r = the de resistance provided by the side rails acting as de collecting busses for one single element. If we substitute into this formula the value of n of 13 that is currently being used, and the value of r of 1. 72 x 10“3 ohms for the RXCV rectenna element, we obtain the following expression 2 As an example, if the I R losses represent 1% of the de power collected (k = .01), and w is one watt, the total length of the assembly is 185.4 meters. It follows that the number of elements in the string is 2,405, the de power collected is 2.405 kilowatts and the I^R losses are 24 watts. Depending upon the proper value of resistive load for each rectenna element, there will be between 40 - 60 sections connected in series. Of course, the total number of elements should be some integral multiple of the total number of sections and will, therefore, not be exactly the number 2.405. The weight of the aluminum raw material stock from which the rectenna line loop of 185.4 meters is constructed in 5020 grams or 2.09 grams per element. At a current base price of 41 £ a lb for aluminum, this represents a raw material price of 0. 183 £ per element, or $1.83 per kilowatt. If the size of the rectenna requires 10^ elements, and the construction remains the same throughout the rectenna, a total of 2.3 x 10^ tons of aluminum will be required, or about 0. 35 of one percent of the total aluminum produced in the United States in one year. There is, no doubt, some tradeoff in the value of electrical energy against the investment in conductors for bussing the power. However, the fabrication technique that is shown in Figure 5-3 presents definite restrictions on the cross sectional size of the conductor. It is also noted that rectenna elements made by conventional printed circuit technology would not provide significant self-bussing (or cooling of the diodes) because of the small cross section of the conduction numbers. 5.4 The Design and Construction of the 5-element Foreplane The 5-element foreplane is the terminology used to describe all of the structures shown in Figures 5-2 and 5-3, with the exception of the reflecting plane. This section will describe the design considerations going into the design and construction of the outer metallic shield and the core-assembly.
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