Microwave Circuits

Differential Filter Design and Optimization

In this application note, analysis and optimization of a differential microwave circuit using WIPL-D Microwave Pro is presented. Differential/common-mode analysis is performed by connecting transformer elements to convert single-mode S-parameters to differential/common-mode S-parameters. Differential filter illustrates the procedure, analyzed as an ideal transmission line, a microstrip schematic, and a 3D EM component. Converting the ideal circuit to a realistic microstrip introduces parasitic effects, fully considered during EM optimization. This method applies to other differential components such as amplifiers, couplers, and antenna matching networks, enabling accurate simulation and efficient optimization of complex microwave circuits.

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Rectangular Waveguide
Iris-Coupled Filter

This application note describes the detailed simulation of a band-pass interdigital filter in rectangular waveguide technology, modeled in WIPL-D Pro CAD using the native editor and built-in primitives. A symmetry plane was carefully utilized to reduce structural complexity, and two waveguide ports served as feeders. The model was simulated from 5 GHz to 14 GHz at 26 frequency points, with convergence checks performed to ensure high accuracy. After the convergence study, filter dimensions were finely tuned to achieve S11 values below –20 dB in the passband (8.30–10.86 GHz). Simulations can be efficiently performed on any desktop or laptop, preferably with multiple CPU cores, with per-frequency simulation times measured in seconds overall efficiency.

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Effective Antenna Design by
EM-Circuit Co-Simulation

Circuit–EM co-simulation reduces complexity by dividing a system into parts requiring full-wave electromagnetic analysis and parts handled with predefined circuit models, enabling efficient evaluation of large structures. In this case, two microstrip patch antennas are combined with a detailed feeding network consisting of microstrip lines, a T-junction, and several bends, forming a compact system analyzed from 9 to 11 GHz in nine evenly spaced points around a 10 GHz center. Through tight coupling between WIPL-D’s EM and circuit solvers, the overall problem is decomposed into smaller electromagnetic tasks, significantly cutting the number of unknowns and ensuring that simulation runtimes remain short on standard desktop computer.

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Bond Wires as Interconnect Technology

In this application note, accurate modeling of bonding wires is vital for effective use of semiconductor bare dies and achieving high integration in modern microwave front ends.
WIPL-D Microwave Pro offers a unified, versatile environment where EM and circuit simulations efficiently reveal how interconnects impact overall system performance in realistic scenarios. The narrow return-loss bandwidth of single wire bonds is shown through amplifier degradation, while double bonds demonstrate clear, measurable improvement and the reasons behind it. Examples focus on designs near 24 GHz, where interconnect effects intensify and practical compensation techniques or alternative technologies like flip-chip or µBGA must be considered carefully.

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Dielectric Resonator Filter [Verified by Measurements]

This application note presents the simulation of complex dielectric resonator filters with multiple tuning elements using WIPL-D software. Starting from a single cavity with a coaxial loop, a solid cubic dielectric puck is inserted to modify resonance, followed by a hollow puck for further tuning. WIPL-D Sweeper demonstrates resonance shifts by changing puck length. The single-cavity model, tuned for wide and deep resonance matching measured results, runs in seconds per frequency point using only 11 points thanks to built-in interpolation. Finally, mirrored cavity connected via goal-post configuration is simulated efficiently on a standard desktop or laptop, maintaining fast, accurate, and reliable results across the frequency band.

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3-Port Wilkinson at High Microwave Frequencies

In this note, accurate modeling of high-frequency effects for a Wilkinson power combiner/divider is demonstrated using WIPL-D Microwave, providing a complete circuit and EM co-simulation environment. The design cycle starts with an ideal schematic, progresses to a detailed schematic including microstrip discontinuity models, and then incorporates a full EM component for precise microstrip circuit modeling. Finally, the impact of a real-world resistor is analyzed. Each step’s effect on performance degradation compared to the ideal circuit is illustrated, giving designers clear guidance on mitigating issues early, such as selecting the smallest resistor size and optimizing substrate and line-to-pad length ratios for improved performance.

