Esperanza Alfonso Alos

• Designer at Gapwaves AB

An ultra-high-gain E-band dual-reflector antenna for 5G backhaul with beam tracking function is proposed in this paper. Beam tracking is achieved by defocussing the feed away from the focus point of the sub-reflector, while keeping the interface with the transmit-receive unit stationary by applying a movable gap-waveguide configuration. The antenna...

This article presents the first use of a multilayer dry film photoresist to fabricate a slot array antenna by micromachining. The proposed fabrication process demonstrates a straightforward and fast method of realizing antenna structures and delicate features with very high accuracy above 100 GHz. The slot array antenna design is based on gap waveg...

This paper presents the design of microstrip-ridge gap waveguide using via-holes in printed circuit boards, a solution for high-frequency circuits. The study includes how to define the numerical ports, pin sensitivity, losses, and also a comparison with performance of normal microstrip lines and inverted microstrip lines. The results are produced u...

There is a lack of suitable numerical ports for the gap waveguides. This study studies the resemblance between the ridge/groove gap waveguide and the conventional hollow ridge/rectangular waveguide, respectively, by using numerical analysis. The dispersion diagrams and characteristic impedances are compared and found to be similar within the stopba...

Gap waveguide technology represents an interesting alternative as low-loss, cost-effective, and high-performance transmission line and package of microwave and millimeter-wave systems. A Ka-band coupled-resonator filter for a radio link diplexer, which requires high selectivity to isolate transmit and receiving channels, is proposed and realized us...

A parabolic cylindrical reflector antenna is proposed in this paper for wireless multi-gigabit communications at 60 GHz. The line feed is realized by a power distribution in parallel plate waveguide (PPW). Inside the PPW waveguide there are metal pin rows forming the contours of an H-plane horn structure in front of a parabolic reflector, where we...

Design of passive components (couplers, filters and antennas) and MMIC packaging validation intended for RF front ends for microwave links at 38 GHz using gap waveguide technology have been shown. The use of this technology allows all-in-one integration of receiver, transmitter, and diplexer including the antenna into one mechanical unit. These ini...

This letter discusses the feasibility of a new type of waveguideconsistingofastripsuspendedonabedofnails.Thebed of nails enforces a stopband, while the strip opens a propagating path that can be used to design circuits and feeding networks for the microwave and millimeter-wave bands. Advantages and draw- backs with respect to existing ridge gap wav...

This paper shows a new interpolation technique to produce infinitely differentiable curves from a finite set of interpolating points. The technique will be very useful for the implementation of higher order numerical and asymptotical methods in computational electromagnetics. In this paper we show the 2D case (for curves). We will present a general...

This study describes the design and experimental verification of the ridge gap waveguide, appearing in the gap between parallel metal plates. One of the plates has a texture in the form of a wave-guiding metal ridge surrounded by metal posts. The latter posts, referred to as a pin surface or bed of nails, are designed to give a stopband for the nor...

In this paper we present a novel butterfly algorithm for the fast computation of integral transforms of oscillatory type. This kind of integral operators are very important when dealing with electromagnetic problems. The algorithm presented here has a computational cost of O(NlogN) and is kernel independent. I. INTRODUCTION Integral transforms are...

Corrugated surfaces have been commonly used to design antennas with low cross polarization or chokes to reduce coupling. Recently, soft and hard surfaces have found novel applications due to its ability to control propagation in a desired way. One of these applications is an oversized waveguide with one single hard wall; from now on Single-Hard-Wal...

High-gain low-profile antennas for microwave and millimeter-wave applications have been a topic of exhaustive research during last decades. More specifically, radial-line slot array-antennas (RLSAs) demonstrated their suitability for massive production in low-cost applications, e.g. TV-DBS. In this context, RLSAs became very attractive due to their...

This paper presents recent advances is a new waveguiding technology referred to as ridge gap waveguides. The main advantages of the ridge gap waveguides compared to hollow waveguides are that they are planar and much cheaper to manufacture, in particular at high frequencies such as for millimeter and submillimeter waves. In these waveguides there a...

