dB below the fundamental carrier. Furthermore, the magnetron warm-up time is only 2 to 3 seconds before CW operations can begin. Once the energy has been converted to the desired frequency, it can be transformed into a "beam" for transmission to the relay satellite reflector. This is accomplished with a transmitting or a phased array antenna. A phased-array antenna is comprised of a large number of smaller antenna elements which are controlled so that each element's beam will constructively combine to produce a beam with the same characteristics as that of a single-dish antenna. This beam can then be steered electronically, by controlling the phase of each element's output. A phased-array antenna can be used with a single high-power microwave generator by dividing the power output of the generator into the different radiating elements, and then recombining the power by controlling the individual radiators. However, it may be advantageous to use many, smaller microwave generators which will feed the radiating elements directly, and form part of an active phased array. Control must be exercised over the microwave generators as well as the radiating elements to ensure that the transmitted beam will conform to system requirements. With this configuration, the reliability of the transmitter will be high as there will not be a single point of failure. The configuration of the active phased-array design features graceful degradation as large number of sub-elements could fail without causing the system to be shut down. A magnetron microwave module can be replicated and combined with a slotted wave guide antenna assembly into a large transmitter structure. Rectenna The role of the rectenna is to transform the incoming microwave beam energy into a format suitable for interfacing with the distribution grid. The received microwave energy is converted into de using a rectification process. In an efficient rectenna, the reception and rectification functions are combined into a single device, a dipole rectifier. The dipole-type antenna is used for its omni-directional features, i.e. the efficiency of its reception is not strongly dependent upon the angle of incidence of the microwave beam. The rectification function is accomplished with a solid state diode. The parameters of the diode's design can be optimized for high efficiency, using gallium arsenide as the material of choice for the diode. Other functions are designed into the rectenna, such as de filtering to purify the output voltage, and RF filtering to limit the amount of reradiation from the diodes through the dipoles. The receiver is comprised of many thousands of rectenna elements. The de output of each rectenna element is combined with the others to produce a high power output from the rectenna system. The high power is conditioned and properly formatted for its intended use with standard power conditioning equipment. Reflector The design of the PRS must be both functional and practical. A frequency selective surface can be used to design a reflector structure that is highly reflective at the desired frequency, 2.45 or 5.8 GHz, and transparent at frequencies outside of the chosen frequency. A frequency selective surface allows the deployment of a PRS with minimum
RkJQdWJsaXNoZXIy MTU5NjU0Mg==