The equiangular spiral antenna
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A circularly polarized antenna is described which makes possible bandwidths that a few years ago were considered to be impossible and an essentially constant radiation pattern and input impedance over bandwidths greater than 20 to 1.Abstract:
A circularly polarized antenna is described which makes possible bandwidths that a few years ago were considered to be impossible. The design of the antenna is based upon the simple fundamental principle that if the shape of the antenna were such that it could be specified entirely by angles, its performance would be independent of wavelength. Since all such shapes extend to infinity it is necessary to specify at least one length for an antenna of finite size. The one length in this antenna, the arm length, need only be of the order of one wavelength at the lowest frequency of operation to obtain operation essentially independent of frequency, and the geometry of the antenna allows this arm length to be spiraled into a maximum diameter of one half wavelength or less. Antennas have been constructed that have an essentially constant radiation pattern and input impedance over bandwidths greater than 20 to 1.read more
Citations
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Journal ArticleDOI
Gold Helix Photonic Metamaterial as Broadband Circular Polarizer
Justyna K. Gansel,Michael Thiel,Michael S. Rill,Manuel Decker,Klaus Bade,Volker Saile,Georg von Freymann,Stefan Linden,Martin Wegener +8 more
TL;DR: This work investigated propagation of light through a uniaxial photonic metamaterial composed of three-dimensional gold helices arranged on a two-dimensional square lattice that is scalable to other frequency ranges and can be used as a compact broadband circular polarizer.
Book
Frequency independent antennas
TL;DR: In this article, it was shown that the pattern converges to the characteristic pattern as the frequency is raised, if a is not \infty, and that the impedance converges with the characteristic impedance for all a, assuming a to be positive, \varpi ranges from - ∞ to some finite value which determines the low frequency limit.
Journal ArticleDOI
Tunable, continuous-wave Terahertz photomixer sources and applications
Sascha Preu,Sascha Preu,Gottfried H. Döhler,Stefan Malzer,Longze Wang,Longze Wang,Arthur C. Gossard +6 more
TL;DR: In this article, the authors present various realizations of both photoconductive and p-i-n diode-based photomixers to overcome the limitations of operation at high frequencies, namely transit time or lifetime rolloff, antenna (R)-device (C) RC roll-off, current screening and blocking and heat dissipation.
Journal ArticleDOI
Millimeter-wave and terahertz integrated circuit antennas
TL;DR: A comprehensive review of integrated circuit antennas suitable for millimeter and terahertz applications is presented in this paper, where several antennas, such as the integrated horn antenna, the dielectric-filled parabola, the Fresnel plate antenna, dual-slot antenna, and the log-periodic and spiral antennas on extended hemispherical lenses, which have resulted in excellent performance at millimeter-wave frequencies, are covered in detail.
Journal ArticleDOI
Fractal multiband antenna based on the Sierpinski gasket
TL;DR: In this article, the self-similarity properties of the Sierpinski antenna's fractal shape is exploited for designing new multiband and frequency independent antennas, based on which a multiband behavior over five bands is demonstrated.
References
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Book
Frequency independent antennas
TL;DR: In this article, it was shown that the pattern converges to the characteristic pattern as the frequency is raised, if a is not \infty, and that the impedance converges with the characteristic impedance for all a, assuming a to be positive, \varpi ranges from - ∞ to some finite value which determines the low frequency limit.
Proceedings ArticleDOI
Broadband logarithmically periodic antenna structures
R. DuHamel,D. Isbell +1 more
TL;DR: Antenna structures for which the input impedance and radiation patterns vary periodically with the logarithm of the frequency are described, the result being an antenna forwhich the impedance and patterns are essentially independent of frequency over bandwidths greater than ten to one.
Journal ArticleDOI
Radiation Field of a Conical Helix
TL;DR: In this paper, it was shown that if the helix was conical instead of cylindrical (the diameter varying along the length of helix), then the axial mode of radiation can be maintained over a much wider band of frequencies.