Example3 Antenna with Impedance-Matching Components

General

  • The characteristics of a spiral antenna connected to impedance-matching components are analyzed.
     

  • The impedance characteristics and radiation patterns are obtained.
     

  • 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

Solvers

Electromagnetic Analysis [Hertz]

Analysis Type

Harmonic analysis

Options

Select “Ignore the influence of face/edge electrode thickness” *

* This is the default setting. There are no face electrodes with this model. Therefore it is irrelevant to select it or not.

 

Mesh tab, Harmonic analysis tab and Open boundary tab are set as follows.

Tabs

Setting Item

Settings

Mesh Tab

Element type

2nd-order element

Multigrid/Adaptive Mesh Method

Select [Use the adaptive mesh method].

Frequency-Dependent Meshing

Reference frequency: 1.5×10^9[Hz]

Select “The conductor bodies thicker than the skin depth constitute the boundary condition.”

Harmonic analysis

Frequency

Minimum: 1×10^9[Hz]

Maximum: 2×10^9[Hz]

Sweep Type

Select “Linear step”

Division number: 100

Sweep Setting

Select Fast sweep

S-parameters variation: 1×10^-3

Input

1.0[W]

Open boundary

Type

Absorbing boundary

Order of Absorbing Boundary

1st degree

 

Model

The spiral antenna is formed with a conductive strip wound around the alumina (ANTENNA) . It is mounted on a substrate (SUB) made of glass epoxy. A port (P1) is set at the feeding point of the spiral antenna.

Two inductors are inserted as impedance-matching components near the feeding point. The air (AIR) encloses the substrate and the antenna entirely.

The open boundary condition is set on the surface of “AIR”.

“Conductor wall” is set on antenna and substrate electrodes (EC) as boundary condition. Inductors are set with “Lumped constant” boundary condition.

 

 

 

Body Attributes and Materials

Body Number/Type

Body Attribute Name

Material Name

0/Solid

ANTENNA

001_Alumina *

1/Solid

SUB

006_Glass_epoxy *

9/Solid

AIR

000_Air(*)

* Available from the Material DB

 

Boundary Conditions

Boundary Condition Name/Topology

Tab

Boundary Condition Type

Settings

PORT/Face

Electric

I/O Port

Reference Impedance: Select “Specify”
and enter 50[Ohm].

Number of Modes

Number of precalculated modes: 5

Number of modes used in the actual analysis: 1

Select modes: none

L1/Face

Electric

Lumped constant

2.0×10^-9[H]

L2/Face

Electric

Lumped constant

4.0×10^-9[H]

EC

Electric

Conductor wall

Conductivity: 1.0×10^7[S/m]

Outer Boundary Condition

Electric

Open boundary

 

 

Results

The calculated impedance characteristics of this antenna is shown below.

 


 

The radiation pattern of this antenna is plotted with the polar graph below. The unit is [dB].

  • To calculate this radiation pattern, the following conditions have been applied.

    * Frequency: 1.5×109[Hz] (Single frequency)

    * Deselect “Fast sweep”.

  • See [Exercise 7: Dipole Antenna].

  • See also [Electromagnetic Waves Directivity].

 

φ=0[deg], θ=0-360[deg], 60 steps

φ=90[deg], θ=0-360[deg], 60 steps

 

Electromagnetic Waves Directivity