双工器

Analysis of a Single Dielectric Resonator

A single resonator cavity is perfect for investigating the proposed approach because solutions can be obtained very fast, and various methods can be used to obtain the same information. 1.Resonant frequency and Q determined from the Eigenmode solver in HFSS. 2.Solve the driven problem with port excitations (also gives resonant frequency and Q) 3. Create a parametric model in HFSS and analyze this model by matching port modes in Ansoft Designer (the transfinite element method).

Many problems can be broken down into constituent parts:

Waveguide and Cavity Filters Large Circuits: package – board - component Any components connected by transmisison lines or waveguides!
高性能腔体滤波器和 双工器的综合设计
High Performance Cavity Filter Design
Authored by: Devin Crawford Ansoft Corporation
Link the Power of Circuit and Finite Element Analysis
Example 1: Waveguide Filter

The waveguide filter is comprised of e-plane irises that have been characterized parametrically in HFSS.
波导滤波器
1 2 3 4 5 Parametric model based on full-wave analysis.
Subdivision of Dielectric Resonators

Eigenmode solver, driven solution, and transfinite element analysis were used to verify the equivalence of the three analysis methods.



Generalized s-parameters fully characterize the “black-box” behavior of a three-dimensional structure. Structures that have identical port solutions, but different internal geometries may often be analyzed separately and joined at the ports. The use of generalized s-parameters that were determined using the transfinite element method insures that the fields are matched at the port boundary. Let’s look at some examples…
|S21|
0 -5 -10 -15 -20 -25 -30 -35 -40 9.5 9.7 9.9 10.1 10.3 10.5
Designer
0 -10 -20 -30
|S11|
HFSS
-40 -50 -60 9.6 9.8 10 10.2 10.4
Frequency (GHz)
Frequency (GHz)
Realization of a Waveguide Filter
0
-10
-20
dBFra Baidu bibliotek
-30
-40
-50 9.5 9.7 9.9 10.1 10.3 10.5 Frequency (GHz)
After optimization using interpolated HFSS solutions, accuracy can be improved by “Simulating missing solutions”

The transfinite element method is used to determine the two-dimensional field solution at the port.
A single port solution (mode) yields a propagation constant γ n = jβ n + α n
S11 (d , ω ) S12 (d , ω ) S (d , ω ) S (d , ω ) 22 21
S-parameters depend on frequency and aperture width.
孔径
d
Realization of a Waveguide Filter
3. Optimization continued: the goal response for the optimization can be generated using the filter synthesis tool. oal g n tio a z i m Opti
Optimized response using interpolation of coarsely spaced HFSS solutions
ssible e c c a s i lysis a n a e v l-wa l u f e h t of ons! i y t c u a l r o u s c sting i x The ac e g n i polat r e t n i y b
Realization of a Waveguide Filter
βn αn
propagation constant attenuation
ˆ E ( x, y )e −γz En = y
…and characteristic impedance (specifies a relationship between E and H)
z
Transfinite Element Method in a Nutshell
Example 2: dielectric/coaxial resonator cavity filter

Waveguide components are generally simple because the behavior is accurately described by single mode interaction between components. How do we approach structures that are not easily described by single mode behavior?


What is the Transfinite Element Method?

The Finite Element method is used to solve Maxwell’s equations in the volume of arbitrary three-dimensional structures.
The model is fully parameterized!
Parameterized Port Impedance

An important aspect of the circuit model is the frequency dependent port impedance:
if(k>kc10,z10,0)
Z10 is the frequency dependent characteristic impedance.
Realization of a waveguide filter
3. Optimize the filter response by “interpolating existing solutions.”
The basic approach
1. 2. 3. 4.
5.
Select the building blocks (parametric models) for the desired structure. Verify the technique on a simple, easily verifiable model. Define the parameter space: what range of values should the parameters cover? Synthesize and optimize the desired three-dimensional structure using parametric models generated from HFSS. Verify the design using the full-wave solution of the entire structure.
Comparison between HFSS and Ansoft Designer
4. Improve the solution accuracy by generating exact full-wave solutions for the optimized parameter values.
1. Define parameterized model by generating a grid of coarsely spaced solutions in the parameter space.
Realization of a Waveguide Filter
2. Create the entire filter from individual components.

The “divide and conquer” strategy leads to very efficient and accurate solutions.
Strategy for combining full-wave three-dimensional solutions

Determine how best to subdivide large problems. Solve the constituent problems parametrically. Construct models from constituent parts. The existence of parametric 3-D models enables fast design and optimization of very large structures!


Use the example of a mixed resonator filter to investigate the approach.
Single Dielectric Resonator
E-field H-field
Perfect Esymmetry plane

As usual, take advantage of the symmetry when possible for full-wave analysis.