In this work, we designed, built, and tested a low-gain 20 dBi Luneburg Lens antenna using a rapid prototyping machine as a proof of concept demonstrator. The required continuously varying relative permittivity profile was implemented by changing the size of plastic blocks centered on the junctions of a plastic rod space frame. A 12-cm ( 4λ0 at 10 GHz) diameter lens is designed to work at X-band. The effective permittivity of the unit cell is calculated by effective medium theory and simulated by full-wave finite-element simulations. The fabrication is implemented by a polymer jetting rapid prototyping method. In the measurement, the lens antenna is fed by an X-band waveguide. The measured gain of the antenna at X-band is from 17.3 to 20.3 dB. The measured half-power beam width is from 19° to 12.7° while the side lobes are about 25 dB below the main peak. Good agreement between simulation and experimental results is obtained.

A 3-D Luneburg Lens Antenna Fabricated by Polymer Jetting Rapid Prototyping

The flexibility of modern monopulse radar antenna systems makes possible the independent optimization of sum and difference patterns. The two parameter difference pattern, developed here for the circular aperature antenna, is designed to have nearly equal sidelobes similar to those of the Taylor sum pattern. The difference pattern is asymptotic to a model difference pattern which has the greatest slope (angle sensitivity) for a given sidelobe level. The model function is unrealizable because it has uniform sidelobes which are infinite in extent. The two parameter difference pattern is realizable and is expressed in a Fourier — Bessel series of N terms in a manner similar to Taylor's treatment of the sum pattern. The other parameter, A, controls sidelobe level. Comprehensive tables of the Fourier — Bessel coefficients are given for both the circular aperture series and the difference pattern series. Directivity and angle sensitivity are investigated and found to have maximum values that decrease as sidelobe level decreases. The monopulse system performance using the asymptotic difference pattern and the Taylor sum pattern compares favorably with a maximum likelihood angle estimation system. Development of a line source difference pattern is presented in the appendix.

