Introduction to Microwave Remote Sensing

Typical radar (RAdio Detection And Ranging) measures the strength and round-trip time of the microwave signals that are emitted by a radar antenna and reflected off a distantsurface or object. The radar antenna alternately transmits and receives pulses at particular microwave wavelengths (in the range 1 cm to 1 m, which corresponds to a frequency range of about 300 MHz to 30 GHz)
and polarizations (waves polarized in a single vertical or horizontal plane).

For an imaging radar system, about 1500 high- power pulses per second are transmitted toward the target or imaging area, with each pulse having a pulse duration (pulse width) of typically 10-50 microseconds (us). The pulse normally covers a smallband of frequencies, centered on the frequency selected for the radar.
Commonly used frequencies and their corresponding wavelengths are specified by a band nomenclature, as follows:

  • Ka Band: Frequncy 40,000-26,000 MHz; Wavelength (0.8-1.1 cm)

  • K Band: 26,500-18,500 MHz; (1.1-1.7 cm)

  • X Band: 12,500-8,000 MHz; (2.4-3.8 cm)

  • C Band: 8,000-4,000 MHz; (3.8-7.5 cm)

  • L Band: 2,000-1,000 MHz; (15.0-30.0 cm)

  • P Band: 1,000- 300 MHz; (30.0-100.0 cm)

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