BASIC RADAR CONFIGURATION

be short enough to detect fine scatterers without sacrificing severe weather detection abilities. Amplitude Wave amplitude is simply the wave’s height (from the midline position) and represents the amount of energy or power contained within the wave. Simply put, greater amplitude means more power. Amplitude is usually expressed as some fraction of a meter (fig. 2-5). Frequency Frequency refers to the number of completed wave cycles per second. Radar frequency is expressed in units of hertz (Hz); one hertz being equal to one cycle per second. Frequency and wavelength are closely related as a change in one has a direct impact on the other. Essentially, higher frequency transmitters produce shorter wavelengths and lower frequency transmitters produce longer wavelengths. All wave characteristics in some way affect radar power. When more energy is available to strike targets, both signal strength and data reliability are increased and the radar performs more efficiently. Electromagnetic waves can be described in terms of either frequency or wavelength. Looking back at figure 2-2, you can see the function of frequency versus wavelength. Power Power is the rate at which energy is used, With electromagnetic energy, the decibel system is used to compare two power values. A decibel, abbreviated "dB” is one tenth of a bel, the fundamental unit. The decibel system is useful for comparing power values that differ greatly, such as transmitter and receiver power. Values for dB are measured logarithmically, not linearly. With this in mind, you must be aware that every change of 3 dB corresponds to a doubling (or halving) of power. Doppler reflectivity values, which will be discussed later, are indicated by the abbreviation "dBZ." Q1. Q2. Q3. Q4. Q5. Q6. Q7. REVIEW QUESTIONS What is an electromagnetic wave? Radar energy occupies what portion of the electromagnetic spectrum? Wavelength is usually measured in what units? How does wavelength affect a radar’s ability to detect different types of targets? Define radar frequency. Given a frequency of 200 MHz and a frequency of 100 GHz, which one has a shorter wavelength? How can different radar power values be compared? BASIC RADAR CONFIGURATION LEARNING OBJECTIVES: Define reflectivity. Identify the major parts of a radar system. Define radar sensitivity. The acronym RADAR stands for RAdio Detection And Ranging. Radio waves, like light waves, are reflected from objects. The term reflectivity refers to the amount of energy returned from an object and is dependent on the size, shape, and composition of the Figure 2-5.—Amplitude of an electromagnetic wave. 2-4