Military sonars often have multiple beams to provide all-round cover while simple ones only cover a narrow arc, although the beam may be rotated, relatively slowly, by mechanical scanning.
12.
Luminance, contrast and chromaticity of viewing direction can be measured sequentially by mechanical scanning of the viewing cone ( " gonioscopic " approach ) or by simultaneous measurements based on conoscopy.
13.
Azimuth was determined by mechanical scanning while the angle of the target is determined from within which beam of the antenna stack the target is detected, the radar does not carry a secondary antenna for IFF.
14.
In working on the Microwave Early Warning system ( MEW ), Alvarez invented a linear dipole array antenna that not only suppressed the unwanted side lobes of the radiation field, but also could be electronically scanned without the need for mechanical scanning.
15.
Rotating drums bearing small mirrors set at progressively greater angles proved more practical than Nipkow discs for high-resolution mechanical scanning, allowing images of 240 lines and more to be produced, but such delicate, high-precision optical components were not commercially practical for home receivers.
16.
Even as early as 1908, it was recognised that " The final, insurmountable problems with any form of mechanical scanning were the limited number of scans per second, which produced a flickering image, and the relatively large size of each hole in the disk, which resulted in poor resolution ".
17.
Replacing a mechanically scanned array with a fixed AESA mount ( such as on the Boeing F / A-18E / F Super Hornet ) can help reduce an aircraft's overall radar cross-section ( RCS ), but some designs ( such as the Eurofighter Typhoon ) forgo this advantage in order to combine mechanical scanning with electronic scanning and provide a wider angle of total coverage.
