Andrea Neto

Planar circularly symmetric EBG structures for reducing surface waves in printed antennas

This paper discusses the design and analysis of planar circularly symmetric (PCS) electromagnetic band gap (EBG) structures for reducing the surface waves excited by printed antennas on dense dielectric substrates. The key advantage of the circularly symmetric geometries is that a surface wave generated by a source located at its center experiences the same band gap effect in all radial directions. To obtain simple design rules of the PCS-EBGs for the optimization of the bandwidth, an equivalence is established between 2-D-EBGs and PCS-EBGs. Integrated planar printed antennas with bandwidths up to 20% are designed, manufactured and tested.

Ultrawide-band properties of long slot arrays

In this paper the ultrawide-band properties of a long slot array are described. The study provides the rigorously derived Greens function (GF) for an infinite long slot array. From these GF active impedances and radiation patterns for various cases were obtained. The ultrawide bandwidths and the array performances of such apertures are highlighted, providing physical insights to understand the mathematical formulation throughout the paper.

A truncated Floquet wave diffraction method for the full wave analysis of large phased arrays. I. Basic principles and 2-D cases

This two-part sequence deals with the formulation of an efficient method for the full wave analysis of large phased array antennas. This is based on the method of moments (MoM) solution of a fringe integral equation (IE) in which the unknown function is the difference between the exact solution of the finite array and that of the associated infinite array. The unknown currents can be interpreted as produced by the field diffracted at the array edge, which is excited by the Floquet waves (FWs) pertinent to the infinite configuration. Following this physical interpretation, the unknown in the IE is efficiently represented by a very small number of basis functions with domain on the entire array aperture. In order to illustrate the basic concepts, the first part of this sequence deals with the two-dimensional example of a linearly phased slit array. It is shown that the dominant phenomenon fur describing the current perturbation with respect to the infinite array is accurately represented in most cases by only three diffracted-ray-shaped unknown functions. This also permits a simple interpretation of the element-by-element current oscillation, which was described by other authors.

UWB, Non Dispersive Radiation From the Planarly Fed Leaky Lens Antenna— Part 1: Theory and Design

An efficient directive antenna is described that can be used to realize essentially non dispersive links over extremely large bandwidths. The antenna is a significantly enhanced version of previously proposed Leaky Lens antennas that use a frequency independent leaky slot radiation mechanism. A theoretical breakthrough now allows the use of this mechanism also in the presence of purely planar structures. This step allows the realization of the feed of a leaky lens antenna in a unique planar structure that is then glued to a standard circularly symmetric elliptical dielectric lens, as integrated technology requires in the mm and sub-mm wave domains. The first part of this sequence deals with a theoretical breakthrough, the consequent antenna concept and a description of the basic physical mechanisms inside and outside the lens antenna. It is shown that Leaky Lens antennas have the potential to be used to realize antenna links over bands exceeding a decade with minimal dispersion, high efficiency and high directivity. The second part of this sequence deals with the demonstration of these claims via the measurement of two prototypes.

A truncated Floquet wave diffraction method for the full-wave analysis of large phased arrays .II. Generalization to 3-D cases

For pt.I see ibid., vol.48, no.3, p.594-600 (2000). This paper deals with the generalization to three-dimensional (3-D) arrays of the truncated Floquet wave (TFW) diffraction method for the full-wave analysis of large arrays. This generalization potentially includes arrays consisting of microstrip excited slots, cavity-backed apertures, and patches. The formulation is carried out first by deriving an appropriate fringe integral equation (IE) and next by defining entire domain basis functions in terms of global-array functions shaped as TFW diffracted rays whose analytical expression is derived on the basis of prototype canonical problems. The efficiency and the accuracy of this method is demonstrated by comparison with the results of an element-by-element full wave approach for a rectangular slot array.

Scanning Performances of Wideband Connected Arrays in the Presence of a Backing Reflector

In this paper, the scanning performances of connected arrays that include backing reflectors are investigated. The comparison between connected dipoles and slots is based on the properties of the corresponding Greens functions (GFs). The investigation reveals that connected arrays of dipoles are better suited to scan to wide angles (45deg), retaining the minimal number of transmit/receive (T/R) modules. This paper quantifies and motivates this preference. Eventually, the theoretical design of a fully efficient, 40% bandwidth (BW), planar array with the lowest possible cross polarization is presented.

Sector PCS-EBG Antenna for Low-Cost High-Directivity Applications

This letter proposes a new topology of antenna based on the use of planar circularly symmetric electromagnetic band gap (PCS-EBG) with different periodicities. These periodicities are used to impose different propagation velocities of the dominant surface waves on different zones of the same dielectric substrate. The control of the dispersion characteristics guides the design together with the definition of a centered feed suitable to excite the surface waves. One prototype has been designed, manufactured and tested to prove the concept.

Effect of internal reflections on the radiation properties and input impedance of integrated lens antennas-comparison between theory and measurements

This paper presents the effect of internal reflections on the beam pattern and input impedance of integrated lens antennas. A silicon lens was designed and manufactured, and measurements were conducted at a frequency of 100 (impedance) and 500 GHz (beam pattern). A frequency-dependence characterization of the beam pattern clearly showed the existence and impact of internal reflections. The measurements confirmed that most of the frequency variations of the beam pattern could be attributed to internal reflections, as predicted by the model. An on-wafer measurement strategy for determining the antenna impedance at millimeter-wave frequencies is presented. The validity of the model was also proven by an excellent match of the input impedance measurements and predictions. Not only the level, but also the oscillation on the impedance curve was predicted accurately. Initial space qualification was performed in the form of thermal cycling.

Infinite Bandwidth long slot array antenna

This work deals with the properties of a long slot array fed by an array of periodically located feeds spaced at a Nyquist interval. The study begins with the rigorous Greens function (GF) of a single long slot which was extended to an infinite array structure. After this, the input impedance properties of the array when fed by an array of /spl delta/ sources are described by simple formulas, which explicitly show a theoretically unlimited bandwidth when there is no backplane.

Progress in Antenna Coupled Kinetic Inductance Detectors

This paper describes the combined Dutch efforts toward the development of large wideband focal plane array receivers based on kinetic inductance detectors (KIDs). Taking into account strict electromagnetic and detector sensitivity requirements for future ground and space based observatories, this work has led to the identification of well-suited coupling strategies based on the use of lens antenna and the demonstration of their feasibility. Moreover, some specific antenna design difficulties that characterize KIDs-based designs have been investigated, and innovative feeds for the focal plane array which could allow the receivers to be sensitive over a decade of Bandwidth have been proposed.