| Cover |
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| Title Page |
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| Report Metadata |
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| Table of Contents |
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| List of Illustrations |
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| Figure 1-1. First experiment in the efficient transfer of power by means of microwaves |
21 |
| Figure 1-2. Microwave powered helicopter in flight 18. 28 meters above a transmitting antenna |
22 |
| Figure 1-3. The first rectenna. Conceived at Raytheon Company |
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| Figure 1-4. The special rectenna made for the first microwave-powered helicopter. |
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| Figure 1-5. Greatly improved rectenna made from improved diodes (HP2900) which are commercially available. |
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| Figure 1-6. Test set-up of microwave power transmission system at Marshall Space Flight Center in 1970 |
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| Figure 1-7. Close-up view of first rectenna developed by Raytheon under MSFC contract |
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| Figure 1-8. Experimental set-up comprised of dual-mode horn and improved rectenn |
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| Figure 1-9. Sketch of the Marshall Space Flight Center rectenna which was constructed in spring of 1974 |
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| Figure 1-10. Photograph of the MSFC rectenna constructed in 1974 under test. |
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| Figure 1-11. Simplified Electrical Schematic for the rectenna element used in the RXCV receiving array at the Venus site of the JPL Goldstone facility |
34 |
| Figure 1-12. Photograph of rectenna element designed for JPL RXCV demonstration at Goldstone |
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| Figure 1-13. Photograph of the microwave power transmission system at the Raytheon Co. in which a certified overall DC to DC efficiency of 54% was obtained in March 1975 |
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| Figure 1-14. Distribution of system and subsystem efficiencies (measured and estimated) in the experiment to obtain a certified measurement |
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| Figure 1-15. Photo of the 24. 5 Square Meter Rectenna at the Venus Site of the Goldstone Facility of the Jet Propulsion Laboratory. |
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| Figure 1-16. Progress in rectenna element efficiency as a function of time |
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| Figure 2-1. The Rectenna Element Test Arrangement Utilizing the Expanded Waveguide Test Fixture. |
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| Figure 2-2. The Rectenna Element Test Arrangement Utilizing the Test Fixture with RF Ground Plane |
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| Figure 2-3. Close-up View of the "Split" Rectenna Element Mounted on the Ground-Plane Test Fixture. |
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| Figure 2-4. Diagram of the Arrangement for Measuring Diode Losses |
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| Figure 2-5. View of the Back Side of the Ground-Plane Test Fixture |
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| Figure 2-6. Schematic Arrangement of Test Equipment for Calibration of Incident Microwave Power |
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| Figure 2-7. Typical Calibration Curve |
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| Figure 2-8. Zero Drift on Thermistor Bridge |
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| Figure 2-9. Transient Response of Thermistor Bridge to step function of DC Power Input |
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| Figure 2-10. The DC power output, losses in the microwave diode, and losses in the input filter circuit |
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| Figure 2-11. Simplified Math-Model Schematic Diagram for Interpreting Computer-simulation |
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| Figure 2-12. Time Behavior of Input Current to Rectenna Element |
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| Figure 2-13<Time Behavior of Input Voltage to Rectenna Element |
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| Figure 2-14. Comparison of Computer Simulation Computations of Efficiency, Diode Losses, and Circuit Losses with those obtained experimentally |
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| Figure 3-1. A summary of the efficiencies achieved with various new rectenna and diode configurations |
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| Figure 3-2. Rectenna Element Test Vehicle |
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| Figure 3-3. RXCV Rectenna Element modified to provide higher characteristic impedance |
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| Figure 3-4. Expanded waveguide section modified to permit testing of rectenna element |
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| Figure 4-1. Comparison Between Voltage Current Chara |
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| Figure 4-2. Diode Matrix and Manufacturing Sequence |
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| Figure 4-3. Diode Life Test Results |
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| Figure 5-1. Proposed design of Rectenna motivated by environmental protection and cost considerations. |
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| Figure 5-2. Physical construction of two-plane rectenna |
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| Figure 5-3. Basic core structure design illustrating the joining of individual rectenna elements |
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| Figure 5-4. Proposed method of continuous fabrication of the core assembly of rectenna elements. |
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| Figure 5-5. A mechanical mockup of the proposed design of Figure 5-1 |
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| Figure 5-6. Artists' concept of a moving rectenna factory. Materials brought in at one end of factory are basic ingredients to high speed automated manufacture and assembly of rectenna panels |
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| Figure 5-7. Suggested assembly method in which staked-in ceramic pins provide the dual function of assembling the rectenna element and behaving |
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| Figure 5-8. Schematic electrical drawing showing how the sections of parallel diodes are connected in series to build up to the desired voltage level |
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| Figure 5-9. Fabricated Metal Shield Halves Which Will Support and Shield, Both Electrically and Environmentally |
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| Figure 5-10. Completed rectenna fore-plane assembly |
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| Figure 5-11. Input admittance to the foreplane rectenna element measured at the junction of the half-wave dipole to the low-pass filter section. |
