Filter design at millimeter-wave frequencies can be time-consuming and challenging, especially when it comes to achieving the required performance in both simulation and manufacturing. Traditional design approaches often require multiple iterations and extensive optimization cycles, making development costly and lengthy.
SynMatrix offers a streamlined workflow for creating, optimizing, and fine-tuning filters across a wide range of topologies and frequency ranges, significantly reducing design time while maintaining high-performance standards.
In this blog, we demonstrate how SynMatrix is used to design a 5th-order single-band substrate integrated waveguide (SIW) bandpass filter operating at 28 GHz. The process covers everything from the initial specifications to the final optimization.
Filter Synthesis:
Start with the synthesis process by defining the filter parameters, including order, return loss across the band, bandwidth, and other key specifications. For this example, we set the filter order to 5, return loss to 25 dB, center frequency to 28 GHz, and bandwidth to 0.56 GHz. No transmission zeros are added in this case, and the return loss and rejection requirements are specified as shown below.
The coupling Matrix is:
3D Modeling:
Navigate to 3D Modeling and select Cavity. You will see several options: coaxial, rectangular waveguide, circular waveguide, SIW, and planar coupled resonator. Choose SIW, then confirm and start a new design.
1. Frequency and Q Analysis:
For this filter, a hexagonal configuration is used. The selected substrate is Ultralam 1217 (tm) with a via diameter of 0.171 mm.
2. Single Cavity:
The single cavity parameters are shown below:
Based on the coupling matrix, the required resonant frequency for all resonators is approximately 27.998 GHz. A parametric sweep is performed for the tuning depth from 0.65 mm to 0.7 mm, and the estimated tuning depth for the target frequency is 0.678 mm.
3. Coupling Scheme:
The edge window coupling is selected as the main coupling method, as shown below:
A parametric study of the iris width is conducted from 1.5 mm to 1.8 mm, with the estimated values for each coupling shown below:
4. Input / Output:
A coplanar configuration is used for the input and output. The tuning depth is set to 0.66 mm, insertion depth to 0.77 mm, and branch length to 0.65 mm.
A parametric study is run for the branch length from 0.5 mm to 1.0 mm. With a target group delay of 0.905 ns, the estimated optimal branch length is 0.62 mm.
5. Full 3D Modeling:
At this stage, all estimated values are applied to the main body design. Because this filter does not include a cross-coupled structure, that step can be skipped. The simulation setup is shown below:
The initial filter response is shown below:
SynMatrix’s custom optimization and AI optimization are then used to tune and refine the filter. The final results are shown below:
The video below walks through all the steps in detail, and the filter model is available in the downloadable resources.
Downloadable Resources
28 GHz SIW Filter
Ozen Engineering Expertise
Ozen Engineering Inc. leverages its extensive consulting expertise in CFD, FEA, optics, photonics, and electromagnetic simulations to achieve exceptional results across various engineering projects, addressing complex challenges such as antenna design, signal integrity, electromagnetic interference (EMI), and electric motor analysis using Ansys software.
We offer support, mentoring, and consulting services to enhance the performance and reliability of your electronics systems. Trust our proven track record to accelerate projects, optimize performance, and deliver high-quality, cost-effective results. For more information, please visit https://ozeninc.com.
If you want to learn more about our consulting services, please visit: https://www.ozeninc.com/consulting/
CFD: https://www.ozeninc.com/consulting/cfd-consulting/
FEA: https://www.ozeninc.com/consulting/fea-consulting/
Optics: https://www.ozeninc.com/consulting/optics-photonics/
Photonics: https://www.ozeninc.com/consulting/optics-photonics/
Electromagnetic Simulations: https://www.ozeninc.com/consulting/electromagnetic-consulting/
Thermal Analysis & Electronics Cooling: https://www.ozeninc.com/consulting/thermal-engineering-electronics-cooling/