Surface Wave Antenna Research Articles

A novel surface-wave antenna design using a thin periodically loaded ground plane

This paper presents a novel surface-wave antenna that realizes a low-profile configuration using a thin patch-loaded grounded slab, which has an in-phase reflection coefficient for plane waves, but no band gap for surface waves. When a dipole antenna is horizontally positioned near this artificial ground plane, it works like a transducer that converts the energy from the feeding probe into surface waves in the ground plane. The propagation and diffraction of the surface waves generate a monopole-type radiation pattern. The attractive antenna height, which is less than 10% of a typical monopole antenna, is desirable for wireless-communication systems. The performance of the surface-wave antenna is demonstrated through both the FDTD simulations and the measured results. © 2005 Wiley Periodicals, Inc. Microwave Opt Technol Lett 47: 240–245, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21136

A reduced surface-wave twin arc-slot antenna for millimeter-wave applications

A simple, uniplanar, reduced surface-wave twin arc-slot antenna element for millimeter-wave (mm-wave) integrated circuit antenna systems is presented. This design allows for almost complete surface-wave cancellation and resonance to be achieved simultaneously. Measured far-field radiation patterns on an electrically thick substrate are in very good agreement with theory and show little evidence of surface-wave propagation.

Mutual coupling between reduced surface-wave microstrip antennas

An investigation of the mutual coupling between reduced surface-wave microstrip antennas is presented and compared with that for conventional microstrip antennas. Numerical results are presented from a theoretical analysis of the mutual coupling along with confirming experimental results. It is shown that for electrically thin substrates, the space-wave coupling, not the surface-wave coupling, is predominant for typical element spacing, for both the conventional and reduced surface-wave antennas. In addition, the mutual coupling behavior is examined using an asymptotic analysis, which demonstrates how the coupling falls off much faster with patch separation for reduced surface wave antennas compared to conventional microstrip patch antennas.

Theory of Antenna Radiation from Photonic Band-Gap Materials

ABSTRACT A unified formulation of antenna radiation from photonic band-gap (PBG) materials is described in this paper. An analytical array scanning method is applied to formulate the boundary-value problem associated with source interaction with infinite periodic structures. A double vector-integral equation formulation in conjunction with multi-stage moment methods is introduced to characterize the current distribution over antenna elements, the near fields, and associated circuit parameters of interest. Asymptotic method is used to find the far-zone radiated waves and the periodic guided waves, which are used subsequently to determine the antenna radiation characteristics including gain (directivity) patterns, efficiency, and periodic guided wave power pattern. Of particular interest is the photonic band-gap effect to the periodic guided waves. Potential high-gain surface wave antenna using a PBG substrate is also discussed.

Analysis of corrugated surface wave antenna using hybrid MOM/UTD technique

A new efficient technique for the analysis of corrugated surface wave antennas with infinite ground plane fed by a parallel-plate waveguide is presented, termed the hybrid method of moments/uniform geometrical theory of diffraction (MOM/UTD) technique. The relative power pattern obtained using the method is compared with the patterns obtained from the previous approximate solution and experiment. The power pattern of the presented method agrees more closely with that of the experiment, compared with that of the previous approximate solution.

Novel surface-wave antenna

A circular array of a large number of electrically short vertical dipoles of which only two are driven is described and analysed. The relevant parameters include the length and radius of the identical elements, the distance between adjacent elements and their number. A judicious choice of the parameters can establish one of many possible resonant modes for the current amplitude distribution around the array and generate a horizontally omnidirectional field pattern with very high vertical directivity. Applications as a surface-wave generator are discussed. Although the array is not a broadband device, the possibility of operating at several discrete frequencies using the same construction may be an advantage for some applications.

