Antenna Design, Monopole Antenna

III. Laboratory Report

1. A half-wave dipole in free space

Wire end-to-end length (including the feed gap) = 182

Wire diameter = 4

Feed gap = 2

Frequency range: 400-1200 MHz

Field monitor: Farfield at the resonant frequency of each antenna (to be added later)

1) Draw the antenna geometry.

(Using the CST Studio Suite)

(1) Make a PEC cylinder

Modeling, Cylinder icon, ESC key, Name: solid1, Orientation: Z

Outer radius: 2, Inner radius: 0

Xcenter: 0, Ycenter: 0

Zmin: -182/2, Zmax: 182/2

Material: PEC

(2) Make a feed gap

Modeling, Cylinder icon, ESC key, Name: solid1, Orientation: Z

Outer radius: 2, Inner radius: 0

Xcenter: 0, Ycenter: 0

Zmin: -2/2, Zmax: 2/2

Material: Vacuum

Shape intersection: Cut away highlighted shape

3) Add a discrete port source

Modeling, Pick Points, Pick Face Center, select one of the gap faces (double click)

Pick Points, Pick Face Center, select the other face (double click)

Simulation, Discrete Port

4) Set up the simulation

Define the simulation frequency:

Simulation, Frequency, Min. frequency: 0.4, Max. frequency: 1.2

Set up the field monitor:

Simulation, Field Monitor, E-field, Frequency, Frequency: 0.74, Apply

Simulation, Field Monitor, H-field and Surface current, Frequency, Frequency: 0.74, Apply

Simulation, Field Monitor, Far field/RCS, Frequency, Frequency: 0.74, Apply

5) Define the mesh density if you run out of a computer memory.

Simulation, Global Properties,

Cells per wavelength: 5

Cells per max model box edge: 5

Fraction of maximum cell near to model: 5

6) Simulation

Simulation, Setup Solver

2) Plot |S11| (dB) and add an 'Axis Marker' to find the frequency for minimum |S11| (dB).

Center frequency = 741 MHz

Remove the 'Axis Marker' and add 'Measure Lines' at |S11| (dB) = -10 dB.

Bandwidth = 86 MHz

(1) Add a 'Axis Marker'.

1D Results, S-Parameters, S1,1

RESULT TOOLS - 1D Plot, dB

Mouse right click: show axis marker

(2) Add 'Measure Lines'.

Mouse right click: show measure line

3) Plot Rin and Xin on a same graph with 'Axis Marker' at Xin = 0. Find the resonant frequency (for Xin =0) and the resonant resistance (for Xin = 0). Express the dipole length in the resonant wavelength.

Resonant frequency = 751 MHz

Resonant resistance = 67 ohms

Dipole length in wavelength: wavelength = 300/0.751 = 399, Dipole length = 182/399 = 0.456 wavelength

RESULT TOOLS - 1D Results, Z Matrix, Z11, 1D Plot, Real/Imag

Mouse right click: show axis marker

Adjusting: Z1,1(Im) =0

4) Plot Gtheta in 3D at resonant frequency and find the maximum gain.

Gmax = 2.18 dBi

Farfields, farfield (f=0.74) [1], Abs, FARFIELDS - Farfield Plot, Show Structure, 3D

Gmax =2.18dBi

2. A quarter-wave monopole on an infinite ground plane

Wire length (except the feed gap) = 90

Wire diameter = 4

Feed gap = 1

Frequency range: 400-1200 MHz

Field monitor: Farfield at 770 MHz

1) Make the antenna geometry and plot it in 3D.

(1) Make a monopole wire.

Modeling, Cylinder 아이콘 선택, ESC 키, Name: solid1, Orientation: Z

Outer radius: 2, Inner radius: 0

Xcenter: 0, Ycenter: 0

Zmin: 1, Zmax: 90

Material: PEC

(2) Make an infinite PEC (Et = 0) ground plane on the Zmin (z = 0) boundary box.

Simulation, Boundaries, Boundary Conditions, Zmin: choose the electric(Et=0), OK

(3) Define a discrete port.

Modeling, Pick Points, Pick Face Center, select a face in the gap and double click

Pick Points, Pick Face Center, select the other face in the gap and double click

Pick Point, Pick point from coordinates

Simulation, Discrete Port

(4) Setup the simulation.

Set the frequency:

Simulation, Frequency, Min. frequency: 0.4, Max. frequency: 1.2

Set the field monitor:

Simulation, Field Monitor, E-field, Frequency, Frequency:0.77, Apply

Simulation, Field Monitor, H-field and Surface current, Frequency, Frequency:0.77, Apply

Simulation, Field Monitor, Far field/RCS, Frequency, Frequency:0.77, Apply

(5) Simulate.

Simulation, Setup Solver

2) Plot |S11| (dB) and add an 'Axis Marker' to find the frequency for minimum |S11| (dB).

Center frequency = 783 MHz

Remove the 'Axis Marker' and add 'Measure Lines' at |S11| (dB) = -10 dB.

Bandwidth = 139 MHz

1D Results, S-Parameters, S1,1

RESULT TOOLS - 1D Plot, dB

Mouse right click: show axis marker

Mouse right click: show measure line

Resonant frequency = 760 MHz

Resonant resistance = 35 ohms

Dipole length in wavelength: wavelength = 300/0.76 = 395, Monopole length = 91/395 = 0.230 wavelength

RESULT TOOLS - 1D Results, Z Matrix, Z11, 1D Plot, Real/Imag

Mouse right click: show axis marker

Adjusting: Z1,1(Im) =0

4) Plot Gtheta in 3D at the resonant frequency and find the maximum gain.

