Feature 5: Power Handling Prediction

SynMatrix offers engineers a simple calculation on power handling prediction. By inputing relevant filter information, the maximum power handling ability can be predicted; meanwhile, based on input data, the user still can judge if the filter can be breakdown or not under the specific input power.

A waveguide type filter will be set as an example to show how to use this function; meanwhile a simulated verification will be illustrated to prove the result.

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: Single cavity design. Design a single cavity until it can fulfill the targeted frequency-frequency range and unloaded Q.

Step 3: Single cavity design---Inband. The max E file needs to be obtained by investigating two frequencies: the center frequency and the band edge (where the maximum breakdown happens)

Step 4: Obtain the stored energy.

Step 5:Input the corresponding parameter in SynMatrix.

Single cavity design---At band edge 14.84GHz:

Other parameters to be concerned about:

  1. Load mismatch.
    1. the load mismatch may cause the standing wave in the filter, which may decrease the filter power handling capability
    2. Assuming the reflected coefficient at the load is Γ, the load mismatch factor will be (1- Γ)^2
    3. At the center frequency, the power handling capability is 37,755W. Considering the reflected coefficient Γ, the actual power handling level is about 35,489 - even worse at the band-edge due to the large reflected power
  2. Pressure and Temperature. Temperature and pressure are critical factors to determine power handling capability. Filter power handling capability will be decreased under the low pressure and high temperature conditions. Although the simulation cannot find the best solution, it may draw attention during the design process.