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CLASSICAL PHASED ARRAYS

The classical phased array architecture employs beam steering/forming purely at the RF (IF) level using RF phase and/or amplitude shifters, or beam forming networks. These configurations are used for all frequency bands but are often applied at the X-and Ku-bands. When only a small number of antenna beams need to be generated, a switching network like Butler matrices can be used. When employing a phase shifter per antenna element (or subgroups), MMIC components are normally used. Such compact build-ups have a greater aesthetic appeal, and give them high a good commercial value and thus more market acceptance. However, the greater number of MMIC components has a drastic effect on cost: the size of such an antenna frontend with respect to the number of elements in Ku band, for example, can vary from hundreds to thousands. In the figure below, a receive antenna in Ku- band (linear polarization, 10.7 GHz –12.75 GHz) for automotive applications is displayed. This frontend combines beam pointing and polarization adjustment, and is composed of approximately 150 antenna patches, each equipped with a digitally-controlled phase shifter component.