The surface-wave aerial
01 Sep 1960-Vol. 107, Iss: 12, pp 202-212
TL;DR: In this article, it is shown that a dielectric-coated cylinder which is approximately a wavelength in circumference can act as a waveguide for higher-order surface waves, of which the first order is an example.
Abstract: The radiation from the open-circuited end of an externally dielectriccoated metallic waveguide can be controlled by varying the size of the guide, the thickness and/or the dielectric constant of the coating. A new type of aerial designed around this principle is given the name `surface-wave aerial' and radiation-pattern measurements are used to confirm the theory underlying this type of radiator. According to its mode of operation it belongs to the category of end-fire aerials, which are briefly reviewed to show that surface-wave aerials occupy a place in their own right amongst the many possible arrangements that utilize the end-fire effect to produce a directional radiation pattern. The theory of the surface-wave aerial is developed in detail, a necessary preliminary step being a full theoretical analysis of the properties of the first-order cylindrical surface wave. It is shown that a dielectric-coated cylinder which is approximately a wavelength in circumference can act as a waveguide for higher-order surface waves, of which the first order is an example. The `characteristic equation' is determined for the general case from which the cut-off frequency, propagation coefficient and conditions under which propagation can take place are derived in turn. Two specific cases are evaluated numerically and the results are used to calculate the polar diagrams of surface-wave aerials operating at 9Gc/s. The wavelength constant as well as the continuous radiation loss of a surface waveguide for which λg/λ0≃1 are measured directly and the results obtained are used to account for the radiation pattern of very long aerials. In conclusion, an outline of future work is given.
Citations
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01 Sep 1978
TL;DR: In this article, a comprehensive analysis of the electrically small material-clad monopole is performed by representing the various fields by discrete and continuous eigenvalue spectrums, and the antenna radiation pattern, bandwidth, efficiency and input impedance as a function of electrical size and frequency.
Abstract: A comprehensive analysis of the electrically-small material-clad monopole is performed by representing the various fields by discrete and continuous eigenvalue spectrums. The cladding creates a dominant quarter-wavelength resonant-cavity effect whereby the leakage of radiation at the terminal plane is transformed into a low impedance at the annular feed. The mode coupling taking place at both feed and terminal plane is solved by variational methods to yield the antenna radiation pattern, bandwidth, efficiency and input impedance as a function of electrical size and frequency. The agreement between the computed and measured results establishes the usefulness of the analysis, and design curves are presented; other factors that influence the system performance of the antennas in practice are discussed. It is concluded that the optimisation of this type of antenna centres on the choice of suitable low-loss material with comparable relative permeability and permittivity values at the frequency of interest. In general, this calls for research into improved materials, but useful antennas can be made with commercially available materials.
47 citations
01 Mar 1967
TL;DR: In this article, a detailed application of the vector Kirchhoff formula to uniform cylindrical dielectric rods supporting the HE11 mode produces an expression for the far-field radiation pattern, which, when computed, gives good agreement with existing experimental data.
Abstract: Present-day theory of uniform cylindrical dielectric-rod antennas rests on the three theoretical treatments of Horton, Bouix and Fradin (leaky-guide theory), and on Brown's end-fire theory A digression on the general relationship between Schelkunoff's equivalence principle and the vector Kirchhoff formula reveals that these radiation formulas may only be applied to regions in which the vector potentials are known to satisfy the inhomogeneous wave equation On applying this axiom to the theories, all but Brown's are shown to be fallacious A detailed application of the vector Kirchhoff formula to uniform cylindrical dielectric rods supporting the HE11 mode produces an expression for the far-field radiation pattern, which, when computed, gives good agreement with existing experimental data The analysis allows for dielectric losses and can also be extended to nonuniform dielectric antennas with gradual tapers Fresnel interaction of the apertures and lens effects are considered Finally, some design recommendations for dielectric rod antennas are made
37 citations
TL;DR: In this paper, a general theory of the propagation of higher-order modes on cylindrical surface-wave structures is examined and applied to the dielectric-clad rod, in which the boundary conditions at the guide are specified by an impedance dyadic.
Abstract: A general theory of the propagation of higher-order modes on cylindrical surface-wave structures is examined and applied to the dielectric-clad rod. A theory is developed in which the boundary conditions at the guide are specified by an impedance dyadic. The characteristic equation for the structure is then obtained in terms of the elements of the dyadic. The equation is solved and yields a set of conditions which are satisfied by the values of the dyadic elements at the cutoff points for each of the higher-order modes. A mode without a cutoff frequency is shown to exist on the structure used. The relationship between the guide wavelength and frequency has been verified experimentally.
