Active antenna

About: Active antenna is a research topic. Over the lifetime, 2246 publications have been published within this topic receiving 26493 citations.

Frequency multiplication and QPSK modulation with subharmonic injection-locked active antenna

Abstract: A subharmonic injection-locked oscillating antenna, operating simultaneously as a frequency doubler and as a QPSK modulator, is presented. A dual-gate MESFET is used with one of its gates integrated with a PIN diode switch controlled patch antenna and the other gate connected to a low-noise subharmonic stabilising signal. The experimental and simulation results demonstrate the possibility of the simultaneous realization of frequency multiplication by subharmonic injection locking and phase modulation through DC bias and PIN diode switch.

Active antenna systems for centralized self-optimization of capacity in LTE-A

Abstract: Network Quality-of-Service (QoS) improvements in terms of capacity can be brought about by optimizing antenna tilts. Active Antenna Systems (AAS) are gaining wide interest recently for their agile ability to electronically adjust the beam in the optimum direction based on operators' QoS interests. In our previous work, we had proposed a novel technique for centralized self-optimization using an iterative modeling and optimization framework called as “surrogate-based optimization”. This framework involves: 1-the use of a stochastic model which can be used “as a surrogate” (i.e. to replace) the functional relationships between the network parameters and Key Performance Indicators (KPI), and 2-a subsequent use of a pattern search algorithm as an optimization process, in an iterative manner. In this work, we propose to use the surrogate-based framework for optimization of antenna tilts in Long Term Evolution Advanced (LTE-A) networks and compare optimization results of several capacity based objectives. Results using a flow level network simulator reveals the need to jointly optimize multi-capacity-objectives in a centralized manner apart from demonstrating the superiority of the iterative self-optimization methodology in terms of fast convergence, adaptivity and flexibility.

Broadband active multi-beam antenna system and correction method thereof

Abstract: The invention relates to the field of broadband array antennas, in particular to a broadband active multi-beam antenna system, which comprises a broadband active antenna array and a multi-beam network, wherein the broadband active antenna array comprises at least two column line sources and multifunctional radio-frequency front ends and a control unit; the column line sources receive multiple paths of radio-frequency signals and carry out pitching direction synthesis; the multifunctional radio-frequency front ends carry out low-noise amplifying, filtering, amplitude weighting and phase shift processing on the radio-frequency signals output by the column line sources; the control unit receives a control instruction input from the outside and adjusts attenuation and phase shift code values in the multifunctional radio-frequency front ends; and the multi-beam network synthesizes the radio-frequency signals output by the multifunctional radio-frequency front ends on the basis of lens network implementation and simultaneously outputs multiple paths of beams in an azimuth direction. A near field diameter inversion correction method is adopted by the broadband active multi-beam antenna system. Compared with a broadband multi-beam system formed by digital beams, the broadband active multi-beam antenna system has the advantages that the equipment quantity is greatly reduced, the weight, the cost and the power consumption are greatly reduced and the broadband active multi-beam antenna system is easily applied to engineering.

Space-time diversity for active antenna systems

Abstract: In this chapter, different techniques for improving radar performance in detection, location and classification of targets, through simultaneous transmission of radar signals in different directions, are analysed and discussed. After a brief introduction to the benefits and limitations of wide instantaneous angular coverage, the principles of space-time coding - i.e. sending simultaneously different signals through the different subarrays of a phased-array antenna - are described and illustrated by a few examples, e.g. intra-pulse scanning, circulating pulse or interleaved scanning. Generic techniques for codes optimization are then examined and shown to open the way to space-time adaptivity. A quantitative analysis of diversity gain demonstrates the benefits of high resolution inherent to wideband space-time radar systems, and a tentative classification of space-time codings is proposed. The conclusion emphasizes the benefits to be obtained from those space-time techniques, which will become accessible in near future, taking advantage of the current evolution towards agile front-ends and smart mode management systems for future radars.

Surface-wave coupling of active antennas for homodyne sensor systems

Abstract: In this paper, we present a novel method for significantly enhancing the performance of low-cost millimeter-wave sensor systems based on active integrated antennas. Our method uses the planar active antenna's parasitic surface-wave field as a local oscillator signal for a mixing rectenna. Compared to a self-mixing active 67-GHz antenna, the surface-wave coupled rectenna receiver shows a considerably improved minimum detectable signal (10 dB lower) and the possibility for high-quality homodyne in-phase/quadrature signal detection.