Reflective array antenna

About: Reflective array antenna is a research topic. Over the lifetime, 4366 publications have been published within this topic receiving 57884 citations.

Simple and Efficient Decoupling of Compact Arrays With Parasitic Scatterers

Abstract: Compact arrays such as multiple antennas on a mobile terminal suffer from low efficiency and high correlation between antenna signals. In the present paper, a simple and rigorous procedure for decoupling two closely coupled antennas with a parasitic scatterer is proposed. The parasitic scatterer, which can be an additional antenna, acts as a shield between two active antenna elements. In contrast to previous studies involving the use of parasitic scatterer for decoupling antennas, we demonstrate using antenna impedances the underlying decoupling mechanism for two arbitrary antennas. By a proper choice of parameters, perfect matching and decoupling can be obtained for a given antenna spacing without extending the overall area used, and without introducing additional decoupling networks. The price to pay is a reduction of bandwidth relative to that of widely spaced antennas, which is the case for other decoupling methods as well. Simulation and experimental results are used to substantiate the effectiveness of the proposed design approach on a two-monopole array with an antenna spacing of 0.1 wavelength. Finally, several practical considerations of the proposal are also presented, including the extension of the approach for more than two active antennas and its implementation in mobile terminals.

Near-field probe used as a diagnostic tool to locate defective elements in an array antenna

Abstract: Results of an experimental study are presented in which the near-field probe was used as a diagnostic tool to locate the defective elements in a planar array. The near-field data were processed not only to obtain the far-field patterns of the array under the test, but also to reconstruct the aperture field for diagnostic purposes. The backward transform enables the near-field probe to identify accurately aperture faults at a distance, free of interactions and couplings with the array elements. In practice, to recover the aperture field properly from the near-field distribution, the evanescent components in the computed far-field spectrum must be excluded from the inverse process with fast-Fourier-transform (FFT) techniques. For low-gain array antennas, a correction on the far-field spectrum is required to remove the contribution of the probe and the element factor before the inverse transform, strongly enhancing the resolution. >

Simulation of a phased-array antenna in waveguide

Abstract: A method has been developed for simulating a large planar phased-array antenna in order to determine the performance of its radiating elements. By simple measurements of a few elements inside of waveguides, their performance in the antenna array as a function of frequency, scan angle, and polarization may be determined. The number of elements that need to be constructed is small, and the method is well-suited to economical, empirical design of an element for an array having a very large number of elements. For this purpose, such an array is well represented by the infinite array which results from imaging by the waveguide walls. Five waveguide simulators, sampling five significant combinations of scan angle and polarization, have been developed for a particular array comprising circular elements in a square arrangement. The array impedance has been measured in the simulators, and from these measurements the reflection loss of the array has been calculated. An equivalent circuit for the element in the array has been obtained from two simple waveguide-impedance measurements, and the active impedance of the elements has been determined therefrom. Finally, these results have been employed to determine the behavior of the elements when the array is excited for circular polarization; the departure from circularity of the radiated polarization, as well as the reflection in both senses of circular polarization, have been obtained.

A shared-aperture dual-band dual-polarized microstrip array

Abstract: This paper describes the design and testing of a prototype dual-band dual-polarized planar array operating at L- and X-bands. The primary objectives were to develop new antenna technology with dual-band and dual-polarization capability in a shared aperture, featuring low mass, high efficiency, and limited beam scanning. The design of a prototype planar microstrip array of 2/spl times/2 L-band elements interleaved with an array of 12/spl times/16 X-band elements that meets these requirements is discussed in detail and measured results are presented. The array is modular in form and can easily be scaled to larger aperture sizes.

Blind estimation of multiple co-channel digital signals using an antenna array

Abstract: Proposes a novel approach for separating and estimating multiple co-channel digital signals using an antenna array. The spatial response of the array is unknown. The authors exploit the temporal structure of the digital signals to simultaneously determine the array response and the bit sequence for each signal. Uniqueness of the estimates is established for signals with BPSK modulation format. This new approach is applicable to an unknown array geometry and propagation environment, which is particularly useful in digital mobile communications. Simulation results demonstrate its promising performance. >