Gmax = 5.22 dBi

Farfields, farfield (f=0.77 [1], Abs, FARFIELDS - Farfield Plot, Show Structure, 3D

3. An inverted L antenna on an infinite ground plane

Wire length: vertical = 30, horizontal = 60

Wire diameter = 4

Feed gap = 1

Frequency range: 400-1200 MHz

Field monitor: None

1) Make the antenna geometry and plot it in 3D.

(1) Make an infinite ground plane.

File, New and Recent, New Template, Great Project Template, MICROWAVES & RF/OPTICAL, Antennas, Planar(Patch, Slot, etc,), Time Domain, Next

Frequency Min: 0.4 GHz

Frequency Max: 1.2 GHz

Monitors: not selected

Define at: not entered

Template Name: Inverted Antenna , Finish

Simulation, Boundaries, Boundary Conditions, Zmin: choose the electric (Et=0), OK

(2) Make an inverted L antenna

Modeling, Cylinder, ESC key, Name: solid1, Orientation: Z

Outer radius: 2 Inner radius: 0.0

X center: 0 Y center: 0

Z min: 1 Z max:31

Material: PEC

Modeling, Cylinder, ESC key, Name: solid2, Orientation: X

Outer radius: 2 Inner radius: 0.0

Y center: 0 Z center: 31

X min: -58 X max: 2

Material: PEC

(3) Make a discrete port.

Modeling, Pick Points, Pick Face Center, select a face in the gap and double click.

Modeling, Pick Points, Pick Point From Coordinates

Enter 3D point, X:0, Y: 0, Z:0 OK

Simulation, Discrete Port, OK

Simulation, Setup Solver

2) Plot |S11| (dB).

1D Results, S-Parameters, S1,1

RESULT TOOLS - 1D Plot, dB

Right click, Plot Properties, Auto range deselected

3) Plot Rin and Xin on a same graph with 'Axis Marker' at Xin = 0. Find the resonant frequency (for Xin =0) and the resonant resistance (for Xin = 0).

Resonant frequency = 825 MHz

Resonant resistance = 12 ohms

RESULT TOOLS - 1D Results, Z Matrix, Z11, 1D Plot, Real/Imag

Mouse right click: show axis marker

Adjusting: Z1,1(Im) =0

4) Plot Gtheta in 3D at the resonant frequency and find the maximum gain.

Gmax = 4.21 dBi

Farfields, farfield (f=0.825) [1], Theta,

Far Field Properties, Plot mode, plot mode and scaling, choose the gain (IEEE)

4. An inverted F antenna on an infinite ground plane

Wire length: vertical = 30, horizontal = 60

Wire diameter = 4

Feed gap = 1

Frequency range: 400-1200 MHz

Field monitor: Farfield at 800 MHz

Shorted-wire to feed-wire gap (S) = 1, 2, 4, 8 (Use the parameter sweep)

1) Draw the antenna geometry.

(1) Make a template. Define an infinite ground plane.

File, New and Recent, New Template, Great Project Template, MICROWAVES & RF/OPTICAL, Antennas, Planar(Patch, Slot, etc,), Time Domain, Next

Frequency Min: 0.4 GHz

Frequency Max: 1.2 GHz

Monitors: check the E-field, H-field, Farfield, Power loss

Define at: 0.8 GHz, Next

Template Name: Inverted Antenna , Finish

Simulation, Boundaries, Boundary Conditions, Zmin: choose the electric(Et=0), OK

~~Modeling,~~ 고리 ~~실린더~~ ~~(Cylinder)~~ 선택~~, ESC~~ 키~~, Name: solid1, Orientation: Z~~

~~Outer radius: 2 Inner radius: 0.0~~

~~X center: 0 Y center: 0~~

~~Z min: 1 Z max:31~~

~~Material: PEC~~

~~Modeling,~~ 고리 ~~실린더~~ ~~(Cylinder)~~ 선택~~, ESC~~ 키~~, Name: solid2, Orientation: X~~

~~Outer radius: 2 Inner radius: 0.0~~

~~Y center: 0 Z center: 31~~

~~X min: -58 X max: 2~~

~~Material: PEC~~

~~Modeling,~~ 고리 ~~실린더~~ ~~(Cylinder)~~ 선택~~, ESC~~ 키~~, Name: solid3, Orientation: X~~

~~Outer radius: 2 Inner radius: 0.0~~

~~Y center: 0 Z center: 31~~

~~X min: 2 X max: 4+s~~

~~Material: PEC~~

~~Modeling,~~ 고리 ~~실린더~~ ~~(Cylinder)~~ 선택~~, ESC~~ 키~~, Name: solid4, Orientation: Z~~

~~Outer radius: 2 Inner radius: 0.0~~

~~X center: 4+s Y center: 0~~

~~Z min: 1 Z max:33~~

(3) Make a discrete port

Modeling, Pick Points, Pick Face Center, gap 한면에 마우스 위치후 더블클릭

Modeling, Pick Points, Pick Point From Coordinates

Enter 3D point, X:0, Y: 0, Z:0 OK

Simulation, Discrete Port, OK

(4) Simulate.

Simulation, Setup Solver, Start

2) Plot |S11| (dB) for five cases on a same graph.

(1) Setup a parameter sweep.

Simulation, Setup Solver, Time Domain Solver Parameters, Par. Sweep,

New Sequence, New Parameter, Parameter Sweep Parameter

(2) Setup the output plot.

Post-Processing, Result Templates Tools, General 1D, choose the 0D or 1D result from 1D Result (Rescale, Derivation, etc)

(3) Do the parameter sweep.

Evaluate All

Simulation, Setup Solver, Start

0D or 1D result.

(4) Plot |S11| (dB).

1D Results, S-Parameters, S1,1

RESULT TOOLS - 1D Plot, dB