![]() ![]() Bragg or resonant scattering is scattering from a regular surface pattern. This can occur if the radar is capable of penetrating deep enough. Even for nonvertical incidence, nevertheless, backscatter can exist for a rough subsurface. Furthermore, the reflected energy is localized to small angular regions around the angle of reflection. This is due to a 90-degree depression angle or the slope of the surface. For the perfect specular reflector, radar returns (backscatter) exist only near vertical incidence. Specular reflection occurs when the water surface is tilted, which creates a small mirror pointing to the radar. Read more Navigate DownĬonsistent with the previously discussed prospective, a backscatter is mainly modeled in two ways: specular reflection and Bragg scattering. Any other method might reduce its performance below that in paragraph 3.3. In the case of an octahedral reflector, the correct method of mounting is one corner cavity at the top and one at the bottom. The reflector should be capable of maintaining its reflection performance under the conditions of sea states, vibration, humidity and change of temperature likely to be experienced in the marine environment.ĥ.1 Fixing arrangements should be provided so that the reflector can be fitted either on a rigid mount or suspended in the rigging.ĥ.2 If there is a preferred orientation of mounting, this should be clearly marked on the reflector. The azimuthal polar diagram should be such that the response over a total angle of 240° is not less than −6 dB with reference to the maxima of the main lobes and that the response should not remain below −6 dB over any single angle of more than 10°. The echoing areas referred to in paragraph 2 correspond to the maximum values of the main lobes of the polar diagram.3 Reflectors should be capable of performance around 360° in azimuth using a typical marine navigational radar.2 If this is not practicable, of at least 40 m 2, mounted at a minimum height of 2 m above water level. Preferably, of at least 10 m 2, mounted at a minimum height of 4 m above water level or. 1.1 Small craft referred to in paragraph 2 of this Recommendation should be fitted with radar reflectors to improve the range and probability of their radar detection.ġ.2 Radar reflectors should comply with the minimum performance requirements as specified in this Recommendation.ġ.3 In the following paragraphs, the echoing areas specified are those for the frequency of 9.3 GHz (corresponding to a wavelength of 3.2 cm).Ģ.1 All ships of less than 100 tons gross tonnage operating in international waters and adjacent coastal areas should, if practicable, be fitted with a radar reflector.Ģ.2 The radar reflector should be of an approved type with an adequate polar diagram in azimuth, and an echoing area.
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