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Exploring Antennas Van Warren AE5CC. Exploring Antennas: Pattern D esign S imulate M easure R efine.

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Presentation on theme: "Exploring Antennas Van Warren AE5CC. Exploring Antennas: Pattern D esign S imulate M easure R efine."— Presentation transcript:

1 Exploring Antennas Van Warren AE5CC

2 Exploring Antennas: Pattern D esign S imulate M easure R efine

3 Exploring Antennas: Rule 1 Don’t reinvent the wheel. Explore and understand successful designs before inventing new ones.

4 Exploring Antennas: 2m Middle of band is 146 MHz Middle of CW band is MHz Single Most Important Parameter: Wavelength

5 Exploring Antennas: 2m Middle of band is 146 MHz 146 MHz = meters = 6.7 feet = inches Full Wavelength

6 Exploring Antennas: 2m General Purpose 2m Antenna in free space.

7 Exploring Antennas: 2m General Purpose 2m Antenna with Ground Plane (-5 Hz shift)

8 Exploring Antennas: 2m General Purpose Ground Plane Antenna.

9 Exploring Antennas: 2m General Purpose Antenna at 144 MHz In Free Space

10 Exploring Antennas: 2m General Purpose Antenna with Ground Plane at 144 MHz

11 Exploring Antennas: 2m Same Antenna at 900 MHz (33 cm band).

12 Exploring Antennas: Loops Now duplicate argument using tetrahedral geometry reasoning from the simplex argument and minimal materials and tesselation of sphere for balloon borne 2m antenna. Also reduce to ¼ wave and compare gain with full wavelength cases.

13 Exploring Antennas: Loops Design Antenna Simulate Antenna Measure Antenna Improve

14 Design Antenna: Requirements Use 42 AWG DX: 1 – 1000 MHz TX: 80 – 2m 50 watts Aesthetic, preferably invisible Low Lightning Hazard Low Structural Hazard Easily Relocated Inexpensive

15 Design First Pass: Wire Loop Materials 42 AWG  DX: 1 – 1000 MHz TX: 80 – 2m Aesthetic, preferably invisible  Low Lightning Hazard  Low Structural Hazard  Easily Relocated  Inexpensive  in diameter

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17 Design Pass: Vary Parameters Observe Effects of: Wire Diameter Variation Frequency Variation Loop Geometry Variation – add recursive elements – in plane/out of plane elements - Start: 42 AWG ” radius - 160, 80, 40, 20, 10, 6, 2, 0.7, 0.3 meters - 1.9, 3.5, 7, 14, 28, 50, 144, 420, 902 MHz

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20 Total 20 MHz Results suggest a wire loop Can be “aimed” by simply Changing the feed point. Suggests a new radar antenna. Stationary loop, moving feed point. What is radiative efficiency? “Large” Circular loop has relatively flat frequency response, but surprisingly, high directionality! (front/side ratio) This borders on discovery! Compare with microphone gain patterns and yagi’s or “beam” antennas.

21 Need a program that will let me preprogram a series of mouse positions, clicks and key presses, to create animations of the gain patterns of these loop antennas. These are necessary and wonderful animations.


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