IV. 실습 보고서

1. Two-element Yagi antenna

Frequency: 300MHz(wavelength 1m)

Feed gap: 0.01 wavelength

 

http://ael.cbnu.ac.kr/study/antenna/antenna-lecture/yagi-antenna/Yagi-antenna.files/image120.jpg

그림: 급전기와 지향기에 의한 방사패턴. 급전기 길이0.47λ, 급전기-지향기 간격0.20λ, 도선 직경0.01λ

 

For the director length of length 0.42 wavelength:

1) Plot the antenna geometry.

2) Plot the Dabs polar pattern on the E plane(zx-plane). Scale: max. 10dB, min. –15dB.

 

(해답)

1) Plot the antenna geometry.

(1) Make a project template.

Project Template

New Template, Microwaves & RF / Optical, Anennas

Create Project Template: Wire, Time Domain

Units: default(mm, GHz)

Frequency Min. : 0.09GHz

Frequency Max. : 0.6GHz

Monitors: E-field, H-field, Farfield

Defined at: 0.3GHz

Template name: Yagi antenna

Feed gap= 10mm

 

(2) Write the parameter 

 

A. Make Dipole wire using parameter symbols.

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

Outer radius: d/2, Inner radius: 0

Y center:0      Z center:0

X min: -L1/2      X max : L1/2

 

 

Material : PEC

B. Make Director wire using parameter symbols.

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

Outer radius: d/2, Inner radius: 0

Y center:0      Z center:s1

X min: -L2/2      X max : L2/2

Material : PEC

 

 

C. Make a feed gap

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

Outer radius: d/2, Inner radius: 0

Y center:0      Z center:0

X min: -g/2      X max : g/2

Material : Vacuum

 

     

 

Shape intersection: Cut away highlighted shape

 

(3) Add an antenna source. Set up a discrete port.

Specify the surfaces between which a discrete port is to be applied.

Modeling

Picks, Pick Points, Pick Face Center

Place the mouse point on the one of gap faces and then double click.

 

 

(4) Simulate

Simulation, Setup Solver, Start

 

 

2) Plot the Dabs polar pattern on the E plane(zx-plane). Scale: max. 10dB, min. –15dB.

 

 

Change the director length from 0.36 wavelength to 0.50 wavelength in 10 steps.

3) Plot the maximum directivity(dB) versus the director length.

 

 

Post-Processing, Result Templates Tools

General Result

- Farfield and Antenna Properties

- Farfield Result

 

 

Max gain at selected frequency             

 

 

Max gain at selected frequency, Front-to-back ratio

           

 

 

Home, Parameter Sweep

New Sequence1, New Parameter Sweep

 

 

 

Start

Navigation Tree, Tables, 0D results

 

 

 

4) Plot the front-to-back ratio(dB).

 

 

For the director length of 0.48 wavelength:

5) Plot the Dabs polar pattern on the E plane(zx-plane). Scale: max. 10dB, min. –15dB.

 

 

2. Three-element Yagi antenna

Frequency: 300MHz(wavelength 1m)

Feed gap: 0.01 wavelength

 

http://ael.cbnu.ac.kr/study/antenna/antenna-lecture/yagi-antenna/Yagi-antenna.files/image124.jpg

그림: 반사기+급전기+지향기 구조의 방사패턴. 급전기 길이 0.47λ, 반사기 길이 0.48λ, 지향기 길이 0.44λ 도선간 간격 0.20λ, 도선 직경 0.01λ

 

For the reflector length of 0.48 wavelength:

1) Plot the antenna geometry.

 

Write the parameter 

 

 

Make Reflector wire using parameter symbols.

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

Outer radius: d/2, Inner radius: 0

Y center:0      Z center:-s1

X min: -L3/2      X max : L3/2

Material : PEC

 

 

Simulate

Simulation, Setup Solver, Start

 

 

2) Plot the Dabs polar pattern on the E plane(zx-plane). Scale: max. 10dB, min. –15dB.

 

 

Change the reflector from 0.38 to 0.58 wavelength in 10 steps.

3) Plot the maximum directivity(dB) versus the director length. Scale: max. 10dB, min. –15dB.

 

Home, Parameter Sweep

New Sequence1

 

 

 

 

4) Plot the front-to-back ratio(dB).

 

 

3. 11-Element Yagi Antenna

ㅇ 안테나 치수 결정

- K7MEM 야기 안테나 설계 프로그램에 접속하여 아래와 같이 설정

     K7MEM Yagi Antenna Design: http://www.k7mem.com/Ant_Yagi_VHF_Quick.html

 

- 주파수: 700MHz

- 이득: 12dBd = 12 + 2.15 = 14.15dBi

- Reflector spacing: 0.20 wavelength(DL6WU)

- Director element spacing: DL6WU spacing

- Boom type: Non-metallic boom

- Boom diameter: 0mm

- Driven element diameter: 8mm

- Parasitic element diameter: 8mm

- Design/Example Viewing: Metric

 

위와 같이 설정 후 [View The Design] 클릭하여 다음 그림과 같은 결과를 얻는다.

