Antonio G. Pino

ICARA: induced-current analysis of reflector antennas

The aim of this work is to present the ICARA (induced-current analysis of reflector antennas) software, which is able to predict the behavior of reflector antennas using the physical optics method. The software offers different options for antenna configurations, single and array feed models, and far-field or aperture-field analysis.

Reconstructing Distortions on Reflector Antennas With the Iterative-Field-Matrix Method Using Near-Field Observation Data

This work extends the mathematical formulation of the iterative-field-matrix method for observed data from the near-field region of a Perfect Electric Conductor. The method is used as a diagnosis tool for reflector antennas, to determine the positions and extent of distortions from their idealized shapes. The new formulation is tested on a reflector antenna with several significant bumps, and excellent results are achieved. This work also presents an example where the Method of Moments is used to generate the synthetic data and the inversion is performed using Physical Optics. Such a configuration ensures that the forward model is unbiased with respect to the inversion model, demonstrating that the new formulation is also robust for these realistic scenarios.

Generating Contoured Beams With Single-Shaped Reflectors Using a Iterative Field-Matrix Approach

In this letter, a new method is presented to synthesize contoured beams by specifically shaping a single reflector antenna. The algorithm is based on the iterative-field-matrix (IFM) method, which finds a linear relationship, in a matrix form, between a local surface distortion and the difference of the nominal and objective far-field patterns. The matrix is inverted using singular value decomposition (SVD) and Tikhonov regularization; as a result, fast convergence is achieved. The method has been successfully applied to synthesize contoured beams for two different scenarios.

A compressed sensing approach for detection of explosive threats at standoff distances using a Passive Array of Scatters

This work presents a new radar system concept, working at millimeter wave frequencies, capable of detecting explosive related threats at standoff distances. The system consists of a two dimensional aperture of randomly distributed transmitting/receiving antenna elements, and a Passive Array of Scatters (PAS) positioned in the vicinity of the target. In addition, a novel norm one minimization imaging algorithm has been implemented that is capable of producing super-resolution images. This paper also includes a numerical example in which 7.5 mm resolution is achieved at the standoff range of 40 m for a working frequency of 60 GHz.

Human operator effect on wide-band radio channel characteristics

We analyze how the presence of the human operator body in the vicinity of the antenna of a portable handset modifies wide-band radio channel characteristics such as the time dispersion of the channel.

Design and Analysis of an Adjustable Subreflector for the Hybrid Mechanical-Electronic Pointing System at the Satellite Q/V Band

This paper presents some advanced results of the study developed under ESA contract for the hybrid mechanical-electronic pointing system, considered for future missions using the Q/V band. An adjustable subreflector prototype has been designed and manufactured in order to provide a scanning field of view of 4deg around a central direction. The details of the subreflector design and some simulated results of the antenna performance are presented here

A New Physical Optics Based Approach to Subreflector Shaping for Reflector Antenna Distortion Compensation

Thermal and gravitational effects distort the surface of large reflector antennas and degrade the antenna pattern. When operating with electrically large reflector antennas the surface error limits the high frequency applicability. The behavior of the distorted reflector can be improved by using various techniques to compensate the reflector distortions. This communication presents a new physical optics based approach to synthesize shaped subreflectors to achieve such a compensation. The main contribution of the communication is that the method is not based in computationally intensive calculation nor optimization and thus presents very low calculation times when applied to large antennas. Representative results and comparison with previous approaches to the same problem are presented.

Design and nearfield-based optimization on an array of reflectors as radar antenna to sense surface shape anomalies

The design and optimization of a radar array antenna aimed to detect explosives worn under clothing has been presented. Results show that the number of elements in the array and their positions can be optimized in order to minimize the SLL. The designed array accomplishes the requirements of BW and SLL necessary to illuminate the human chest with tight spots at fifty meters and allowing processing of their electromagnetic signatures separately from other illuminated areas.

Design and analysis of slot array antennas on a radial feed line

Antennas based on narrow slots directly coupled to a radial line have been used previously in direct broadcast satellite (DBS) receivers and reported by Ando (1985, 1990). One of the most important features for such antennas is their low cost and low loss feeding line, making it ideal for DBS (11.7 to 12.5 GHz operation). Most of the designs reported are based on experimental work or at least no systematic design procedure have been shown. This paper shows an easy design procedure based on the analysis of several narrow slots coupled to the line. A final, more accurate analysis can be done for the complete antenna including the coupling effect between slots.

Cosecant-squared power pattern synthesis procedure for an hour-glass reflector antenna with sectorial beams

The aim of this communication is to present the synthesis procedure of an hour-glass antenna in order to obtain sector beams with cosecant-squared far-field power elevation pattern. This antenna is able to produce a number of sectorial and reconfigurable beams which satisfy the radiation pattern envelope (RPE) in the ETSI standard.