Feature 3: CAT Application

Computer aided tuning was introduced first in the satellite filter industry, and has now been widely adopted to the wireless field. It applies systematic approaches based on either reconstruct filter polynomial, curve fitting or by optimization circuit model to fit and match simulation or measurement responses.

As the world’s first online CAT software, Synmatrix applies a proprietary algorithm to incorporate the dispersive effect and spurious prediction to streamline repetitive and time-consuming filter design work, offering engineers and technicians a fast and accuracy result.


Example 1: 9 poles with 3 transmission zeros coaxial structure


Specifications: Filter order=9; f0=1958.5Mhz; BW=67Mhz; RL=23dB; Transmission zeros: 1890MHz, 1905MHz, 1910MHz

Step 1: Input the filter specs and obtain the corresponded topology and coupling matrix.


Step 2: Analyze the matrix stability. The user can analyze the matrix stability by using Monte-Carlo(MC) analysis in the “Tool Box”, especially for transmission zeros due to their extreme low level only at one side.

From the MC analysis*, it can be seen that Cascade Quadruplet(CQ) structure is more sensitive than the Cascade Triplet(CT).


Step 3: Single cavity analysis and coupling coefficient calculation. For more details, please refer to “Microwave Filter for Communication System”.


Step 4: Build the model and obtain the initial response. To mitigate the design difficulty, the user can start from Chebyshev type filter by removing all transmission zeros.


Step 5: Start the iterated optimization procedures.

Add cross coupling M24: Since the M24 is very stable and more so than M57 and M58 analyzed in step 2, it will be first introduced to the full 3D model:



Example 2: 7 poles with 3 transmission zeros WG structure


Specifications: Filter order=7; f0=14.35GHz; BW=0.9GHz; RL=23dB;12.5~13.1GHz<-80dB; 13.1~13.5GHz<-40dB; 13.5~13.8GHz<-25dB; 15~15.5GHz<-35dB

Step 1: Input the filter specs and obtain the corresponded topology and coupling matrix


Step 2: Analyze the matrix stability. The user can analyze the matrix stability by using Monte-Carlo(MC) analysis in the “Tool Box”, especially for transmission zeros due to their extreme low level on one side.

Within 1% variation analysis, filter performance looks very stable. The 3D model can now be constructed.


Step 3:Single cavity analysis and coupling coefficient calculation. For more details, please refer to “Microwave Filter for Communication System”.


Step 4:Build the model and obtain the initial response.


Step 5: Start the iterated optimization procedures



Limitation of CAT:
  • Any variation in the coupling values with frequency dispersion or spurious impacts can lead to a change of the coupling-matrix.
  • Due to the dispersive effect and/or spurious impaction, most CAT software will be limited, resulting in inaccurate results or even failure on capturing.



SynMatrix Benefits:
  • SynMatrix offers the Dispersion Function which can assist the CAT process to fit the simulation or measured result
  • During the optimization, the “Golden Matrix” needs to be re-calibrated to meet the design specifications until it converges to a stable condition