Home / Examples / Electromagnetic Analysis [Hertz] / Example 5: Cavity Resonator

Example 5: Cavity Resonator

General

The model is a cavity resonator (1/4 wavelength coaxial).
The filtering characteristics of the resonator are solved.
Unless specified in the list below, the default conditions will be applied.

[How to Reduce the Calculation Time]

Analysis Space

Item	Settings
Analysis Space	3D
Model Unit	mm

Analysis Conditions

Item	Settings
Solver	Electromagnetic Analysis [Hertz]
Analysis Type	Harmonic Analysis

The harmonic analysis is set up as follows.

Tabs	Setting Item	Settings
Mesh Tab	Element Type	2nd-order Element
	Multigrid/Adaptive Mesh Method	Select [Apply adaptive meshing].
	Frequency-Dependent Meshing	Reference Frequency: 1x109 [Hz] Select [The conductor bodies thicker than the skin depth constitute the boundary condition]. The surface of Metal is treated as the boundary condition having some loss, as Metal is thicker than the skin depth.
Harmonic analysis	Sweep Type	Select [Linear Step by Division Number]
	Sweep Setting	Minimum: 0.95×109 [Hz] Maximum: 1.05x109 [Hz] Division: 40
	Sweep Setting	Select Fast Sweep S-parameter Tolerance: 1×10-3
	Input	1.0 [W]

Model

The model consists of 2 cavity resonators with one end open. The resonators are coupled through the coupling window and also with the magnetic loop externally.

It is a 2-stage filter.

The whole model

The detail around port

Body Attributes and Materials

The boolean operation is not performed for CAV and METAL,

even though they are overlapping. The boolean will be done automatically during meshing.
Body #4 is an imprinting body and located at the coupling window.

The electric wall boundary condition is set to the body. Wire bodies are created at the ports.
The integral path boundary condition is set on the wire body.

Body Number/Type	Body Attribute Name	Material Name
0/Solid	CAV	000_Air(*)
1/Solid	METAL	008_Cu *
2/Solid	METAL	008_Cu *
3/Solid	CAV	000_Air(*)
4/Sheet	Imprinting body
5/Solid	METAL	008_Cu *
6/Solid	METAL	008_Cu *
8/Solid	CAV	000_Air(*)
9/Solid	METAL	008_Cu *
10/Solid	METAL	008_Cu *
11/Solid	METAL	008_Cu *
14/Solid	METAL	008_Cu *
15/Solid	CAV	000_Air(*)

* Available from the material DB

Boundary Conditions

The port boundary conditions (PORT1, PORT2) are set on the ports of the filter.
The integral path is required between the hot and the ground for two-conductor ports.

The integral path is used to calculate the characteristic impedance of the port.

S-parameters can be converted based on the characteristic impedance.

Boundary Condition Name/Topology	Tab	Boundary Condition Type	Settings
PORT1/Face	Electric	Port	Reference Impedance: Select [Specify] and enter 50 [Ohm]. Number of Modes Number of Precalculated Modes: 5 Number of Modes Used in the Actual 3D Analysis: 1 Select Modes: None
PORT2/Face	Electric	Port	Same as PORT1
EW/Face	Electric	Electric Wall
MW/Face	Electric	Magnetic Wall
Outer Boundary Condition	Electric	Electric Wall

The outer boundary of air:

The boundary between air and Metal is the lossy conductor surface of the material of Matal.
The outer boundary of Air, which does not have any boundary conditions and is adjoining with the exterior, is set with
the electric wall, representing a perfect conductor.

Results

The S-parameters plots are shown below.

The pass band is around 1.01 [GHz].