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| Figure 5-12. The test set-up for checking the foreplane type of rectenna array. |
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| Figure 5-13. Schematic Showing that all Rectenna Elements are Parts of Sets |
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| Figure 5-14. The average DC power output per element in a set of elements is plotted |
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| Figure 5-15. Experimentally observed power output of the 5-element foreplane structure is compared with predicted power |
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| Figure 5-16. The power output of the foreplane structure and other sets of rectenna elements |
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| Figure 5-17. Agreement between experimentally measured DC power from the foreplane structure and predicted value |
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| Figure 5-18. VSWR ratio and min position as a function of the DC load resistance of the foreplane |
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| Figure 5-19. Rectenna Edge to Horn Mouth Spacing 67 Inches |
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| Figure 7-1. Sketch of Recommended System |
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| Summary |
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| 1.0 Introduction |
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| 1.1 Description of free-space power transmission by microwave beam and its early development |
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| 1.2 Major Microwave Collector-Converter Technology Developments |
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| 1.3 Progress in Rectenna Efficiency Using Progress in Rectenna Element Efficiency as an Index |
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| 1.4 The Energy Problem and the Solar Power Satellite Concept as Factors in Determining the Extent and Direction of Rectenna Development |
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| 1.5 Objectives of the Technology Development Reported Upon in this Report |
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| 2.0 Improvement in techniques for measuring the efficiency and losses of rectenna elements |
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| 2.1 Introduction |
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| 2.2 Techniques for Measuring the Efficiency and Losses of Rectenna Elements |
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| 2. 2. 1 Measurement Equipment |
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| 2.2. 2 Calibration of Microwave Power Input |
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| 2. 2. 3 Measurement of Diode Losses |
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| 2.2.4 A Check on Measurement Accuracies by Balancing Measurements of Input Microwave Power Against the Sum of the Measurements of DC Power Output, Diode Losses, and Circuit Losses |
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| 2.3 The Development of a Mathematical Model of the Rectenna Element Together with Computer Simulation Program and its Use |
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| 2.3.1 Introduction |
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| 2.3.2 Mathematical Model of the Rectenna Element |
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| 2. 3.3 A Representative Set of Data Resulting from the Use of theComputer Simulation Program |
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| 2.4 Agreement of Computer Simulation Data with Experimental Measurements. |
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| 2.4.1 Comparison of Simulated Efficiency and Losses with Those Measured Experimentally |
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| 3.0 Rectenna element circuit modifications |
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| 3.1 Introduction |
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| 3. 2 Circuit Modifications to permit more efficient operation at reduced MW power input levels. |
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| 3.2.1 Introduction and summary of results |
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| 3.2.2 The Design and Construction of Circuits for more efficient operation at lower power levels |
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| 3.2.3 Other Approaches to Efficient Operation at Lower Power Levels |
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| 3.3 Initial Effort in Integration of Rectenna Element into a Two Plane Structure |
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| 3.4 The Reduction of Second and Third Harmonic Radiation with the use of Stub Lines |
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| 3.5 Reduction in radiated harmonic power by metallic shielding |
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| 3.6 Improvement in the efficiency and in the consistency of efficiency measurements by refinements in the construction of the RXCV rec- tenna element. |
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| 4.0 Schottky Barrier diode development |
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| 4.1 The Diode Design and Construction Matrix |
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| 4.2 Life Test on Rectenna Elements and Diodes |
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| 5.0 The longe range objective: SPS/SSPS DEPLOYMENT, Integration of improved diodes and circuits into a design compatible with |
91 |
| 5.1 Introduction |
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| 5.2 Outline of a Production Process for the SSPS Rectenna |
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| 5.3 Interrelationships Between the Losses in DC Bussing, the Cross Section of the DC Busses, the DC Power Collected by Each Element, the Density of the Rectenna Elements, and the Required DC Output Voltage Level |
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| 5.4 The Design and Construction of the 5-element Foreplane |
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| 5.4.1 Considerations in the Design of the Outer Metallic Shield |
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| 5.4.2 Considerations in the Design of the Core Assembly |
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| 5.5 Tests of the Separate Rectenna Elements in the Foreplane Structure with the use of the Expanded Waveguide Fixture |
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| 5.6 Smith Chart Presentation of Reflection Data |
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| 5.7 Test of the 5-element Foreplane as an Integrated Part of a Larger Array |
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| 6.0 Summary of Results |
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| 7.0 Concluding remarks and recommendations |
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| APPENDIX A: Development of a computer simulation program for the RXCV rectenna element |
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| APPENDIX B: References |
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