1,721,369 research outputs found
Rigorous and efficient full-wave analysis of trapezoidal patch antennas
No full textA rigorous full-wave analysis in the spectral domain
for trapezoidal patch antennas is presented in this paper. Particularly,
a new set of entire domain basis functions for an efficient
implementation of the method of moments (MoM) is carried out
by properly imposing the boundary conditions. The simulated results
obtained through the presented method are compared to the
measurements showing a good agreement. Finally, a parametric
analysis of the main antenna features (matching, radiation pattern,
cross-polarization levels) is also carried out
Design of high-performing microstrip receiving GPS antennas with multiple feeds
No full textIn this letter, we present the design of two new high-performing microstrip receiving antennas for the Global Positioning System (GPS). Both layouts proposed here are based on the employment of multiple feeds in order to improve the polarization purity and the pattern symmetry, thus leading to an improved accuracy of the system. The first antenna configuration consists of a truncated-corner squared patch with concentric rings of miniaturized magnetic resonators in order to suppress the surface wave contribution and reduce the back-radiation of the antenna. The second radiator consists of a circular patch antenna with four feeds and loaded with a number of vias in order to improve the front-to-back ratio. Full-wave numerical simulations are presented to show the effectiveness of the proposed design in terms of impedance matching, polarization purity, antenna gain, front-to-back ratio, and shape of the radiation pattern
L’impiego di metamateriali per aumentare considerevolmente la trasmissione attraverso un piccolo foro in uno schermo opaco
No full textIn this work, we theoretically and numerically show the role of
properly selected pairs of metamaterial layers, one located in the front and the
other in the back surface of a small sub-wavelength hole in a conducting
opaque screen. In recent years, there have been experiments in the optical
regime conducted by several groups of physicists all over the world showing
how an appropriately designed periodic corrugation on a metallic opaque
screen leads to significant increase of the power transmission through a subwavelength
hole. Oliner, Jackson and their co-workers explained and justified
this power enhancement as the result of the excitation of the leaky waves
supported by the corrugated screen. In the present work, we suggest a different
configuration using metamaterial bilayers covering the entrance and the exit
face of the hole in a flat PEC screen. In this setup, one pair of metamaterial
layers effectively “collects” the power of the incident wave and concentrates it
at the entrance of the hole, the other pair of layers at the exit face further
increases the anomalous tunneling and re-shapes the radiation patterns at the
receiver side. Conditions for the optimal transmission and certain physical
insights will be presented, together with numerical results confirming our
theory
Parametric analysis of slot-loaded trapezoidal patch antennas
No full textSlot-loaded trapezoidal patch antennas are analyzed
in order to achieve a multifrequency operation. A moment
method formulation based on new analytical entire domain basis
functions is developed and compared to the one involving the
RWG triangular discretization. The numerical results obtained
through the new efficient implemented code are compared to the
measurements showing a good agreement. A parametric analysis
of such antennas is also presented leading to useful design graphs
showing the main antenna properties (resonance frequencies,
cross-polarization levels, matching, etc.) as a function of the patch
geometrical dimensions, symmetric collocation of the slots on the
patch, and slot dimensions
Design of polygonal patch antennas for portable devices
No full textIn this paper, extending the design technique presented by the authors in a previous work, we propose the study of a new family of polygonal patch antennas for portable devices of communication systems. Such antennas are suitable to be mounted in modern terminals, enabling wideband/multi-frequency operation and new multimedia features. The desired electromagnetic behaviour of the proposed radiators is obtained by adding either shorting posts, properly located between the polygonal patch and the ground plane, or circular slots, drilled at the appropriate position on the patch surface. Circular slots are also useful to easily accommodate a photo-camera in the terminal, in order to enable multimedia services and video calls. Some practical layouts of polygonal patch antennas to be used in: a) modern PDAs and Smart Phones integrating cellular phone operation and wireless functionalities; b) UMTS terminals integrating also GSM functionalities, are, finally, presented. The effectiveness of the proposed designs is confirmed through proper full-wave numerical simulations
Basis functions for an MoM solution of a corner truncated patch antenna
No full textA new set of entire-domain basis functions for the numerical solution of corner-truncated patch antennas via a method of moments (MoM) algorithm is proposed in this article. The basis functions used here allow improvement of the computational efficiency and/or the accuracy of the numerical method, compared to the analysis techniques previously presented in the literature and commonly employed in practical designs. Some numerical results showing the capabilities of the new basis functions proposed here and good agreement with the measurements are also presented
Spaceborn orbito payload study and L2c antenna design for precise geosynchronous orbit/time
No full textIn this paper, the concept of a GEO navigation payload without atomic clock is
presented. The orbit/time determination is achieved by “two-way” time transfer
technique for time determination and by on board ranging measurement from GPS
satellite constellation for orbit determination.
The design of an orbito PL and dedicated GPS planar antenna is also proposed. It is a compact phased array meeting the required pattern, CoP stability, and satellite
accommodation constraints. Moreover, antenna design curves are presented
Radiating features of capacitive and inductive impedance surfaces
No full textThe radiating features of capacitive and inductive impedance surfaces are investigated in this paper. The analysis is particularly
devoted to integrated structures with reactive ground planes and is performed
through a full-wave Green’s function approach in the spectral
domain. Some numerical examples, obtained by exploiting such a rigorous
formulation, are also presented to illustrate the radiating behaviour
of infinitesimal horizontal printed dipoles mounted on reactively loaded
integrated structures. It is shown in detail that capacitive surfaces are
more suitable than inductive ones for integrated antenna applications,
due to both their effectiveness in enhancing the radiation intensity in
presence of very thin substrates and their capability of maintaining good
radiating performances over a wide frequency range
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