Active antenna

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

Mode change analysis of a two element oscillator-type antenna array

Abstract: An array of two radiation coupled oscillator-type antennas is investigated to confirm the behaviour of the antenna system as a function of the strength of mutual coupling between elements. Array behaviour prediction requires correct array mode identification; thus, a simple method whereby the stability of these modes can be identified is presented. An analysis is performed which assumes radiation coupling between identical active antenna oscillators. Explicit equations are given for the locked frequency and individual amplitudes of the array elements for each mode of operation. Theoretical predictions are compared with experimental results to confirm amplitude, frequency and phase variation features in the vicinity of the element separation where mode change occurs. The results compare well with those observed in practice where a mode change is observed as the element separation is increased by half wavelength intervals. In addition, the available modes in a two element array, the in-phase and antiphase conditions, are examined at full-wavelength and half-wavelength separations. The in-phase mode is seen to be stable for full-wavelength separations while the antiphase mode is stable at half-wavelength separations.

Phased-array behavior of a one-dimensional mutually coupled oscillator system controlled by injection signals

Abstract: The system configuration, fundamental operation, and PSK modulation of the output wave are discussed for the phased array operation of a mutually coupled one-dimensional oscillator array when signals with different phases are injected at the two ends to make use of the mutual locking and injection locking phenomena. First, the equivalent circuit is analyzed and the condition of phased array operation is derived. It is shown that both the desired mode, appropriate for the phased array operation, and other modes exist. It is demonstrated that injecting the injection signal at the center of the array is effective in enhancing the stability of the desired mode. The transient response of the array is analyzed when a PSK signal is used as the injection signal. A possible means of obtaining a PSK modulated wave as the output is presented. An experiment in the X band, using waveguide oscillators and an active patch antenna array is described. The results are close to the theoretical predictions. © 1997 Scripta Technica, Inc. Electron Comm Jpn Pt 2, 80(2): 45–56, 1997

High-reliable GPS digital optical fiber repeater applied to railway

Abstract: The invention provides a high-reliable GPS digital optical fiber repeater applied to a railway. The high-reliable GPS digital optical fiber repeater applied to the railway comprises a master hub unitand a plurality of remote optic units which are connected by optical fibers, wherein the master hub unit is connected with a GPS satellite through a GPS antenna, and the remote optic units are connected with retransmission antennas; the master hub unit comprises a main line and a spare line, and each line comprises a master hub unit filter, a low noise amplifier LNA and a master hub unit digital intermediate frequency module with frequency conversion, which are connected successively; and each remote optic unit comprises main and spare remote optic unit digital intermediate frequency modules with frequency conversion and main and spare power amplifiers, which are connected by a combiner, wherein the main and spare power amplifiers are connected with the retransmission antenna through a radio frequency switch and a remote optic unit filter successively. The invention adopts a customized GPS active antenna to solve the problem of the GPS signal coverage indoors and in a tunnel, and supports a variety of networking modes, such as star, chain, ring and mixed networking, so as to provide DC5V to 12V/200m feed radio frequency interfaces for the customized GPS active antenna.

Use of RF MEMS and micromachined parts to realize highly integrated V band active feed for satellite antennas

Abstract: Micromachining and microelectromechanical systems (MEMS) technologies can play a key role in miniaturization of satellite antenna front-ends. Alcatel Alenia Space France has demonstrated for the first time the operation of a V band integrated active feed combining 3D stacking concepts and micromachining technologies. The realized integrated module size is 35 times 35 mm2 with a thickness of 7 mm including miniaturized DC and RF connectors. In this paper, we present the latest test results obtained on this MEMS based active antenna