling matrix of a diplexer can be synthesized. A matrix orthogonal transformation strategy is also proposed to transform the obtained transversal matrix to a target coupling matrix configuration, whose entries have one-to-one relationship with the physical tuning elements. The whole model extraction procedure is analytical and robust, and can be used in a computer-aided tuning (CAT) program for coupled-resonator diplexers. A practical tuning example of a diplexer with a common resonator is given in detail to demonstrate the effectiveness and the practical value of the proposed method. [ABSTRACT FROM AUTHOR]

This paper presents an iterative and analytical approach to optimal synthesis of a multiplexer with a star-junction. Two types of commonly used lumped-element junction models, namely, nonresonant node (NRN) type and resonant type, are considered and treated in a uniform way. A new circuit equivalence called phased-inverter to frequency-invariant reactance inverter transformation is introduced. It allows direct adoption of the optimal synthesis theory of a bandpass filter for synthesizing channel filters connected to a star-junction by converting the synthesized phase shift to the susceptance compensation at the junction. Since each channel filter is dealt with individually and alternately, when synthesizing a multiplexer with a high number of channels, good accuracy can still be maintained. Therefore, the approach can be used to synthesize a wide range of multiplexers. Illustrative examples of synthesizing a diplexer with a common resonant type of junction and a triplexer with an NRN type of junction are given to demonstrate the effectiveness of the proposed approach. A prototype of a coaxial resonator diplexer according to the synthesized circuit model is fabricated to validate the synthesized result. Excellent agreement is obtained. [ABSTRACT FROM AUTHOR]

Substrate integrated waveguide (SIW) cavity backed dual-band triangular-ring slot (TRS) antennas are proposed for planar integration. First, a low profile dual band 45^\circ linearly polarized (LP) antenna is designed and analyzed. The dual-mode TRS is proposed and developed by simultaneously exciting the mode of the slot and the mode of the patch inside the slot. To minimize the antenna size, the lowest mode (TE110 mode) of the SIW cavity is adopted to excite the TRS. The -10 dB impedance bandwidth at the higher band is 5.9%, 58.3% wider than that of the conventional SIW cavity backed slot antenna. The interactions of the SIW cavity, the slot mode and the patch mode are analyzed with circuit models and verified by full wave simulations, which provides a new insight into the SIW cavity backed antennas. Then, by exciting a pair of the 45^\circ LP antennas with an SIW coupler, a circularly polarized (CP) dual band antenna with a small frequency ratio of 1.26 is developed. The two antennas are fabricated and tested, and the measured and simulated results agree well. [ABSTRACT FROM PUBLISHER]

This paper proposes and presents a class of substrate integrated waveguide (SIW) power dividers/combiners based on a modified Wilkinson architecture. The proposed design consists of a ring-type circuit of \(1.5~\lambda _{g}\) length with three waveguide ports. Impedance variation without affecting cutoff frequency and integration of isolation resistance are the two major limitations in connection with the design of SIW Wilkinson structures. Central ring part with different thickness ensures different impedance in the first proposed scheme while the half-mode SIW in the second option. As for the second limitation, the optimal configuration of integrating the isolation resistance is studied. A version without resistance is also examined using a broad-wall series slot. To validate the proposed concept, a bilayered circuit with standard Printed circuit board prototype was fabricated and measured. A table summarizing performances of all the proposed circuits shows a bandwidth of around 25% at the 10 dB reference. A negligible additional insertion loss is observed. The proposed design techniques are found useful at millimeter-wave frequencies where reduced physical dimensions make a circuit configuration suitable for low-cost implementation. This concept is also valid for rectangular waveguide counterparts. [ABSTRACT FROM AUTHOR]

In this paper, a vector fitting (VF) based analytical extraction method, which is capable of accurately extracting the coupling matrix and the uneven unloaded Qs of each electric resonators of a filter, is presented. Having had the complex poles and residues determined using VF, the coupling matrix can be obtained by a sequence of complex orthogonal transformations. As a side product, the unloaded Qs for each resonator will be directly obtained from the complex diagonal elements of the coupling matrix. To demonstrate the effectiveness of the proposed method, an ideal demonstrative example along with two practical challenging filter tuning examples, namely, an eight-pole dual-mode dielectric filter and an eight-pole dual-mode predistortion filter, are demonstrated. An excellent match between the responses of the measured data and those from the extracted coupling matrix with actual unloaded Q factors can be seen. [ABSTRACT FROM AUTHOR]

