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 A Level     Wireless     Bands     >Wave Calculations<

# Wireless Wave Calculations

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A Level    Wireless Transmission    Questions 0 to 11   -->  View All

### Calculating The Wavelength

• Speed of Light = Frequency * Wavelength
• C = F λ
• λ = C / F

### Calculating The Frequency

• Speed of Light = Frequency * Wavelength
• C = F λ
• F = C / λ
• C = 3x108 ms-1 for radio waves. For sound, it's 330 ms-1

### Antennas

• The most common types of antenna have a wire or rod that is half a wavelength long.
To find the best size, calculate the wavelength and divide by two.
This is called a DIPOLE.
• Directional antennas have multiple conductors in the classic TV aerial shape.
The length is still half a wavelength.
• Dish antennas use a reflector to concetrate the energy.
At the focal point of the dish is a normal but small antenna.
• Quarter wave antennas are common.
These rely on a reflecting surface such as the metal body of a vehicle or the earth itself.
The missing half of the antenna is "mirrored" in the reflecting surface.

### Polarisation

• The orientation of the electric Field. (Horizontal, Vertical, Circular or Random for light photons).

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