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Naval Weapons Systems

Naval Weapons Systems. Energy Fundamentals. Learning Objectives. Comprehend basic communication theory, electromagnetic (EM) wave theory Comprehend radar and radio wave parameters including frequency, period, wavelength, velocity, and amplitude

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Naval Weapons Systems

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  1. Naval Weapons Systems Energy Fundamentals

  2. Learning Objectives • Comprehend basic communication theory, electromagnetic (EM) wave theory • Comprehend radar and radio wave parameters including frequency, period, wavelength, velocity, and amplitude • Know Maxwell’s theory, relationship between wave parameters • Comprehend concepts of time and distance (wave phase angle) and interference

  3. Learning Objectives (cont) • Know EM wave propagation principles such as reflection, refraction, diffraction, and ducting • Know the definition of sky, space, and ground waves

  4. Cycle Amplitude 1 second Energy Fundamentals • RAdio Detection And Ranging • Radar is an electromagnetic wave that acts like any other electromagnetic wave (i.e. - radio, light, etc.) • Characteristics of a radio wave assuming a frequency of 2 Hertz:

  5. Traveling Wave Characteristics • Frequency • Period • Wavelength • Velocity • Amplitude

  6. Maxwell’s Theory • An accelerating electric field will generate a time-varying magnetic field. • A time-varying magnetic field will generate a time-varying electric field. • ...and so on...and so on...and so on... Electric Field Magnetic Field Electric Field

  7. Formation of Electric and Magnetic Fields around an Antenna E-line Mag field e- e- e- Electric field | Magnetic Field | Direction of Propagation.

  8. Electromagnetic Spectrum

  9. Propagation Paths of E-M Waves • Reflection • Refraction • Diffraction

  10. ...Reflection... Phase shift = 180 degrees. Angle of incidence = Angle of reflected wave. Reflected Wave IncidentWave

  11. ...Refraction... • Incident wave passes through two transparent media in which the velocity of light differs... • Incident wave divides into a reflected wave and a refracted wave. • The result is that the energy ray will bend toward the area of higher density.

  12. Snell’s Law n1 * Sin θ1 = n2 * Sin θ2

  13. island not detected ...Diffraction... ...plane waves traveling in a straight path bend around a boundary or obstruction. detected

  14. Wave Propagation – Distance and Frequency • Ground Waves • Sky Waves • Space Waves

  15. Ground Wave... • E-M energy travels along earth’s surface • Very low frequencies, 5-10Khz • Extremely long wavelengths • Shore communications stations (HF-DF)

  16. Sky Wave... • E-M energy refracts toward earth’s surface in upper ionosphere layer • E-M energy then reflects back toward upper layer again • Frequencies to 550 KHz effectively • Fairly long wavelengths • Ship and Aircraft Communications

  17. Space Wave... • E-M energy refracts back toward earth’s surface in outer space (i.e. stratosphere) • Above 30 MHz, ionosphere will not refract E-M waves back toward earth.

  18. Transmission Range Factors • Antenna Height • Target Height • Ducting • Losses • Spreading • Absorption • Constructive Interference • Destructive Interference

  19. Modulation • The process of encoding “Carrier Wave” • “Carrier Wave” has 3 independent parameters • Amplitude • Frequency • Phase

  20. WHEW!

  21. Questions?

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