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Cavity Filter Design and Optimization

This application note demonstrates extremely efficient interoperability of WIPL-D software: WIPL-D Pro CAD, WIPL-D Microwave Pro, WIPL-D Pro, and WIPL-D Optimizer—for design, modeling, simulation, and optimization of cavity filters. A complex 2.1 GHz five-cavity pass-band filter is imported, meshed, and simulated in WIPL-D Pro CAD and WIPL-D Pro, then optimized in WIPL-D Microwave Pro with WIPL-D Optimizer. EM simulation is done once, while optimization uses a combined 3D/circuit model, where tuning capacitors emulate screw adjustments, enabling fast, precise tuning. WIPL-D supports simplified geometries in WIPL-D Pro or detailed CAD-imported models in WIPL-D Pro CAD, offering flexibility, accuracy, and speed for advanced filter design.

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Designing a Band Pass Filter with WIPL-D Filter Designer

This application note describes design of a microstrip filter, emphasizing an efficient optimization technique based on a simplified Space Mapping method. The process results in a filter ready for prototype fabrication with minimal manual and numerical effort. Design success is maximized by considering standard fabrication limitations, including substrate selection and dimensional constraints. All simulations are carried out with high numerical efficiency on a standard desktop computer, requiring no specialized hardware. This demonstrates that WIPL-D provides a complete, practical, and reliable environment for fast, accurate microstrip filter design, making it suitable for academic research and commercial microwave circuit applications.

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Cavity Resonator Filter Modeling Tutorial

This application note demonstrates step-by-step modeling goide of six-cavity filters in WIPL-D Pro CAD. Each cylindrical cavity includes individual tuning screws, with separate screws for inter-cavity coupling adjustment. This document explains modeling using built-in primitives (cylinders, cuboids), transformations (rotate, translate, copy), and complex shapes via sweep. Boolean operations like unite, subtract, imprint, and simplify assemble the blocks into a fully parameterized model ready for tuning or optimization. Basic WIPL-D Pro CAD principles are outlined, with tips for external project modifications via Notepad or MATLAB. The final step adds built-in ports, producing a simulation-ready design suitable for efficient EM analysis and overall efficiency.

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Quadrature Hybrid Coupler Miniaturization

This application note demonstrates compact quadrilateral (branch-line) hybrid directional coupler design using WIPL-D Pro CAD and fast full-wave 3D EM simulation. Built-in primitives and automatic quadrilateral meshing optimized for WIPL-D HOBF enable rapid modeling. Microstrip couplers are simulated in seconds per frequency. Miniaturization halves the size, though detailed artificial transmission lines increase EM complexity; WIPL-D keeps simulation efficient. The model includes losses, metallization thickness, substrate and ground dimensions, and feed positions. Results provide return loss, output power division, input port isolation, and output port phases, ensuring accurate and complete EM characterization for modern compact couplers.

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Divider in Substrate Integrated Waveguide Technology

This application shows WIPL-D’s capabilities for full-wave EM simulation of a substrate-integrated waveguide divider at 60 GHz. Using WIPL-D Pro CAD, the CAD model is imported and meshed; its symmetry allows simulating only a quarter, reducing resources and time. The moderate-size model with small details requires just 8,100 unknowns per MoM matrix, solved efficiently on an inexpensive multicore desktop using CPU-only computation.
WIPL-D’s parallelization ensures fast execution. Simulation results include full current distributions for all five ports, highlighting the efficiency and accuracy of WIPL-D for compact waveguide dividers in SIW technology, combining precision, low computational cost, and quick turnaround for advanced EM design.

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Round Rod Interdigital Filter Optimization Using WIPL-D

This application note presents a comprehensive overview of the system’s design, operating principles, and practical performance. It explains the motivation behind the architecture, outlines the key technical choices made during development, and details the methods used to verify functionality under realistic conditions. Special attention is given to component selection, layout considerations, calibration steps, and measurement procedures that influence overall accuracy and stability. By guiding the reader through each stage of the process — from initial concept to validated results — this document aims to provide a clear, reliable reference that supports effective implementation, troubleshooting, and future enhancements of the system.

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