Active antenna

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

Design and Evaluation of an Active Antenna for a 29–47 MHz Radio Telescope Array

Abstract: The eight-meter-wavelength transient array (ETA) is a new radio telescope consisting of 12 dual-polarized, 38 MHz-resonant dipole elements which are individually instrumented, digitized, and analyzed in an attempt to detect rare and as-yet undetected single dispersed pulses believed to be associated with certain types of astronomical explosions. This paper presents the design and demonstrated performance of ETA's dipole antennas. An inverted V-shaped design combined with a simple and inexpensive active balun yields sensitivity which is limited only by the external noise generated by the ubiquitous Galactic synchrotron emission over a range greater than the 27-49 MHz design range. The results confirm findings from a recent theoretical analysis, and the techniques described here may have applications in other problems requiring in situ evaluation of large low-frequency antennas

Nonlinear antenna technology

Abstract: Nonlinear antennas combine advances in nonlinear dynamics, active antenna design, and analog microelectronics to generate beam steering and beam forming across an array of nonlinear oscillators. Nonlinear antennas exploit two phenomena typically shunned in traditional designs: nonlinear unit cells and interelement coupling. The design stems from nonlinear coupled differential equation analysis that by virtue of the dynamic control is far less complex than the linear counterparts by eliminating the need for phase shifters and beam forming computers. These advantages arise from incorporating nonlinear dynamics rather than limiting the system to linear quasisteady state operation. A theoretical framework describing beam shaping and beam forming by exploiting the phase, amplitude, and coupling dynamics of nonlinear oscillator arrays is presented. Experimental demonstration of nonlinear beam steering is realized using analog microelectronics.

Electronically steerable Yagi-Uda microstrip patch antenna array

Abstract: Summary form only given. The article describes a four microstrip Yagi-Uda antenna array. The array consists of four Yagi-Uda antennas arranged around a common reflector patch. This array is electronically steerable, having one antenna active at a time while the remaining three elements are earthed with pin diodes at their feed points. During tests the switching was done by manually swapping the feed and shorting stubs. The linear polarised radiation pattern from the array (single active antenna) at an elevation of 26 degrees above the planar array is presented.

Use of SSK Modulation in Two-Way Amplify-and-Forward Relaying

Abstract: Space-shift keying (SSK) modulation is a novel multiple-input-multiple-output (MIMO) technique, which activates only a single antenna for transmission at any time instant and uses the index of this active antenna to implicitly convey information. In this paper, a pragmatic communication strategy for the use of SSK modulation in two-way amplify-and-forward (AF) relaying is proposed. Specifically, the transceiver sends the signal by employing SSK modulation and detects the signal based on the maximal-ratio combining principle. By considering a Nakagami- m fading environment, upper bounded and asymptotic bit error probabilities (BEPs) are both derived in closed form. The optimal power allocation problem in the minimization of the average BEP is also addressed. Finally, Monte Carlo simulations are conducted to verify the accuracy of the analysis.

Integrated active antenna for multi-carrier applications

Abstract: A distributed antenna array comprising a plurality of antenna elements, and a plurality of power amplifiers, each power amplifier being operatively coupled with one of said antenna elements and mounted closely adjacent to the associated antenna element, such that no appreciable power loss occurs between the power amplifier and the associated antenna element, each said power amplifier comprising a relatively low power, linear power amplifier.