Boom은 비금속 직경 0mm로 하였기 때문에 존재하지 않는다 (그림에는 있지만).

 

1) 700MHz 12dBd 야기 안테나 설계결과 제시

급전 다이폴 길이 대 파장: 200.6/428.6 = 0.467

급전 다이폴 길이대 직경비: 200.6/8 = 25

 

ㅇ 설계한 야기 안테나 특성해석: CST Studio 사용

- 좌표축: 야기 안테나 축 = z 축, 도선 축 = x 축과 평향

- 도선을 PEC 원통(내부가 꽉 찬)으로 하여 위에서 설계한 야기 안테나의 형상 생성

- 급전기 중간 급전용 간격: 8mm 제거(도선 직경과 동일)

 

2) 700MHz 12dBd 야기 안테나 형상 제시

3) |S11|(dB) 반사계수 도시: 400-1100MHz, -30dB to 0dB

4) 700MHz에서 Dabs 전계면 polar 패턴 그래프 제시: phi = 0º, theta = 변수, -35dB to 15dB

5) 700MHz에서 Dabs 자계면 polar 패턴 그래프 제시: phi = 0º, theta = 변수, -35dB to 15dB

6) 700MHz에서 설계한 야기 특성분석

     최대이득 = (     )dBi

     전계면 빔폭 = (     )°

     자계면 빔폭 = (     )°

     전후방비 = (     )dB

7) 주파수에 따른 최대이득 도시: 400-1000MHz범위에서 50MHz 간격으로, 수직축 0-20dBi 범위

 

1) 700MHz 12dBd 야기 안테나 설계결과 제시

K7MEM Yagi Design Page 접속, http://www.k7mem.com/Ant_Yagi_VHF_Quick.html

단위 수정, 수치 입력

 

 

 

소자 위치와 소자길이 표시됨.

결과 도시

 

 

2) 700MHz 12dBd 야기 안테나 형상 제시

 

 (1) Make a project template.

Project Template

New Template, Microwaves & RF / Optical, Anennas

Create Project Template: Wire, Time Domain

Units: default (mm, GHz)

Frequency Min. : 0.4GHz

Frequency Max. : 1.1GHz

Monitors: E-field, H-field, Farfield

Defined at: 0.7GHz

Template name: Yagi antenna

 

(2) Make a dipole antenna structure.

Write the parameter 

 

 

A. Make Reflector wire using parameter symbols.

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

Outer radius: d/2, Inner radius: 0

Y center:0      Z center:0

X min: -L1/2      X max : L1/2

Material : PEC

 

B. Make Dipole wire using parameter symbols.

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

Outer radius: d/2, Inner radius: 0

Y center:0      Z center:s1

X min: -L2/2      X max : L2/2

Material : PEC

 

 

 

C. Make D1-D9 (Directors) wire using parameter symbols.

 

  

 

 

 

 

 

 

 

 

D. Make a feed gap

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

Outer radius: d/2, Inner radius: 0

Y center:0      Z center:s1

X min: -g/2      X max : g/2

Material : Vacuum

 

   

 

Shape intersection: Cut away highlighted shape

 

(3) Add an antenna source. Set up a discrete port.

A. Specify the surfaces between which a discrete port is to be applied.

Modeling

Picks, Pick Points, Pick Face Center

Place the mouse point on the one of gap faces and then double click.

 

(4) Simulate

Simulation, Setup Solver, Start

 

 

 

3) |S11|(dB) 반사계수 도시: 400-1100MHz, -30dB to 0dB.

 

 

4) 700MHz에서 Dabs 전계면 polar 패턴 그래프 제시: phi = 0º, theta = 변수, -35dB to 15dB

 

 

5) 700MHz에서 Dabs 자계면 polar 패턴 그래프 제시: phi = 0º, theta = 변수, -35dB to 15dB

 

 

6) 700MHz에서 설계한 야기 특성분석

     최대이득 = (   14.8 )dBi

     전계면 빔폭 = (   34.6  )°

     자계면 빔폭 = (  37.6   )°

     전후방비:  14.8 - (-5) = 19.8dB

 

7) 주파수에 따른 최대이득 도시: 400-1000MHz범위에서 50MHz  간격으로, 수직축 0-20dBi 범위

Field Monitors, double click the farfield (f=0.7)

Check the Transient Broadband

Samples: 15 with (50MHz)

 

Make a farfield (broadband)

 

 

Apply, Ok

 

Simulate

Simulation, Setup Solver, Start

Post-Processing, Result Templates,

 

 

Ok

 

 

Evaluate