A phased array is an array of antennas in which the relative phases of the respective signals supplied to the antennas are used to focus the radiation pattern of the array in a desired direction. The signals provided to the array of antennas enable the array of antennas to achieve improved performance over that of a single antenna. The antenna array can, among other things, increase overall gain, receive or transmit a greater diversity of signals, cancel out interference, steer the radiation pattern in a specific direction, or determine the direction of incoming signals. The phase relationship among the antennas can be fixed to form a tower array.
Alternatively, the phase relationship among the antennas can be adjustable to form a beam-steering array. Beam steering allows the direction of the main lobe of a radiation pattern to be changed using constructive and destructive interference between the electromagnetic signals emitted from the various antennas in the array of antennas. This is typically accomplished by switching the antenna elements or by changing the relative phases of the signals (such as RF signals) driving each of the antenna elements.
An example of a beam-steering array is the Advanced Modular Incoherent Scatter Radar (AMISR) by SRI International of Menlo Park, Calif. AMISR has three separate radar faces, with each face including 128 building-block-like panels over a 30- by 30-meter roughly square surface. AMISR is made up of 4,096 antennas, giving a combined power of up to two megawatts. By controlling the relative phases of the signals coming from the individual antennas, the radar beam can be steered almost instantaneously from one position in the sky to another. This allows the study of rapidly moving features of the atmosphere. Remote operation and electronic beam steering allow researchers to operate and position the radar beam to accurately measure rapidly changing space weather events. However, AMISR is roughly the size of a football field.
Phased-array radar systems are also used by the navy in ships as the phased-array radars allow the ships to use a single radar system for surface detection and tracking, finding other ships, and air detection and tracking. Ship-borne phased-array radar systems can use beam steering to track many targets simultaneously while also controlling several in-flight missiles.
Phased-array antenna systems benefits from a large number of radiating elements. The use of more radiating elements enables sharper and narrower beams that provide higher gain. However, as the number of radiating elements increases, the size of the system and the cost of assembly likewise increases, limiting the application of phased-array antenna systems, especially for consumer products. While many applications do exist for phased-array radars, relatively few have been explored since the size and cost of phased-array radars are prohibitive for many applications.
Among other things, as the size of the components shrinks, the difficulty of arranging a plurality of diverse elements increases. Semiconductor chip- or die-automated assembly equipment typically uses vacuum-operated placement heads, such as vacuum grippers or pick-and-place tools, to pick up and apply devices to a substrate. It is often difficult to pick up and place ultra-thin and/or small devices using this technology.
Some electronic devices are difficult to construct by conventional assembly techniques due to their ultra-thin and/or small dimensions. For example, some electronic devices (e.g., micro-integrated circuits) can be less than 0.1 mm in one lateral dimension. Moreover, some electronic devices benefit from a large number of radiating elements (e.g., phased-array radars incorporating more radiating elements can form sharper, narrower beams with higher gain). However, as the number of radiating elements increases, the area needed for the parts and the cost of assembly increases. Furthermore, the spatial distribution of elements such as antennas can result in an inefficient use of area for phased-array antenna systems.
Thus, there is a need for phased-array antenna systems and methods of manufacturing thereof that enable phased-array antenna systems to be packaged into small-scale systems utilizing less semiconductor material than monolithic approaches.
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