5-10 Completed rectenna fore-plane assembly consisting of metallic shield and the core assembly of five rectenna elements. 86 5-11 Input admittance to the foreplane rectenna element measured at the junction of the half-wave dipole to the low- pass filter section. Input admittance is a function of the input microwave power level and the DC load resistance. Data were obtained using the expanded waveguide test fixture and one of the elements in the foreplane construction. The rectenna element tested was connected in the intended manner to the adjacent rectenna elements. The susceptance component can be varied by resetting the position of the movable short near the diode rectifier. By adjusting this setting and the DC load, it is possible to obtain a zero power reflection for a wide range of incident power. The 5-watt input level was placed at the center of the Smith Chart because this is the intended power level of operation when the foreplane structure is put into the 199- element rectenna for test. 91 5-12 The test set-up for checking the foreplane type of rectenna array. The five element foreplane structure is placed at the center of the array as shown. The DC output is dissipated in a resistive load. The collected power from the foreplane can then be compared with the power that would have been collected from the five elements that it replaced by a procedure discussed in the text. 93 5-13 Schematic Showing that all Rectenna Elements are Parts of Sets with Six or Twelve Elements Per Set, which lie on Circles Concentric with the Rectenna Center. In the 199-Element Array there are 7 additional sets to the 14 of this figure. 95 5-14 The average DC power output per element in a set of elements is plotted as a function of the radial distance of the set. The resulting points of data may be easily fitted to a Gaussian curve which is the approximate power density distribution in the beam. 96 5-15 Experimentally observed power output of the 5-element fore-plane structure is compared with predicted power based upon power picked up by remaining elements in sets whose total number of elements included elements in the foreplane structure. Data set Not 1 and No. 2 were taken at different times. Inconsistency of data at the "relative incident microwave power" value of 1.0 is caused by difficulty in resetting the incident microwave power level from one set of measurements to another. 96
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