A Fast Physical Optics technique is presented for computing the RCS of 2D geometries described in terms of Rational Bezier curves. The algorithm is based on the path deformation technique. The exact integration path is computed analytically, therefore, the highly oscillatory PO integral is transformed into a slowly varying integral with exact accur...

A power divider in ridge gap waveguide technology has been designed to work at 15GHz. Measurements and simulations are provided. Besides, a broad numerical study of the characteristic impedance of a ridge gap waveguide is presented.

The paper presents a new waveguide appearing in the air gap between two parallel metal plates. One of the plates has a metal texture, and confined local waves follow ridges in the texture whereas they are prohibited from propagating in other directions by metal pins in the texture. The pins (or bed of nails) provide a high impedance surface that cr...

This letter reports an experimental study of a gap waveguide which is able to support a plurality of degenerate local quasi-TEM modes. No sidewalls are needed to separate these modes, which is a very useful property in the upper microwave and millimeter-wave bands. The waveguiding media is formed in the gap between a conducting plate and a hard sur...

This communication describes a method of moments formulation to analyze the scattering from corrugated surfaces. The approach is based on the aperture integral equation. Such approach decouples the analysis of the impedance effect of the grooves from the external coupling among grooves and allows us to deal accurately with grooves of any shape. Adv...

The physical optics (PO) approximation is a well-known technique used to analyze very large conducting structures. In scattering problems and radiation of large reflectors, the PO technique provides acceptable accuracy for some applications. This technique allows avoiding the hard solution of the Method of Moment (MoM) linear system by approximatin...

This paper presents a study of the characteristic impedance of a ridge gap waveguide. Ridge gap waveguides belongs to a new metamaterial-based waveguide technology for millimeter and submillimeter waves which emerged recently. A formula for the characteristic impedance of an ideal PEC-over-PMC ridge gap waveguide has been derived. A preliminary num...

An efficient and accurate moment method analysis of a parallel-plate waveguide with one single hard wall using the aperture integral equation (AIE) and the CG-FFT method is presented. This approach is perfectly applicable to new realizations of soft/hard surfaces apart from the classical corrugations. A realization of this waveguide with classical...

This paper presents the design of a simple transition from ridge gap waveguide to coaxial line transition. First, a straight ridge gap waveguide with single transition on end is simulated. Then a ridge gap waveguide with two 90deg bends is simulated with two transitions on each end. Available commercial FDTD simulation tool was used to design the t...

The new proposed ridge gap waveguide can be implemented with different types of periodic surfaces. In this manuscript we have shown how to use the mushroom-type EBG surface to this aim besides the previously used ldquoFakir's bed of nailsrdquo. The bandgap of the periodic structure inside the parallel plate gives the upper limit of the band of oper...

This paper presents a numerical analysis of a ridge gap waveguide. Ridge gap waveguides belongs to a new metamaterial-based waveguide technology for millimeter and submillimeter waves which emerged recently. The magnetic boundary condition or high-impedance surface (ideally a PMC) has been realized by means of a bed of nails as parallel-plate mode...

This paper shows a fast and efficient algorithm to compute the physical optics integral on smooth large surfaces of arbitrary shape. The algorithm is applied to several nurbs surfaces. The CPU time and accuracy is compared with the first order FPO. The algorithm consist of dividing the surface in smaller triangles and apply a quadratic approximatio...

This letter presents a new metamaterial-based waveguide technology referred to as ridge gap waveguides. The main advantages of the ridge gap waveguides compared to hollow waveguides are that they are planar and much cheaper to manufacture, in particular at high frequencies such as for millimeter and sub- millimeter waves. The latter is due to the f...

An oversized rectangular waveguide with one hard wall was previously demonstrated to be suitable for feeding a planar slot array because it has higher-order-mode-killing properties, i.e. it supports propagation of a single quasi-TEM parallel-plate-type mode, and no higher order modes. In the present paper we detect instead many local quasi-TEM wave...

The PO approximation is a well-known technique used to analyze very large conducting structures. In scattering problems and radiation of large reflectors the PO technique provides acceptable accuracy [1-2] for some applications. This technique allows to avoid the hard solution of the MoM linear system by approximating this solution by the explicit...