Reflection analysis for planar surface wave antennas with different tapering profiles

The reflection characteristics of the planar surface wave antennas with different tapering profiles are analyzed by a method which transforms the radiation problem into the transmission problem of the eigen mode in the partially dielectric filled planar waveguide to avoid the difficulty of the field source problem which is met in the traditional analysis. As a result, the analysis procedure is tremendously simplified. The effect of the tapering profile on the reflection property is carefully investigated and extensive numerical results are given to establish useful guidelines for the design of the planar surface wave antennas.

Periodic metal plate-loaded dielectric slab antenna with broadside radiation

Wave guiding properties of a periodic metal plate-loaded dielectric slab structure are investigated for obtaining surface wave antennas with broadside radiation and low voltage standing wave ratio (VSWR) characteristics. A novel technique is proposed in which dielectric phase transformers play an essential role for realizing a uniform phase distribution on the radiating aperture which is required to achieve broadside radiation. A quarter-guided wavelength spacing of the metal plates guarantees the suppression of reflections at the input port. On the basis of the theoretical results obtained, two types of antennas have been designed at 10 GHz, one having the exponential aperture distribution, the other the uniform aperture distribution. The overall antenna efficiency of the latter type has been found to be 53%, exhibiting a practical performance at microwave frequencies. >

Transverse Coupling Between Two Surface Wave Antennas

A method has been devised to derive the coupling coefficient between two infinitely long perfectly conducting surface-wave antennas such as disc-on-rod antennas. This method is based on the Lorentz reciprocity theorem and on the equivalence principle. The theoretical derivation of a general expression for the coupling coefficient as well as numerical results for disc-on-rod antennas are presented in this paper. Results based on this method have been found to be in good agreement with those obtained from an analysis of element interaction in a broadside array of traveling-wave end-fire antennas.

Polarization properties of the axial mode helix antenna

The helix is considered as a surface wave antenna. A network model of the infinite structure provides a simple vehicle to view the fields behavior. The far-field polarization properties are examined in detail, and it is shown how they depend on the surface wave structure and the open and feed end configurations. By suitably arranging the antenna ends, perfect endfire polarization purity can be produced independent of antenna length (i.e., number of turns). Inclusion of a dielectric core decreases the cross polarized radiation in off-axis directions. Theoretical and experimental patterns illustrate these results.

Longitudinal coupling between elements in a disc-on-rod antenna array

A general expression is proposed for the coupling of surface wave antennas based on the equivalence principle and on the reciprocity theorem. A particular application is presented for disc-on-rod antennas, and the coupling coefficient is evaluated as a function of frequency, the array parameters and the element parameters. A physical explanation of the results is suggested.

Improvements to a surface-wave antenna measurement range with troublesome site effects

A surface-wave antenna measurement range used for ship antenna modelling work has been improved by the development of a novel source antenna. The antenna, a large ‘half-truncated’ corner reflector, has reduced unwanted range reflections to allow phase measurements to be made to an accuracy of approximately ±2°. Also, the screening effect of the reflector allows an adjacent range on the same reflecting ground plane to be operated simultaneously without noticeable effect on the surface-wave range performance.

Dielectric sphere-loaded radial surface-wave antenna

The results of an experimental and theoretical study of the radiation characteristics of a high-gain antenna feed system are reported. The feed system consists of a homogeneous dielectric sphere offset in front of the aperture of a radial surface-wave horn formed by a E-plane sectoral horn with its bottom plane having a layer of dielectric coating keeping the top plane truncated at a height where the field concentration is almost negligible. Firstly, the radiation characteristics with on-axis gain of the surface-wave E-plane sectoral horn alone are derived for TE10 mode excitation, from an electric vector potential on the basis of the vector diffraction formula. Then the radiation characteristics of the feed system are derived by treating the system as a microwave lens illuminated by an aperture source. Theoretical results and established in good agreement with experimental results of radiation pattern and gain measurements. It is concluded that radial surface-wave horn antennas have on-axis gain in excess of that of conventional E-plane sectoral horns, and also that the radiation characteristics of the surface-wave horn are improved further with greater directivity, increased on-axis gain and reduced side.lobe levels (beyond 90°, the side lobo level is of negligible magnitude being leas than − 40 dB) due to the offset dielectric sphere at its aperture.

