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Definition
| Some disturbance in a parameter that varies over its spatial dimensions. |
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| The movement of the disturbance(wave) that maintains its shape(or changes slowly). |
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| The distnace between parts of the wave that repeat themselves. Represented by the Greek letter lambda. |
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| The magnitude of the peak deviation from the average value pf teh disturbance. |
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| Define the parameter called phase. |
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| The angular argument(in degrees or radians)at which the wave begins, as defined by some arbitrary starting point. |
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| What is a positive phase shift referred to as? |
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Definition
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| What is a negative phase shift referred to as? |
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| The number of complete cycles of a periodic wave that pass a stationary point in one second. |
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| What is the propagation of e-m waves in air? |
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| The angle of reflection equals what angle? |
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| Define angle of incidence. |
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Definition
| The angle between the direction of propagation and a line perpendicular to the boundary, on the same side of the surface. |
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| Define angle of reflection. |
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Definition
| The angle between the direction of propagation of the reflective wave and a line perpendicular to the boundary, on the same side of the surface. |
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Definition
| Any pure energy of singular frequency will have the waveform of a sinusoid and is termed coherent energy. |
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| Define noncoherent energy. |
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| Energy that is composed of more than one frequency will NOT have a sinusoidal wave and is considered noncoherent. |
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| What are two advantages of coherent energy? |
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Definition
1)Doppler shift due to moving targets can be measured.
2)Radar receivers with superior signal-to-noise ratios can be used, |
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Term
| What is Maxwell's theory? |
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Definition
| An accelerating electric field will generate a time-varying magnetic field. Conversely, a time-varying magnetic field will generate a time-varying electric field. The result is a traveling wave of electromagnetic energy. |
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Term
| What is the law of reflection or Fresnel's Law? |
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Definition
| The angle of reflection equals the angle of incidence, and the reflected ray lies in the plane of incidence. |
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Term
| What is the line of refraction or Snell's Law state? |
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Definition
| The ratio of the sine of the angle of refraction to the sine of the angle of incidence is constant, and the refracted ray lies in the plane of incidence. |
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Definition
| Diffraction causes plane waves traveling in a straight path to bend around a boundary or obstruction. |
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| What is Maxwell's theory? |
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Definition
| An accelerating electric field will generate a time-varying magnetic field, a time-varying magnetic field will generate a time-varying electric field. |
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Definition
| Process of encoding information |
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| What are the three types of modulation? |
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Definition
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| What are three signal of modulation to be concerned with? |
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Definition
Vinfo(t) - information signal
Vc(t) - carrier signal
VAM(t) amplitude modulated signal |
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Definition
| Very low frequencies and Very long wavelengths - unsuitable for ships & aircraft, except comms |
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1)E-M energy refracts back towards the earth’s surface in upper ionosphere layer.
2)HF Band most effective
3)Wavelengths still too long for anything but comms by aircraft and ships. |
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Definition
1)Above 30 MHz, ionosphere will not refract E-M waves back toward earth.
2)Energy tends to travel in straight line.
3)wave over the geometric and visual horizons to some extent |
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| What are the two basic radar types? |
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Definition
| Pulse Transmission and Continuous Wave |
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