ls. The logic of how to control The RF front-end consists of the receiver and the the pointing depends greatly on the application. Examples transmitter analog functions. The receiver and trans- include: (1) exchanging the global positioning system mitter generally consist of frequency up converters and (GPS) position of each transceiver in the network, as well down converters, filters, and amplifiers. Sophisticated as tracking the three-dimensional (3-D) orientation of the radios will choose filters and frequency conversions that platform on which the antenna is mounted SO that the minimize spurious signals, images, and interference antenna pointing vector to any network member can be within the frequency range over which the radio must calculated; (2) scanning the antenna full circle to find the work. The front-end design will also maximize the dy- maximum signal strength; (3) dithering the antenna while namic range of signals that the receiver can process, tracking peak performance; or (4) using multiple receive through automatic gain control (AGC). For a tactical feed elements and comparing their relative strength. defense application radio, it is common to be able to Another common antenna is the electronically steered continuously tune from 2 MHz to 2 GHz, and to support antenna. Control interfaces to these antennas are quite analog signal bandwidths ranging from 25 kHz to 30 MHz. similar in function; however, due to the ability to rapidly Commercial applications need a much smaller tuning steer electronically, many of these antennas update their range. For example, a cell phone subscriber unit might steering angle as rapidly as once every millisecond. Thus, tune only 824 MHz-894 MHz and might need only one response time of the control interfaces is critical to the signal bandwidth. With a simplified design, the designer expected function. can eliminate many filters, frequency conversions, and IF The most sophisticated antenna is the multiple input, bandwidth filters, with practical assumptions. multiple out