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

Theoretical investigation of cylindrical dielectric-rod antennas

This paper presents a robust and easy manufacturable dual linear-polarized dielectric waveguide antenna (DRA) for the 24 GHz industrial, scientific, and medical band. Dual-polarized operation is achieved by utilizing a square metal waveguide and a conical horn for exciting the surface wave on a tapered dielectric rod. In order to couple a signal into the square waveguide, an innovative dual-polarized, aperture-coupled microstrip-to-waveguide transition is shown. Additionally, two kinds of radomes, i.e., a foam radome and a half-wave wall monolithic radome are presented to protect the DRA. The antenna achieves a 10 dB bandwidth of 1.7 GHz and a gain of 11.5 dB including losses caused by the transitions and connectors. The sidelobe level and the cross-polarization level are lower than −25 and −26 dB, respectively. Designs and measurement results of all components are described in detail in this paper.

A 24 GHz Dual-Polarized and Robust Dielectric Rod Antenna

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.

http://ieeexplore.ieee.org/iel5/5244565/5245232/05245238.pdf

The surface-wave aerial

The present paper deals with the H-Plane Sectoral Solid Dielectric Horn Antenna. Attempts have been made to determine theoretically the approximate surface fields (Ampli tude and Phase) under several simplifying assumptions. A comparison has been made between calculated and experimentally observed values of one of the field components for both amplitude and phase at the front aperture of the antenna. A fairly good agreement has been obtained between them.

Surface Fields of the H-Plane Sectoral Dielectric Horn Antenna

This paper deals with the H-plane hollow sectoral dielectric horn antenna. The metallic wall of the metal horn antenna is replaced by dielectric sheets to obtain this type of antenna. Attempts are made to determine theoretically the approximate fields on the aperture of the antenna under several simplifying assumptions. A comparison is made between theoretically calculated and experimentally observed values for one of the components (the amplitude) at the front aperture of the antenna.

Near-field analysis of H-plane hollow sectoral dielectric horn antennas

This paper describes theoretical and experimental work carried out in the Admiralty Signal Establishment, and at the same time includes all the relevant material that the authors have been able to extract from German reports. It was decided to carry out this investigation when it became known that considerable importance had been attached to dielectric-rod aerials in Germany during recent years. The material of German origin is taken mainly from a translation by the authors of a paper by Mallach of the Vierjahresplan Institut fur Schwingungsforschung, Berlin.The fundamental principles governing the radiation characteristics of dielectric rods are considered, and brief reference is made to other dielectric aerials.

D.F. Halliday

Papers

Dielectric-rod aerials