1-15 Photo of the 264 Square Foot Rectenna at the Venus Site of the Goldstone Facility of the Jet Propulsion Laboratory. Power was transferred by microwave beam over a distance of one mile and converted into over 3 0 kW of cw power which was dissipated in lamp and resistive load. Of the microwave power impinging upon the rectenna, over 82% was converted into de power. The rectenna consisted of 17 subarrays, each of which was instrumented separately for efficiency and power output measurements. Each rectenna housed 270 rectenna elements, each consisting of a half-way dipole, an input filter section, and a Schottky-barrier diode rectifier and rectification circuit. The de outputs of the rectenna elements were combined in a series-parallel arrangement that produced up to 200 volts across the output load. Each subarray was protected by means of a selfresetting crowbar in the event of excessive incident power or load malfunction. Each diode was self-fused to clear it from short-circuiting the array in the event of a diode failure. 21 1-16 Progress in rectenna element efficiency as a function of time. 23 2-1 The Rectenna Element Test Arrangement Utilizing the Expanded Waveguide Test Fixture. 2-2 The Rectenna Element Test Arrangement Utilizing the Test Fixture with RF Ground Plane. Also shown is added directional coupler and HP analyzer to measure harmonic power level. 28 2-3 Close-up View of the "Split" Rectenna Element Mounted on the Ground-Plane Test Fixture 29 2-4 Diagram of the Arrangement for Measuring Diode Losses 29 2-5 View of the Back Side of the Ground-Plane Test Fixture Showing the Mounting of the Two Thermistors Which are Used in a Bridge to Measure the Diode Losses. The Thermistors Measure the Temperature Drop Across the Heat Flow Path from the Diode Heat Sink to the large Heat Sink of the Heavy Brass Plate. 3 0 2-6 Schematic Arrangement of Test Equipment for Calibration of Incident Microwave Power at the Input to the Rectenna Element Test Fixture 3 2
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