Design of monopulse antenna difference patterns with low sidelobes

Preface. Acknowledgments. Chapter 1 Introduction. 1.1 Prologue. 1.2 Development of Magnetism. 1.3 Development of Electricity. 1.4 Development of the Theory of Light. 1.5 Who Was Maxwell? 1.6 What WasAs Maxwell's Electromagnetic Theory? 1.7 Conclusions. Chapter 2 A Chronology of Developments of Wireless Communication and Supporting Electronics. 2.1 Introduction. 2.2 Acknowledgments. 2.3 Background. 2.4 Some Crucial Events of the Nineteenth Century. 2.5 Some Crucial Events of the Twentieth Century. 2.6 Epilogue. Chapter 3 Evolution of Electromagnetics in the Nineteenth Century. 3.1 Introduction. 3.2 Continental Electromagnetics. 3.3 British Electromagnetics. 3.4 Conclusion. Chapter 4 The Genesis of Maxwell's Equations. 4.1 Introduction . 4.2 On Faraday's Lines of Force. 4.3 On Physical Lines of Force. 4.4 A Dynarnical Theory of the Electromagnetic Field . Chapter 5 Maxwell, Hertz, the Maxwellians and the Early History of Electromagnetic Waves. 5.1 Introduction. 5.2 Speculations of Electromagnetic Propagation Before Maxwell. 5.3 Maxwell's Electromagnetic Theory of Light. 5.4 Acceptance of Maxwell's Theory. 5.5 Hertz and the Maxwellians. 5.6 Conclusion. Chapter 6 Oliver Heaviside. 6.1 Introduction. 6.2 Heaviside's Life. 6.3 Heaviside's Contributions. 6.4 Conclusions. 6.5 Acknowledgments. Chapter 7 Wireless before Marconi. 7.1 Introduction. 7.2 Conduction Telegraph. 7.3 Induction Telegraph . 7.4 Electromagnetic Telegraph. Chapter 8 Nikola Tesla and His Contributions to Radio Development. 8.1 Introduction. 8.2 Invention of the Tesla Coil. 8.3 Radio Controlled Vehicle. 8.4 Colorado Springs Laboratory. 8.5 Marconi and Braun Research. 8.6 Long Island Laboratory. 8.7 Conclusions. 8.8 Acknowledgments. Chapter 9 An Appreciation of J. C. Bose's Pioneering Work in Millimeter and Microwaves. 9.1 Introduction. 9.2 Historical Perspective. 9.3 A 60 GHz Transmission System. 9.4 Development of the Receiver. 9.5 Demonstration of Propagation. 9.6 Demonstration of the Phenomenon of Refraction. 9.7 Demonstration of the Phenomenon of Polarization. 9.8 Demonstration of the Phenomenon Similar to Photoelectric Effect. 9.9 Measurement of Wavelength. 9.10 Development of the Galena Detector. 9.1 1 Biological Effects of millimeter Waves. 9.12 Conclusion 9.1 3 Epilogue. 9.14 Biographical Sketch. . Chapter 10 Sir John Ambrose Fleming - His Involvement in the Development of Wireless. 10.1 Introduction. 10.2 The Early Years. 10.3 Research of the University Professor. 10.4 Scientific Advisor to the Marconi Company. 10.5 The Thermionic Valve. 10.6 Later Life. Chapter 11 Historical German Contributions to Physics and Applications of Electromagnetic Oscillations and Waves. 11.1 Introduction. 1 1.2 Chronology of Historical German Contributions. 11.3 Acknowledgments. Chapter 12 The Development of Wireless Telegraphy and Telephony, and Pioneering Attempts to Achieve Transatlantic Wireless Communications. 12.1 Introduction. 12.2 A Brief History of the Birth of Wireless. 12.3 Experiments on Sparks and the Generation of Electromagnetic Waves. 12.4 Early Receiving Device. 12.5 Continuous Wave Transmitters. 12.6 Antenna Systems. 12.7 Marconi's First Transatlantic Experiment . 12.8 Marconi's Stations at Glace Bay. 12.9 Fessenden's Brant Rock Station. . 12.10 Transatlantic Experiments in the First Decade of the Twentieth Century. 12.11 On Qualitykeliability of Marconi's Transmission. 12.12 On Qualitykeliability of Fessenden's Transmission. 12.13 Marine Wireless Communications. 12.14 Wireless Telephony Is Born. 12.15 The First Radio Propagation Experiments. 12.16 Fessenden and Marconi, the Men. 12.1 7 Closing Remarks. 12.18 Acknowledgements. Chapter 13 Wireless Telegraphy in South Africa at the Turn of the Twentieth Century. 13.1 Introduction. 1 3.2 The Cape Colony. 13.3 The South Ahcan Republic. 13.4 The British Experience. 13.5 After the South African War. 13.6 IEEE Milestone in Electrical Engineering. 13.7 Acknowledgments. Chapter 14 The Antenna Development in Japan: Past and Present. 14.1 Introduction. 14.2 Maxwell, Hertz, and Their Followers in Japan. 14.3 Marconi and the First Japanese Wireless Communication. 14.4 Sea Battle of the Tsushima Straits and the Japanese Radiotelegraph . 14.5 Yagi-Uda Antenna. 14.6 Kinjiro Okabe and his Split-Anode Magnetron. 14.7 Radar in World War II. 14.8 Electrical Engineering Milestones in Japan. 14.9 Conclusion. Chapter 15 Historical Background and Development of Soviet Quasioptics at Near-mm and Sub-mm Wavelengths. 15.1 Introduction. 15.2 Quasioptics in the Broad and Narrow Sense. 15.3 Pioneering Research into "Hertz Optics" (1 888-1 900) and Lebedev's Contribution. 15.4 Early Success: Free Space Gaussin-Beam Quasioptical Technologies. 15.5 Alternative: Metallic Oversized Waveguides (since 1953) - Quasioptics in Disguise. 15.6 Compromise No 1 : Discrete Beam Waveguides and East-West Competition (since 1961). 15.7 Compromise No. 2: Continuous Beam Waveguides as a Widely Used USSR Technology (since 1963). 15.8 Brief Survey of Modeling Methods and Tools Used in Quasioptics. 15.9 New Frontiers of the XXI Century: Optics Goes Quasioptical. 15.10 Acknowledgments. Chapter 16 The Evolution of Electromagnetic Waveguides: From Hollow Metallic Guides to Microwave Integrated Circuits. 16.1 Hollow Metallic Waveguides. Chapter 17 A History of Phased Array Antennas. 17.1 Introduction. 17.2 The Early History. 17.3 Electromechanical and Frequency Scanning. 17.4 The Technology of Array Control. 17.5 Phase Array Analysis and Synthesis. 17.6 The Future. 17.7 Author's Comments. 17.8 Acknowledgments. References. Index.

History of Wireless

The thesis describes a method of' beam steering aimed at
producing a useful amount of deflection of an antenna beam
from boresight, by a simple and Inexpensive method. For
large antennas, It is difficult, as well as expensive, to
steer the beam by more than a few beamwidths. The method
studied was developed with particular reference to the
beam steering requirements of Direct Broadcast Satellite
flat plate antennas.
The method involves two dielectric wedges, having circular
faces, placed In front of the antenna. By adjusting the
relative angular position of the wedges, the beam can be
steered In any direction, up to a maximum value from the
antenna boresight direction. The maximum value of the
deflection is determined by the wedge angle and the
dielectric constant of the wedge material. This method of
beam steering Is Independent of frequency. Frequency
limitations are, however, set by the need for a matching
layer on the wedge faces to reduce the loss due to
reflection and also due to interference of multiple
reflection effects on the radiation pattern.
Extensive investigations are made (both theoretical and
experimental) to predict the performance of the wedges as
the beam Is steered. The effect of reflection is studied and a new matching technique is devised. Other practical
considerations for example, stepping the wedges for weight
reduction, the effect of loss in the dielectric material
and cross polar performance are also taken into account.
Some effort is given to explore the possibility of using
metal loaded artificial dielectrics using polyurethane as
the base material.
Finally, a number of charts are presented to determine the
amount of beam steering for an arbitrary position of the
wedges.

A beam steering technique using dielectric wedges

In this article, the size of antenna Fresnel and Fraunhofer field regions are systematically derived starting from a general phase factor representation of the scalar diffraction theory. This is done by first expressing the phase of an arbitrary aperture field in a Taylor series in terms of a small parameter and then by subsequently imposing appropriate conditions for the Fresnel and Fraunhofer regions.

L.C. Van Atta

Papers

Microwave scanning antennas, vol l, apertures