Since S-parameters [1] were first used to describe linear microwave circuits in the 1960s, circuit designers, software developers, and instrument manufacturers have gradually come to an agreement on this blackbox representation, resulting in significant advancements in modeling, simulation, and measurement. As a mathematical language of high-frequency signal transmission and scattering, S-parameter stands for a unified form of the linear characteristics of microwave networks in the frequency domain. Subsequently, the vector network analyzer (VNA) was invented as the principal instrument to measure S-parameters and characterize the linear behavior of devices and components, including small-signal active circuits. [ABSTRACT FROM PUBLISHER]

Circular waveguide dual-mode (CWDM) filters have been widely employed in the manifold-coupled output multiplexer (OMUX) for satellite payloads. In this paper, a deterministic electromagnetic (EM) design technique for fast and accurately computerized prototyping a general CWDM filter is presented. By introducing a generalized K impedance inverter using the generalized scattering matrix of the tuning screw section, the insertion phase and the coupling of the two degenerate modes in a CWDM cavity can be determined by a most effective way. To handle the asynchronously tuned cases, the theoretical formula that relates a self-coupling to its corresponding phase offset is derived. The design technique is based on modal analysis at the center frequency and is deterministic without using optimization or curve fitting. The presented technique enables the full-wave EM design of CWDM filters as easy and accurate as designing conventional single mode waveguide filters. To validate the design technique, practical design of eight-pole symmetric and asymmetric CWDM filters have been studied theoretically and experimentally. An EM design of a complete Ku-band 15-channel contiguous OMUX is also demonstrated. [ABSTRACT FROM AUTHOR]

A stepped circular waveguide dual-mode (SCWDM) filter is fully investigated in this paper, from its basic characteristic to design formula. As compared to a conventional circular waveguide dual-mode (CWDM) filter, it provides more freedoms for shifting and suppressing the spurious modes in a wide frequency band. This useful attribute can be used for a broadband waveguide contiguous output multiplexer (OMUX) in satellite payloads. The scaling factor for relating coupling value M to its corresponding impedance inverter K in a stepped cavity is derived for full-wave EM design. To validate the design technique, four design examples are presented. One challenging example is a wideband 17-channel Ku-band contiguous multiplexer with two SCWDM channel filters. A triplexer hardware covering the same included bandwidth is also designed and measured. The measurement results show excellent agreement with those of the theoretical EM designs, justifying the effectiveness of full-wave EM modal analysis. Comparing to the best possible design of conventional CWDM filters, at least 30% more spurious-free range in both Ku-band and C-band can be achieved by using SCWDM filters. [ABSTRACT FROM AUTHOR]

This paper presents and demonstrates a class of 3-D integration platforms of substrate-integrated waveguide (SIW). The proposed right angle E-plane corner based on SIW technology enables the implementation of various 3-D architectures of planar circuits with the printed circuit board and other similar processes. This design scheme brings up attractive advantages in terms of cost, flexibility, and integration. Two circuit prototypes with both 0- and 45^\circ vertical rotated arms are demonstrated. The straight version of the prototypes shows 0.5 dB of insertion loss from 30 to 40 GHz, while the rotated version gives 0.7 dB over the same frequency range. With this H-to-E-plane interconnect, a T-junction is studied and designed. Simulated results show 20-dB return loss over 19.25% of bandwidth. Measured results suggest an excellent performance within the experimental frequency range of 32–37.4 GHz, with 10-dB return loss and less than \pm4^\circ phase imbalance. An optimized wideband magic-T structure is demonstrated and fabricated. Both simulated and measured results show a very promising performance with very good isolation and power equality. With two 45^\circ vertical rotated arm bends, two antennas are used to build up a dual polarization system. An isolation of 20 dB is shown over 32–40 GHz and the radiation patterns of the antenna are also given. [ABSTRACT FROM PUBLISHER]

A novel planar broadband microstrip-to-waveguide transition is proposed in this paper. The referred waveguide can be either rectangular waveguide or ridged waveguide. The transition consists of an open-circuited microstrip quarter-wavelength resonator and a resonant U-shaped slot on the upper broadside wall of a short-circuited waveguide. A physics-based equivalent-circuit model is also developed for interpreting the working mechanism and providing a coarse model for engineering design. The broadband transition can be regarded as a stacked two-pole resonator filter. Each coupling circuit can be approximately designed separately using the group-delay information at the center frequency. In addition to its broadband attribute, the transition is compact in size, vialess, and is highly compatible with planar circuits. These good features make the new transition very attractive for the system architecture where waveguide devices need to be surface mounted on a multilayered planer circuit. Two design examples are given to demonstrate the usefulness of the transition: one is a broadband ridged-waveguide bandpass filter and the other is a surface-mountable broadband low-temperature co-fired ceramic laminated waveguide cavity filter. Both filters are with the proposed transition for interfacing with microstrip lines, showing promising potentials in practical applications. [ABSTRACT FROM PUBLISHER]