Experimental evaluation of an array technique for zenith to horizon coverage

An experimental study of a new array concept with application to providing low cost efficient antennas with hemispherical coverage for aircraft to satellite communication links is described. The combined array-surface wave antenna consists of 64 waveguide elements scanned conventionally except at endfire. At endfire the array is shorted to become a corrugated surface-wave antenna and excited by an eight-element feed to provide a directional beam near the horizon. The array is rotated to give hemispherical coverage.

Radiation Characteristics of a Dielectric Sphere Loaded Surface-Wave Horn Antenna

The analytical and experimental investigations into the radiation characteristics of a high-gain antenna system are made. The antenna system consists of an H-plane sectoral horn with a layer of dielectric coating at the bottom E-plate (the top plate is removed) as a surface-wave source and a dielectric sphere placed off-set in front of the horn aperture. The radiation characteristics are derived by treating the antenna system as a microwave lens illuminated by an aperture source. There is good overall agreement between theoretical and experimental results of radiation pattern and gain measurements especially for dielectric spheres of diameters less than two wave lengths. It is observed that the on-axis gain of the surface-wave horn antenna is increased due to dielectric sphere loading. The system also possesses reduced 3-dB beamwidth. The proposed antenna system can be used either as a highly directive variable beamwidth feed for parabolic reflectors or as a convenient and effective high-gain source of radiation of UHF and microwave frequencies.

A Radial Cylindrical Surface Wave Antenna

A new type of surface wave antenna utilizing an unsymmetrical radial surface wave is proposed in this communication. The antenna consists of an inductively reactive surface coincident with the ρ-plane of a cylindrical co-ordinate system. This surface is confined between two conducting vertical walls. The surface wave field propagating radially outward in such a structure is studied inside the antenna. The on-axis gain of such an antenna is calculated theoretically and compared with experimentally observed value. It is found that such an antenna has several desirable features.

Numerical solution of nonuniform surface wave antennas

An integral equation is used to numerically study microwave surface wave antennas. The source is chosen as a horizontal magnetic line current which is placed parallel to a planar surface having a one-dimensional nonuniform surface reactance. The integral equation is numerically solved exactly taking full account of radiation from both the feed and the termination, and their mutual interaction. By varying the profile of the surface reactance and the antenna length, radiation characteristics such as directivity, beam width and sidelobe level are discussed. The optimum excess phase delay is found to be about <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">\pi/3</tex> for an antenna length of <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3\lambda_{0}</tex> , gradually increasing to <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">\pi/2</tex> for a length of <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">8\lambda_{0}</tex> . When a feed transition in the reactance profile is used to achieve a good surface wave launching efficiency near the source, the first sidelobe can be reduced to less than-10 dB below the main beam level with little effect upon the directivity. Optimum reactance profiles are suggested for antennas from <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3\lambda_{0}</tex> to <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">8\lambda_{0}</tex> long.

Book reviews - Continous transactions in open waveguides

This monograph is devoted to the investigation of surface wave propagation along guides with inhomogeneous sections; where the guide parameters vary gradually in the direction of propagation. Practical cases of continuous transitions are, for instance, the launching of surface waves on a single wireline and surface wave antennas. The material presented in this monograph is in essence is done by the work of the author and his associates which was published in Russia during the years 1960 to 1965.

Experimental resolution of surface-wave antenna radiation into feed and terminal patterns

Experimental resolution of surface-wave antenna radiation into feed and terminal patterns

Surface-wave radiation from a corrugated horn

An expression for the radiation pattern of a surface-wave antenna given by Andersen has been checked experimentally by considering the radiation from the finite aperture of a corrugated horn which supports only a slow hybrid mode