Waveguide Leaky-wave Antenna Research Articles

A Modified Pole-Zero Technique for the Synthesis of Waveguide Leaky-Wave Antennas Loaded With Dipole-Based FSS

An extension of the pole-zero matching method proposed by Stefano Maci for the analysis of electromagnetic bandgap (EBG) structures composed by lossless dipole-based frequency selective surfaces (FSS) printed on stratified dielectric media, is presented in this paper. With this novel expansion, the dipoles length appears as a variable in the analytical dispersion equation. Thus, modal dispersion curves as a function of the dipoles length can be easily obtained with the only restriction of single Floquet mode propagation. These geometry-dispersion curves are essential for the efficient analysis and design of practical EBG structures, such as waveguides loaded with artificial magnetic conductors (AMC) for miniaturization, or leaky-wave antennas (LWA) using partially reflective surfaces (PRS). These two practical examples are examined in this paper. Results are compared with full-wave 2D and 3D simulations showing excellent agreement, thus validating the proposed technique and illustrating its utility for practical designs.

Design of tapered leaky-wave antennas in hybrid waveguide-planar technology for millimeter waveband applications

Different types of waveguide leaky-wave antennas, asymmetrically perturbed with printed-circuits, are studied in this paper. The capability to modify the leakage constant of the excited leaky-wave mode, while maintaining unchanged its phase constant, is studied in detail for each design. Several slot and strip configurations are proposed, in which the width and the position of the planar printed circuit perturbation is modified along the length of the antenna to obtain different tapering topologies. All of them are mechanically flexible to realize, thus simplifying the manufacturing process for millimeter wavelengths applications. The two-dimensional method used for the analysis is accurate for any geometry of the planar perturbation, and also allows for the computation of the whole spectrum of modes in these open waveguides. This makes possible to predict the appearance of unwanted channel-guide modes, and also allows for the study of the coupling effect between the desired leaky-wave mode and them. A tapered design is performed and compared with full-wave three-dimension simulations to validate the proposed technology.

Pattern reconfigurable leaky-wave antenna design by FDTD method and Floquet's Theorem

A pattern reconfigurable millimeter-wave coplanar waveguide leaky-wave antenna is designed by using the finite-difference time-domain (FDTD) method combined with Floquet's theorem and the simple linear interpolation technique. The concept of equivalent period is presented for mixed-periodic structures. The novel design process results in a reduction in the design time compared with that of the traditional FDTD method.

A novel theory for dielectric-inset waveguide leaky-wave antennas

A type of leaky-wave antenna that is particularly suitable for applications in the millimeter-wave range is analyzed. The objective of this work is to provide a practical and accurate theory for the design of this class of antennas. The analysis procedure is based on the development of a novel, multimode transverse equivalent network representation. All mutual coupling effects are rigorously taken into account. A single dispersion relation is derived via a transverse resonance procedure, and the complex dispersion behavior of the antenna is obtained through its numerical solution. Useful approximate initial design formulas are given, and a detailed parametric analysis is carried out, showing the effects of changes of all the structural parameters. The results obtained indicate that the structure, in addition to being mechanically simple to realize, exhibits a very flexible electrical behavior. The theory developed, therefore, is a powerful tool for the design and optimization of this class of antennas. >