A novel, broadband, vialess, and vertical microstrip-to-microstrip transition is proposed in this paper. The transition consists of two open-circuited microstrip resonators and a U-shaped resonant-slot on the common ground plane. A physics-based equivalent-circuit model is developed for interpreting its working mechanism and facilitating the design process. The transition is analogous to a three-pole resonator filter. Based on the equivalent-circuit model, the coupling coefficients of the physical circuit can be calculated from the group delay information of two segregated electromagnetic models. To effectively control the couplings, a modified configuration is also proposed. A prototype transition is designed using the proposed design formulas. The fabricated circuit is measured to validate the proposed transition and the equivalent-circuit model. Good agreement is obtained between not only the measured and the simulated performance, but also the designed and the extracted-circuit model. In addition to the wide bandwidth, the features of vialess and easy fabrication make the novel transition very attractive for system-on-package applications. [ABSTRACT FROM PUBLISHER]

In this paper, a new frequency-domain formulation of the partial element equivalent circuit (PEEC) model incorporating the concept of generalized complex partial inductance and pure real capacitance is introduced for modeling of 3-D structures, to which the radiation effect is not negligible. Unlike conventional PEEC-based models, the proposed formulation accounts for the radiation effect by introducing physically meaningful complex-valued inductors and pure real-valued capacitors. In essence, the imaginary part of such an inductor represents a frequency-dependent radiation resistance. Having introduced the complex inductance, there is no inversion of the complex matrix of coefficients of potential, which is not physically meaningful and inevitably creates negative resistance. It is proven in this paper that the imaginary part of the generalized complex inductance for a short dipole exactly reflects the radiation resistance of the dipole. Several numerical examples are given to validate the proposed theory. The results obtained are in good agreement with those from commercial full-wave EM solvers, showing the potential of this technique for analyzing and designing high-frequency and high-speed electronic devices. [ABSTRACT FROM AUTHOR]

In this paper, a planar 180^\circ phase-reversal T-junction and a modified magic-T using substrate integrated waveguide (SIW) and slotline are proposed and developed for RF/microwave applications on the basis of the substrate integrated circuits concept. In this case, slotline is used to generate the odd-symmetric field pattern of the SIW in the phase-reverse T-junction. Measured results indicate that 0.3-dB amplitude imbalance and 3^\circ phase imbalance can be achieved for the proposed 180^\circ phase-reversal T-junction over the entire X-band. The modified narrowband and optimized wideband magic-T are developed and fabricated, respectively. Measured results of all those circuits agree well with their simulated ones. Finally, as an application demonstration of our proposed magic-T, a singly balanced mixer based on this structure is designed and measured with good performances. [ABSTRACT FROM AUTHOR]

A novel wide stopband bandpass filter implemented with spur stepped impedance resonator (SSIR) and substrate integrated coaxial line (SICL) technology is proposed in this letter. SSIR possesses capabilities of both suppressing and staggering spurs without complicated fine-tuning, and SICL is very suitable for wide stopband applications. A prototype with compact size is fabricated, and the measured results exhibit extended stopband up to 8.76 f0 with a rejection better than 40 dB (except for a little 36.5 dB burr in 7.06 f0), or 9.36 f0 with rejection better than 30 dB. [ABSTRACT FROM PUBLISHER]

In this letter, a novel compact and broadband integrated transition between a laminated waveguide and an air-filled rectangular waveguide operating in Ka band is proposed. A three-pole filter equivalent circuit model is employed to interpret the working mechanism and to predict the performance of the transition. A back-to-back prototype of the proposed transition is designed and fabricated for proving the concept. Good agreement of the measured and simulated results is obtained. The measured result shows that the insertion loss of better than 0.26 dB from 34.8 to 37.8 GHz can be achieved. [ABSTRACT FROM PUBLISHER]

A letter to the editor is presented in response to the article "A Parameter-Extraction Method for Microwave Transversal Resonator Array Bandpass Filters with Direct Source-Load Coupling" by M. Ohira and Z. Ma in the May 2013 issue.