11 citations
DOI•
01 Jan 2016
TL;DR: Thesis (Ph.D. as mentioned in this paper ) at the University of Adelaide, School of Electrical and Electronic Engineering, 2016, has been published in the Australian Journal of Distributed Sensor Networks.
Abstract: Thesis (Ph.D.) -- University of Adelaide, School of Electrical and Electronic Engineering, 2016.
8 citations
Cites background or methods or result from "The surface-wave aerial"
...This surface wave propagation was shown to take place for infinite conductivity of the conductor, as speculated by Harms, provided that the surface of the conductor is coated with a dielectric layer [146]....
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...However, Harms [150] showed that a dielectric or magnetic coated conductor of infinite conductivity can support the propagation of electromagnetic waves with low loss [146]....
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...Contrary to prevailing understanding, it will be shown that a bare conductor can sustain two dominant modes: the well-known symmetric TM01 mode, and the asymmetrical HE11 mode, which hitherto has been overlooked and forgotten due to early analysis [141, 142] which concluded that higher order modes are highly damped by eddy currents and do not propagate [143, 144] or that hybrid modes cannot exist at all on a bare conductor [145, 146]....
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...Contrary to that which has been known or demonstrated previously [143-146], this study will demonstrate that an acupuncture-like needle can sustain the propagation of the two dominant modes, and that an artificial dielectric coating can lower or avoid losses....
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...Adapted from Hersch [146]....
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TL;DR: The results of analytical and numerical study of the modes propagating on an impedance-surface circular cylinder are communicated in this article, where the well-known axially symmetric Sommerfeld's mode, having a single azimuthal variation, can propagate at any frequency.
Abstract: The results of analytical and numerical study of the modes propagating on an impedance-surface circular cylinder are communicated. Besides the well-known axially symmetric Sommerfeld's mode, another hybrid mode, having a single azimuthal variation, can propagate at any frequency. For a realistic cylindrical conformal antenna, the both wavenumbers are quite comparable. This may cause additional coupling between array antenna elements.
5 citations
Cites background from "The surface-wave aerial"
...In [8], an erroneous assertion on the HE11 low-frequency cutoff was found....
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References
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Book•
01 Dec 1995
TL;DR: Theory of dielectric measuring techniques and their applications as mentioned in this paper Theoretical and practical applications of die-lectric materials include: insulation strength of high pressure gases and of vacuum liquid dielectrics plastics as dielectors ceramics dielectrices in equipment, capacitors in capacitors rubber and plastics in cables problems of the cable engineer, and the requirements of the armed forces.
Abstract: Theory dielectric measuring techniques dielectric materials and their applications - dielectric materials insulation strengths of high pressure gases and of vacuum liquid dielectrics plastics as dielectrics ceramics dielectrics in equipment dielectrics in power and distribution equipment dielectrics in electronic equipment dielectrics in capacitors rubber and plastics in cables problems of the cable engineer dielectric materials as devices rectifiers piezoelectric transducers and resonators magnetic and dielectric amplifiers memory devices dielectric requirements of the armed forces tables of dielectric materials
1,614 citations
TL;DR: In this paper, the applicability of non-radiating surface waves for transmission lines is investigated and the information necessary for the design of such lines is given and the agreement between the theoretically expected transmission losses and the measured transmission losses is checked.
Abstract: In this paper the applicability of non‐radiating surface waves for transmission lines is investigated. Two types of waves are considered. The first one, originally studied by A. Sommerfeld, is guided by a cylindrical conductor of finite conductivity. Although this wave type has (under comparable conditions) much lower attenuation than the waves in coaxial cables or rigid wave guides, its practical application is restricted by the fact that the extension of the field is very large. Efficient excitation and undisturbed propagation of this wave mode are feasible only for very high frequencies. The other wave type considered in this paper has not been treated in the literature. It is guided by a conductor which is coated with a dielectric layer or the surface of which is otherwise modified; for example, by being threaded. The field of this wave type has a structure similar to that of Sommerfeld's wave, but the extension of the field can be controlled by the surface modification. Thus low loss transmission lines on the basis of this wave type become feasible for frequencies above 100 megacycles. The information necessary for the design of such lines is given and the agreement between the theoretically expected transmission losses and the measured transmission losses is checked.
966 citations
310 citations
01 Jul 1952
TL;DR: In this article, the amplitude of a surface wave which is excited by a dipole or any other power source can be determined without solving the entire excitation problem, and it is shown that surface waves are actually contained in complete solutions of excitation problems of cylindrical surface waveguides.
Abstract: It is shown that surface waves are actually contained in complete solutions of excitation problems of cylindrical surface waveguides. The total field can be divided into surface waves and a supplementary field; these field components satisfy certain orthogonality relations between each other. The amplitude of a surface wave which is excited by a dipole or any other power source can be determined without solving the entire excitation problem.
85 citations
56 citations