Alexander Herschlein

A photonic bandgap (PBG) structure for guiding and suppressing surface waves in millimeter-wave antennas

Periodic and regular metal posts, a photonic bandgap (PBG) structure for guiding surface waves in a parallel-plate waveguide is proposed. The isotropic PBG structure is applied to the design of an asymmetric parallel-plate waveguide Luneburg lens (APWLL). The relation between the dimensions of the metal posts and the required refraction index in the lens is derived with transmission-line theory and the transverse resonance method. Different lattices for the entire lens are also investigated. For verification, an antenna for a 76.5 GHz adaptive-cruise control radar is fabricated, consisting of an APWLL, a primary feed, and symmetric corrugated flares to improve the property of the antenna in elevation. Measured results verify the PBG structure design in the APWLL.

Electromagnetic scattering by multiple three-dimensional scatterers buried under multilayered media. I. Theory

A general procedure is developed for the analysis of electromagnetic (EM) scattering by multiple three-dimensional (3D) dielectric and/or conducting objects buried under one-dimensional (1D) multilayered media. In this first part of a two-part paper, general closed-form formulations for the electric fields excited by an arbitrarily oriented electric dipole under the layered media are first presented, from which electric-field integral equations for the buried dielectric objects, pure conducting objects, and their combinations are then obtained, and the scattered electric fields in the upper space are formulated. Finally, the physical significance of the above formulations is discussed. In the second part, numerical implementations for these integral equations and the scattered fields are investigated.

Detection of Antipersonnel Mines by Using the Factorization Method on Multistatic Ground-Penetrating Radar Measurements

The factorization method (FM) has been applied to measurement data from a multistatic ground-penetrating radar operating in close proximity to the ground, which was used in a measurement campaign on the Joint Research Centre mine test lane in Ispra, Italy. This paper is targeted toward a future hand-held demining system. The according space limits restrict an independent positioning of transmit and receive antennas. Hence, very small multistatic datasets are obtained, representing a difficult case for the reconstruction with the FM

Offset cylindrical reflector antenna fed by a parallel-plate Luneburg lens for automotive radar applications in mm-wave

Using a single offset cylindrical parabolic reflector and an improved parallel-plate Luneburg lens, a novel antenna is developed for automotive radar in the mm-wave range. By adding linearly- or circularly-corrugated extensions to the parallel-plate Luneburg lens, a cylindrical wave illuminates the reflector, and hence good performances are achieved. Using GO, the aperture field of the antenna is found and then far-fields of the entire antenna are derived using the aperture field integration method. Design procedures of the entire antenna are presented. For verification of design rules and simulation, a prototype antenna for an adaptive cruise control (ACC) radar at 76.5 GHz is designed and measured. The antenna has properties of a relatively wide scan angle and multiple beams.

A Parallel-Plate Luneburg Lens Sensor Concept for Automatic Cruise Control Applications

A new system concept for Automatic Cruise Control (ACC) is introduced which is able of covering a wide field-of-view and offers the ability of high azimuth resolution for the detection of several object within one range cell. The system makes use of digital beamforming on-receive-only to simplify the hardware requirements and to facilitate the use of high efficiency processing techniques.

Solving moment method problems by partitioning

Efficient solutions of electromagnetic field problems are more and more needed as numerical methods are increasingly applied. A partitioning of the method of moments (MoM) matrix allows one to efficiently apply the MoM to several special classes of problems. The first class is an optimization problem where small parts of a big system have to be tuned, whereas the bigger part remains constant. The second class are problems too big to fit into the computers memory. There, the partitioning allows one to efficiently use internal and external memories and to minimize data transfer between the two. After an outline of the method two numerical examples are presented. The first is the optimization of an antenna on top of a handset, the second is a very large electromagnetic problem which does not fit into the computers memory.

Exposition in Penthauswohnungen verursacht durch Mobilfunkbasisstationen

The widespread use of mobile communications in conjunction with an increasing number of new sites for base stations causes sometimes concern. The potential hazard of a mobile base staton is often estimated to be greater, the closer it is to a residential house. This article deals with the scenario where a mobile base station is directly mounted on the flat roof of a penthouse. Far field calculations cannot be applied because of the proximity of the roof to the antenna. Furthermore the damping cannot be given in general due to different angles of incidence onto the various building materials. Individual calculations are necessary. In this article a method for solving the problem is presented together with calculated power densities for different situations. Für die Dokumentation EMVU / GSM / Vollwellenmodellierung / geschichtete Medien

Electromagnetic scattering by arbitrary surfaces modelled by linear triangles and biquadratic quadrangles

One method to solve general three-dimensional electromagnetic problems is the method of moments applied to integral equations. This method approaches the unknown surface currents by basis functions, set up on the interpolated surface of the scatterers. Mostly, one uses roof-top functions as basis functions. Various geometrical interpolation schemes have been proposed like the triangular patch by Rao et al. (1982). In this paper biquadratic functions are used. It compares these two interpolation schemes by means of the RCS of a sphere. Three cases are considered: PEC, dielectric lossy sphere, and the numerically problematic case of a low dielectric contrast.