This paper shows a 3D fast physical optics method for computing the backscattered field of a parabolic surface with polygonal contour. The Path deformation technique is used to convert the highly oscillatory PO integral into a slow varying function. A Gaussian quadrature with a number of sample points no frequency dependent is used to compute the i...

The optimization of a large finite in size hard surface on the bottom face of a parallel-plate waveguide, by using a full- wave code based on the method of moments and the CG-FFT method, is presented. The objective is to achieve quasi-TEM propagation within the guiding structure, proposed by the authors, to feed a slot array.

A new 3D fast physical optics method is presented for computing the diffracted field by a conducting plate with arbitrary contour. This is a fast and accurate method both in low and high frequency. This method combines classical path deformation technique with Jacobi orthogonal polynomial approximation. © 2007 Wiley Periodicals, Inc. Microwave Opt...

We propose a novel planar slot-array antenna fed by a new guiding structure which forces a quasi-TEM mode within an oversized rectangular waveguide. To achieve a quasi-TEM mode throughout the waveguide a hard surface is placed on the bottom surface of the waveguide while the radiating slots are at the upper face. The waveguide is able to propagate...

The basic structure of a RLSA consists of a set of slots placed on the upper face of a simple parallel plate waveguide. Such guide is fed at its centre, typically by a coaxial probe. The suitable arrangement of slots provides the desired radiation pattern and polarization. However, while the circularly-polarized RLSA (CP-RLSA) has been successfully...

In this paper we describe a numerical procedure to analyze finite-size hard surfaces within parallel-plate waveguides. The code developed is used to optimize the hard surface to force the propagation of a quasi-TEM mode in oversized waveguides. Application of this structure to planar slot arrays will be shown.

A new algorithm to increase the resolution in the reconstruction of equivalent currents from spherical near-field measurements is proposed. The algorithm obtains the non-visible part of the plane- wave spectrum used for the reconstruction. This is achieved by means of a band-limited extrapolation method, the Papoulis-Gerchberg algorithm, and the re...

This letter proposes a novel dual linearly polarized single layer radial-line slot-array antenna (D-LPRLSA). The dual polarization is achieved arranging the slots in concentric ellipses and feeding the structure with two ports at the ellipses foci. Antenna ports must be accessed through a 180deg hybrid ring to obtain the dual behavior

This paper proposes new topologies of linearly polarized radial-line slot-array antennas (LP-RLSA) which uses slot-dipole pairs as radiating elements. Firstly, the basic design of the antenna with cancelling slots is considered and its benefits and drawbacks are highlighted. The evolution of this configuration leads to more convenient arrangements...

We propose a novel slot-array antenna fed by a new guiding structure which forces a quasi-TEM mode within an oversized rectangular waveguide using a hard surface on the bottom face of the waveguide. In this paper, our objective is the evaluation of the order of magnitude of slot internal mutual coupling, as well as its interaction with the propagat...

We propose a new structure to force a quasi-TEM mode to propagate inside an oversized closed rectangular waveguide. A hard surface is employed. Simulation results confirm a good performance. The structure means a promising first step toward a waveguide slot array with high efficiency and directivity

This paper proposes a new design of linearly polarized radial-line slot-array antennas (LP-RLSA) which uses loading strips and cancelling slots. The combination of both techniques provides wider impedance bandwidth with high radiation efficiencies. The suitable design of the antenna elements reduces the excitation of cancelling slots and consequent...

A method is introduced for reducing the dependence on matrix formation time, solution time and computer storage in the Method of Moments (MoM) for high frequency electromagnetic scattering problems. This method combines Asymptotic Phasefront Extraction (APE) with an efficient calculation of the impedance integrals.

An efficient CG-FFT method based on multilevel block-Toeplitz matrices is presented to analyze the scattering and radiation from large finite arrays of arbitrarily shaped microstrip patches. The rooftop basis function on the patches' surface and Galerkin's method are applied to discretize the mixed potential integral equation (MPIE) and establish a...