# Exploring Antennas - PowerPoint PPT Presentation

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Exploring Antennas. Van Warren AE5CC. Exploring Antennas: Pattern. D esign S imulate M easure R efine. Exploring Antennas: Rule 1. Don’t reinvent the wheel. Explore and understand successful designs before inventing new ones. Exploring Antennas: 2m.

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Exploring Antennas

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Van Warren

AE5CC

D esign

S imulate

M easure

R efine

## Exploring Antennas: Rule 1

Don’t reinvent the wheel.

Explore and understand successful designs before inventing new ones.

## Exploring Antennas: 2m

Single Most Important Parameter:

Wavelength

Middle of band is 146 MHz

Middle of CW band is 144.05 MHz

## Exploring Antennas: 2m

Middle of band is 146 MHz

146 MHz = 2.053 meters = 6.7 feet = 80.83 inches

Full Wavelength

## Exploring Antennas: 2m

General Purpose 2m Antenna in free space.

## Exploring Antennas: 2m

General Purpose 2m Antenna with Ground Plane (-5 Hz shift)

## Exploring Antennas: 2m

General Purpose Ground Plane Antenna.

## Exploring Antennas: 2m

General Purpose Antenna at 144 MHz In Free Space

## Exploring Antennas: 2m

General Purpose Antenna with Ground Plane at 144 MHz

## Exploring Antennas: 2m

Same Antenna at 900 MHz (33 cm band).

## 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.

Design Antenna

Simulate Antenna

Measure Antenna

Improve

## 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

## Design First Pass: Wire Loop

0.0025 in diameter

Materials 42 AWG 

DX: 1 – 1000 MHz

TX: 80 – 2m

Aesthetic, preferably invisible 

Low Lightning Hazard 

Low Structural Hazard 

Easily Relocated 

Inexpensive 

## Design Pass: Vary Parameters

- Start: 42 AWG - 0.00125” radius

Observe Effects of:

Wire Diameter Variation

Frequency Variation

Loop Geometry Variation

in plane/out of plane elements

- 160, 80, 40, 20, 10, 6, 2, 0.7, 0.3 meters

- 1.9, 3.5, 7, 14, 28, 50, 144, 420, 902 MHz

“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.

Total gain @ 20 MHz

Results suggest a wire loop

Can be “aimed” by simply

Changing the feed point.